Fish farming systems

Abstract

The disclosure relates to a fish farming system (100), comprising a floatable structure (101) comprising a collar (102) and an access structure (108). A fish enclosure (104) is suspended from the floa

Description

[0001] FISH FARMING SYSTEMS

[0002] FIELD

[0003] Some examples relate to a fish farming system and a method of operation thereof. Other examples relate to a utility structure for a fish farm and a method for providing a utility to a fish farm.

[0004] BACKGROUND

[0005] The problem of overfishing and the consequences thereof have been known for many years. One solution to meet consumer demand for fish, while at the same time preserving natural fish stocks, is to operate fish farms. Such fish farms may be able to rear large quantities of fish in captivity, thereby reducing strain on natural fish stocks.

[0006] As technology relating to fish farms has developed, there has been a continual focus on safety, fish welfare and the environmental impacts of fish farming, which in turn has driven a demand for improved method and solutions for fish farming. Most often, fish farms are located near shore in coastal areas in the sea or ocean, where the fish farm can have some protection resulting from the natural landscape of fjords or archipelagos, or even in large lakes or rivers or in basins on land. In order to reduce the impact of environmental forces on a fish farm, it may be desirable or necessary to locate a fish farm in a sheltered location, where waves are likely to be smaller than in the open sea or ocean. However, in doing so, different problems may arise, for example the available space in a natural bay may be limited, and the through-flow of water may be restricted, which may place an upper limit on the possible biomass in the area with respect to oxygen and emissions. The proximity to other fish farms may also provide an increased risk of spreading diseases between fish. Therefore having the ability to position a fish farm in an open-water, or more exposed, location would permit a user to avoid these drawbacks.

[0007] However, the simple placement of a currently used fish farm in an offshore location is not possible in the long term, as these fish farms are often designed with some form of natural protection in mind. As such, if placed offshore, the environmental forces (e.g. from wind and waves) surrounding the fish farm would be greater than expected and would result in damage both from the wind, and from waves, which forces increase with proximity to the sea or ocean surface. Most importantly, the working environment and fish welfare would likely not be acceptable if a conventional fish farm is located in an offshore location

[0008] While positioning a fish farm in an open-water location provides more space, problems such as parasites (e.g. sea lice), and some diseases, still persist. This is particularly the case near the water surface, or in the upper part of the water column. Further, where the fish farm is located in a colder climate, ice can form on the net and other structural components of the fish farm that are positioned above the water. Floating ice may produce large loads on the net structure and the collar at the surface. In response to these challenges, some attempts have been made to provide submersible fish farms that move both the fish and the structure, including the net, away from the parasites, diseases, ice and environmental loads found at or towards the surface. However, such attempts have been met with different problems, such as a lack of vertical stability of submerged structures, a lack of an air supply for swim bladder adjustment of physostomous fish, and straightforward and robust access to the fish enclosure for maintenance, replacement and monitoring of equipment and systems, while simultaneously permitting long-term submergence.

[0009] There is therefore a need for a fish farm that is able to solve the above problems, for example of parasites, disease and large wave impact forces, without suffering from the problems experienced by known submersible fish farms.

[0010] The above problems can alternatively be addressed, at least in part, by the use of a closed fish farming system, and this can facilitate fish farming in suboptimal locations and closer to other fish farms.

[0011] Conventional closed systems may be used in some cases where it is desired to have some form of isolation between the fish farm and the surrounding environment, and may also permit the collection of feed spill and other waste that is generated in a fish enclosure. Conventional closed systems may involve, for example, an enclosure formed from a flexible bag, or an enclosure formed with a rigid basin. However, conventional closed systems can be very sensitive to adverse weather conditions. Such fish enclosures may be more prone to deformation in a body of water, owing to the fact that the closed material is more affected by wave and tidal forces in a body of water, and to changes in pressure therein. Conventional closed fish enclosures can also suffer from the phenomenon of internal wave systems forming inside the fish enclosure which may be exacerbated by external wave forces, and may also exhibit less predictable hydrodynamic behaviour. All of these issues can cause damage to both the fish farm structure and to the fish therein.

[0012] Moreover, holding large quantities of fish in a fish farm places a large amount of responsibility on the owner or manager of the fish farm, as the fish farm may require a large degree of monitoring and maintenance. For example, frequent feeding and monitoring of the health of the fish is required, as well as frequent cleaning and maintaining of the fish farm itself. One way to provide feed, as well as maintenance and cleaning utilities, to a fish farm is to moor a barge or service vessel (such as a feed barge) near to the location of the fish farm, and provide the fish farm with utilities as needed. Utilities such as feed and electricity are typically provided through hoses and cables from the feed barge.

[0013] A drawback associated with conventional feed barges is that they may be required to be moored for an extended period of time, and during this period may be vulnerable to harsh weather conditions. The feed barges are typically spread moored (or part of a frame mooring with other fish farm structures) with mooring lines connected to the corners of the feed barge to provide yaw stiffness and limit rotation around the vertical axis, as such rotation can damage cables and hoses connecting the barge and the cages of the fish farm. Harsh weather conditions, especially from unfavorable directions, may exert an environmental load on the vessel, which can result in damage to the vessel, a reduced lifespan, or both. Further, in exposed offshore locations, the frequency of waves impacting on the vessel may be similar to the natural frequency of the roll of the vessel, which may result in large vessel roll, and a potentially dangerous situation for personnel onboard. In sheltered locations, mooring a vessel for a long period of time may be a viable solution. However, in more exposed locations (e.g. in offshore locations) and locations with large sector for environmental direction, mooring of a barge may prove more problematic. In addition, connecting and disconnecting conventional feed barges for supplying a fish farm to and from the mooring system can be time consuming and requires specialised equipment and calm weather conditions. Therefore, connection and disconnection of conventional feed barges from known mooring systems is not a viable option for mitigating against the effects of severe weather conditions.

[0014] There is therefore a need for a barge or service vessel for a fish farm that is able to be moored in exposed locations without being at a risk of sustaining excessive damage, and / or posing a risk to personnel onboard.

[0015] For a better understanding of the background, patent NO345546 discloses a fish farm and associated systems and methods, and in particular methods for conveyance and communication between different units within a fish farm.

[0016] SUMMARY

[0017] It is an object of the present disclosure to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages in the prior art and solve at least the above mentioned problem. According to a first aspect there is provided a fish farming system, comprising a floatable structure comprising a collar and an access structure which is floating on a body of water, the collar defining an access opening therein for providing access to the fish enclosure, and the collar being submerged in the body of water, and the access structure connected to the collar, and extending from a submerged location at which the access structure connects to the collar, to a location above a waterline of the body of water, the system further including a fish enclosure containing fish which is suspended from the floatable structure via a suspension arrangement so that an uppermost portion of the fish enclosure is spaced from a lowermost edge of the floatable structure.

[0018] The system may comprise a hang-off support which is mounted on the floatable structure, the suspension arrangement comprising an elongate element and a stop, the elongate element extending from the fish enclosure to the stop, the stop engaging with the hang-off support so that the fish enclosure is supported by the hang-off support via the stop and the elongate element, so that the uppermost portion of the fish enclosure is spaced from the lowermost edge of the floatable structure.

[0019] According to some examples, the fish farming system may comprise a height adjustment means located on at least one of the access structure and the suspension arrangement, the height adjustment apparatus being operable to raise and lower the fish enclosure relative to the floatable structure. The fish enclosure may comprise at least one of an upper structure and a lower structure. The fish enclosure may comprise both an upper structure and a lower structure.

[0020] The fish enclosure comprises a weighted frame and an air pocket. The air pocket may be housed in the upper structure and the weighted frame is defined by the lower structure.

[0021] The collar may have a polygonal vertical cross-section. The collar may have a rectangular vertical cross-section. The collar may comprise a collar extension in the form of a heave plate connected thereto.

[0022] The suspension arrangement may extend from the access structure to the enclosure. The suspension arrangement may comprise a flexible elongate member that extends between the floatable structure and the fish enclosure.

[0023] The access structure may comprise a height adjustment means for raising and lowering the fish enclosure relative to the floatable structure. In some examples, the height adjustment means may comprise an elongate member extending from the access structure to the fish enclosure. The height adjustment means may comprise a connector to a winch, and in some examples may be selectively operable by a user.

[0024] The access structure may be or comprise a plurality of discreet columns extending from the collar. One discreet column may not be connected to another discreet column. The discreet columns may be evenly spaced apart on the collar. The discreet columns may be unevenly spaced on the collar. In some examples, the discreet columns may be arranged in groups of columns that comprise a closer spacing between columns (e.g. the width of one or two columns) relative to the distance between other columns, and may therefore be unevenly spaced. Each of the discreet columns configurable to extend from a submerged point of contact with the collar to a location above a waterline.

[0025] The fish farming system may comprise a hang-off arrangement located at the base of the collar. The suspension arrangement may be coupled to the hang-off arrangement. The hang-off arrangement may comprise a restrictor comprising a seat for a plug located on the suspension arrangement. The plug may be configured to be seated in the restrictor, such that movement of the suspension arrangement relative to the collar is restricted.

[0026] The collar may have a polygonal horizontal cross-section (e.g. a perpendicular or lateral cross-section, relative to a central axis through the access opening in the collar, which may be substantially vertically oriented in normal operation of the system), and may comprise an access structure at each corner, point, apex, or the like thereof. The collar may has a rectangular horizontal cross-section, and comprises an access structure at each corner thereof.

[0027] The fish farming system may comprise a plurality of access structures. Each of the plurality of access structures may be located radially inwardly of the collar. Reference to the access structure in this text is intended to cover examples in which there exists both one access structure, and a plurality of access structures, unless otherwise stated.

[0028] The fish enclosure may comprise access to a source of feed. The fish farming system may comprise an access column extending between the access structure and the fish enclosure. The access column may provide access to the source of feed. The source of feed may be located on the floatable structure, on a supply vessel which may be moored adjacent the system, or the like.

[0029] The collar may comprise a lice skirt. The lice skirt may be at least partially supported by the access structure or structures, and may be configurable to extend above a waterline.

[0030] According to a second aspect there is a method for operation of a fish farming system, comprising: providing a floatable structure, comprising a collar and an access structure located on the collar, in a body of water; submerging the collar below a waterline in the body of water such that the access structure extends between a submerged point of contact with the collar and a location above the waterline of the body of water; suspending a fish enclosure containing fish from the floatable structure via a suspension arrangement so that an uppermost portion of the fish enclosure is suspended below and spaced from a lowermost edge of the floatable structure; providing access to the fish enclosure through the collar via a central recess defined in the collar.

[0031] The system may comprise a hang off support mounted on the floatable structure, and the suspension arrangement comprises an elongate element and a stop, the elongate element extending from the fish enclosure to the stop, and the method comprise suspending the fish enclosure from the floatable structure by engaging the stop with the hang-off support.

[0032] The method may comprise, prior to placing fish in the fish enclosure, connecting the fish farming system to a vessel. The method may comprise towing the fish farming system to a desired location in a body of water.

[0033] The method may comprise, prior to placing fish in the fish enclosure, installing the fish farming system in a body of water via a crane on a vessel.

[0034] The fish farming system may further comprise a height adjustment apparartus located on at least one of the access structure and the suspension arrangement, the height adjustment apparatus being operable to raise and lower the fish enclosure relative to the floatable structure, and the method may comprise carrying out a service operation by using the height adjustment apparatus temporarily to lift the fish enclosure at least partially above the waterline.

[0035] Further aspects described herein may be summarised by the following series of inventive clauses.

[0036] CLAUSE 1 . A fish farming system, comprising: a floatable structure comprising a collar and an access structure; a fish enclosure configurable to be suspended from the floatable structure via a suspension arrangement; at least one of the collar and the access structure being configurable to have positive buoyancy in a body of water.

[0037] CLAUSE 2. The fish farming system of clause 1 , wherein the access structure (e.g. only the access structure) has positive buoyancy in a body of water.

[0038] CLAUSE 3. The fish farming system of clause 1 or 2, wherein at least a part of the access structure, and optionally at least a part of the collar, is located above a waterline in a body of water.

[0039] CLAUSE 4. The fish farming system according to any preceding clause, comprising a height adjustment means comprising an elongate member connecting the fish enclosure to the access structure for varying the elevation of the fish enclosure relative to the floatable structure, and wherein the suspension arrangement comprises an elongate member connecting the fish enclosure to the floatable structure for bearing the weight of the fish enclosure.

[0040] CLAUSE 5. The fish farming system according to clause 4, wherein the height adjustment means is configurable to connect to a vessel or offshore platform, and for example may comprise a connector or connection profile therefor.

[0041] CLAUSE 6. The fish farming system according to any preceding clause, wherein the floatable structure comprises a self-ballasting arrangement or structure for varying the hydrodynamic added mass of the fish farming system or reducing ballast capacity, optionally comprising at least one tank with at least one passive opening therein.

[0042] CLAUSE 7. The fish farming system according to any preceding clause, wherein the floatable structure comprises an auxiliary support structure, for example in the form of a truss structure, optionally an elongate truss structure.

[0043] CLAUSE 8. The fish farming system according to any preceding clause, wherein the fish enclosure comprises a rigid upper structure and a rigid lower structure for supporting a boundary material (such as a net), and the rigid upper structure defines an air pocket therein.

[0044] CLAUSE 9. The fish farming system according to clause 8, wherein the fish enclosure is configurable between a raised position and a lowered position, and the floatable structure comprises a skirt extending to the depth of the lower structure when the fish enclosure is in the raised position.

[0045] CLAUSE 10. The fish farming system according to any preceding clause, comprising an air access tube extending from the fish enclosure to the floatable structure.

[0046] CLAUSE 11 . The fish farming system according to any preceding clause, wherein the floatable structure comprises a plurality of collars, for example two collars, three collars or four collars. CLAUSE 12. The fish farming system according to clause 11 , wherein adjacent collars of the plurality of collars share at least one edge.

[0047] CLAUSE 13. The fish farming system according to any preceding clause, comprising a plurality of access structures.

[0048] In this and other described examples, the collar may define an access opening therein for providing access to the fish enclosure.

[0049] Further aspects described herein may be summarised by the following series of inventive A-clauses.

[0050] CLAUSE A1 . A fish farming system, comprising: a floatable structure; a fish enclosure configurable to be suspended from the collar via a suspension arrangement; height adjustment means for raising and lowering the enclosure relative to the floatable structure; and the collar comprising a selectively deployable protector comprising a lice skirt extending around the periphery thereof, the selectively deployable protector being configurable between a retracted and a deployed configuration.

[0051] CLAUSE A2. The fish farming system of clause A1 , wherein the protector additionally comprises a secondary net.

[0052] CLAUSE A3. The fish farming system of clause A1 or A2, wherein the selectively deployable protector is an expandable protector and the deployed configuration is an expanded configuration.

[0053] CLAUSE A4. The fish farming system of any of clauses A1 to A3, wherein the protector is collapsible.

[0054] CLAUSE A5. The fish farming system of any of clauses A1 to A4, wherein the collar is circular in shape.

[0055] CLAUSE A6. The fish farming system of any of clauses A1 to A4, wherein the collar is polygonal in shape.

[0056] CLAUSE A7. The fish farming system of any of clauses A1 to A6, wherein the protector comprises a plurality of lice skirts, each extending partially around the periphery of the collar.

[0057] CLAUSE A8. The fish farming system of any of clauses A1 to A7, wherein the collar is configured to float on the surface of a body of water.

[0058] CLAUSE A9. The fish farming system of any of clauses A1 to A8, wherein the collar is configurable to be fully submerged in a body of water. CLAUSE A10. The fish farming system of any of clauses A1 to A9, wherein the collar is configurable between an operational draft, in which the collar is fully submerged in a body of water, and a maintenance draft, in which the collar floats on the surface of a body of water, for example a portion of the collar being located above the waterline.

[0059] CLAUSE A11 . The fish farming system of any of clauses A1 to A10, wherein the protector comprises an upper lice skirt and a lower lice skirt located below the upper lice skirt, the upper lice skirt being partially submerged and the lower lice skirt being fully submerged in a body of water.

[0060] CLAUSE A12. The fish farming system of clause A11 , wherein the lower skirt has a greater width or diameter than the upper skirt.

[0061] CLAUSE A13. The fish farming system of clause A11 or A12, wherein the upper skirt has a width or diameter equal to an inner width or diameter of the collar, and the lower skirt has a width or diameter equal to an outer width or diameter of the collar.

[0062] CLAUSE A14. The fish farming system of any of clauses A1 to A13, wherein the height adjustment means is configurable to move the fish enclosure between a first configuration in which the fish enclosure is in an raised position and a second configuration in which the fish enclosure is in a lowered position relative to the floatable structure, wherein in the raised position at least a portion or all of the fish enclosure is located at the same height as the protector, and in the lowered position the fish enclosure is located below (e.g. completely below) the protector.

[0063] CLAUSE A15. A method of surfacing a fish enclosure of a submersible fish farming system, comprising: suspending a fish enclosure in a first position from a floatable structure of a fish farming system in a body of water via a suspension arrangement; configuring a selectively deployable protector located on the floatable structure to a retracted configuration when the fish enclosure is in the first position; raising the fish enclosure to a second position, which is closer to the floatable structure than the first position; configuring the selectively deployable protector to a deployed configuration when the fish enclosure is in the second position.

[0064] CLAUSE A16. The method according to clause A15, wherein the first position of the fish enclosure is an operational position, and the second position is a maintenance position.

[0065] CLAUSE A17. The method according to clause A15 or A16, wherein in the second position at least a part of the fish enclosure is located at the waterline.

[0066] Further aspects described herein may be summarised by the following series of inventive B-clauses. CLAUSE B1 . A fish farming system, comprising: a floatable structure; a fish enclosure configurable to be suspended from the floatable structure via a suspension arrangement; an access tube comprising a conduit extending between the suspended fish enclosure and the floatable structure.

[0067] CLAUSE B2. The fish farming system of clause B1 , wherein the access tube is rigid.

[0068] CLAUSE B3. The fish farming system of clause B1 , wherein the access tube is flexible.

[0069] CLAUSE B4. The fish farming system of any of clauses B1 to B3, wherein the access tube is collapsible.

[0070] CLAUSE B5. The fish farming system of any of clauses B1 to B4, wherein the access tube comprises a connection point with the floatable structure and a connection point with the fish enclosure.

[0071] CLAUSE B6. The fish farming system of any of clauses B1 to B5, wherein the access tube comprises at circular cross-section.

[0072] CLAUSE B7. The fish farming system of any of clauses B1 to B6, wherein the access tube comprises a square or rectangular cross-section.

[0073] CLAUSE B8. The fish farming system of any of clauses B1 to B7, wherein the access tube is for housing cabling extending between the collar and the fish enclosure.

[0074] CLAUSE B9. The fish farming system of any of clauses B1 to B8, wherein the access tube comprises cabling extending between the collar and the fish enclosure.

[0075] CLAUSE B10. The fish farming system of any of clauses B1 to B9, wherein the access tube is for passing an ROV therethrough.

[0076] CLAUSE B11 . The fish farming system of any preceding B clause, wherein the access tube is made from a water impermeable material.

[0077] CLAUSE B12. The fish farming system of any preceding B clause, wherein the fish enclosure is located entirely below the floatable structure.

[0078] Further aspects described herein may be summarised by the following series of inventive C-clauses.

[0079] CLAUSE C1 . A fish farming structure for a closed fish farm, comprising: a floatable structure comprising a collar and an access structure; a closed fish enclosure configurable to be suspended from the floatable structure via a suspension arrangement; the collar defining an access opening therein for providing access to the fish enclosure, and the collar being configurable to be submerged in a body of water; the access structure located on the collar, and being configurable to extend from a submerged location at which the access structure connects to the collar to a location above a waterline of a body of water; and the closed fish enclosure being configurable to extend above the level of the collar.

[0080] CLAUSE C2. The fish farming structure according to any preceding clause, wherein the fish enclosure comprises a water impermeable barrier.

[0081] CLAUSE C3. The fish farming structure according to clause C1 or C2, wherein the closed fish enclosure comprises a fluid outlet for permitting flow of a fluid from the fish enclosure to a body of water, and a fluid inlet for permitting flow of a fluid to the fish enclosure from a body of water, wherein the fluid flow rate through the fluid inlet is selectably variable so as to permit raising and lowering of the water level of a water volume inside the closed fish enclosure.

[0082] CLAUSE C4. The fish farming structure according to clause C3, wherein the water level of the water volume inside the closed fish enclosure is configurable to be higher than the waterline of a surrounding body of water.

[0083] CLAUSE C5. The fish farming structure according to clause C3 or C4, wherein the water inlet comprises a fluid pump.

[0084] CLAUSE C6. The fish farming structure according to any of clauses C3 to C5, wherein the water inlet comprises an inlet conduit extending from below the fish enclosure at least to the level of the fish enclosure.

[0085] CLAUSE C7. The fish farming structure according to clause C6, wherein the inlet conduit extends through the access structure.

[0086] CLAUSE C8. The fish farming structure according to any preceding C clause comprising a waste removal arrangement located inside the access structure.

[0087] CLAUSE C9. The fish farming structure according to any preceding C clause wherein the collar forms a closed loop which surrounds the closed fish enclosure and the access structure comprises a plurality of access elements which extend upwardly from the collar at the submerged located to the location above the waterline of the body of water.

[0088] CLAUSE C10. The fish farming structure according to any preceding C clause, wherein the collar is circular in shape. CLAUSE C11 . The fish farming structure according to any preceding C clause, wherein the collar is polygonal in shape.

[0089] CLAUSE C12. The fish farming structure according to clause C9, wherein the access structure comprises a support structure which extends between at least two of the plurality of access elements.

[0090] CLAUSE C13. The fish farming structure according to clause C12, wherein the fish enclosure is connected to the support structure.

[0091] CLAUSE C14. The fish farming structure according to any preceding C clause, wherein the closed fish enclosure is connected directly to the access structure.

[0092] CLAUSE C15. The fish farming structure according to any preceding C clause, wherein the closed fish enclosure is connected directly to each of the plurality of access elements.

[0093] CLAUSE C16. The fish farming structure according to any preceding C clause, wherein the suspension arrangement comprises a first and a second elongate member that connect the floatable structure to the fish enclosure via a first and a second pulley, the first and second pulleys being located on the access structure.

[0094] CLAUSE C17. The fish farming structure according to any preceding C clause, comprising a roof enclosure.

[0095] CLAUSE C18. The fish farming structure according to any preceding C clause, wherein the roof enclosure is inflatable.

[0096] CLAUSE C19. The fish farming structure according to any preceding C clause, wherein the access structure comprises a horizontal protrusion, the suspension arrangement extending from an underside of the protrusion.

[0097] CLAUSE C20. The fish farming structure according to any preceding C clause, wherein the fish enclosure is comprised of at least one section of water impermeable material, and at least one section of water permeable material.

[0098] CLAUSE C21 . The fish farming structure according to clause C20, wherein the at least one section of water permeable material is located at an upper section of the fish enclosure and locatable above the water level in the fish enclosure, and the at least one section of water impermeable material is located at a lower section of the fish enclosure.

[0099] CLAUSE C22. The fish farming structure according to any preceding C clause, comprising a mort collection arrangement comprising a conduit extending from the fish enclosure to a mort container.

[0100] CLAUSE C23. A method of operating a closed fish farm comprising a floatable structure which includes a collar and an access structure and a closed fish enclosure, wherein the method comprises locating the floatable structure in a body of water so that the collar is submerged in the body of water and the access structure extends from the collar at a submerged location at which the access structure connects to the collar to a location above the waterline of the body of water, suspending the closed fish enclosure from the access structure via a suspension arrangement so that the collar surrounds the closed fish enclosure and a top portion of the closed fish enclosure is always located above the waterline of the body of water.

[0101] CLAUSE C24. A method of operating a closed fish farm according to claim C23 further comprising maintaining the fish enclosure at a generally constant level in the body of water.

[0102] CLAUSE C25. A method of operating a closed fish farm according to clause C23 or C24, the fish farm having any of the features of the fish farming structure set out in clauses C1 - C22 above.

[0103] Further aspects described herein may be summarised by the following series of inventive D-clauses.

[0104] CLAUSE D1 . A fish farming structure for a closed fish farm, comprising: a floatable structure comprising a collar; a closed fish enclosure configurable to be suspended from the floatable structure via a suspension arrangement; the collar defining an access opening therein for providing access to the fish enclosure; the closed fish enclosure comprising an upper and a lower portion, the upper portion extending between the floatable structure and a connection to a structural frame, and the lower portion extending from the connection to the structural frame to form a base of the closed fish enclosure.

[0105] CLAUSE D2. A fish farming structure according to clause D1 , wherein the collar is configurable to be submerged (e.g. completely submerged) and the floatable structure comprises an access structure, the access structure located on the collar, and being configurable to extend from a submerged location at which the access structure connects to the collar to a location above a waterline of a body of water.

[0106] CLAUSE D3. A fish farming structure according to clause D1 or D2, wherein the closed fish enclosure comprises a fluid outlet for permitting flow of a fluid from the fish enclosure to a body of water, and a fluid inlet for permitting flow of a fluid to the fish enclosure from a body of water, wherein the fluid flow rate through the fluid outlet is selectably variable so as to permit raising and lowering of the water level of a water volume inside the closed fish enclosure.

[0107] CLAUSE D4. A fish farming structure according to clause D3, wherein the fluid inlet comprises an inlet conduit having an inlet positionable below the fish enclosure, and the inlet conduit having an outlet located in the fish enclosure and below the water level of a water volume inside the closed fish enclosure.

[0108] CLAUSE D5. A fish farming structure according to clause D3 or D4, wherein the inlet conduit is connected (e.g. directly connected) to the structural frame. CLUASE D6. A fish farming structure according to clause D5, wherein the inlet conduit is connected to the frame via a sleeve that is connected to the frame, for example via a tie, a rigid or flexible connector, or the like.

[0109] CLAUSE D7. A fish farming structure according to clause D5, wherein the inlet conduit extends through the frame.

[0110] CLAUSE D8. A fish farming structure according to any of clauses D3 to D7, wherein floatable structure comprises an access structure, and the inlet conduit extends through the access structure.

[0111] CLAUSE D9. A fish farming structure according to any of clauses D3 to D8, wherein the fluid outlet comprises a fluid pump.

[0112] CLAUSE D10. A fish farming structure according to any of clauses D3 to D9, where the fluid outlet comprises one or a plurality of fluid ports located in the closed fish enclosure.

[0113] CLAUSE D11 . A fish farming structure according to clause D10, wherein the fluid outlet comprises a fluid port in the upper portion and a fluid port in the lower portion.

[0114] CLAUSE D12. A fish farming structure according to any preceding D clause, wherein the closed fish enclosure comprises a waste outlet, the waste outlet optionally comprising a conduit extending from the waste outlet to a waste containment unit (e.g. a mort container or separation chamber) in or on the floatable structure.

[0115] CLAUSE D13. A fish farming structure according to any preceding D clause, wherein the collar and the frame have a circular annulus shape.

[0116] CLAUSE D14. A fish farming structure according to any of clauses D1 to D12, wherein the collar and the frame have a polygonal annulus shape, or a polygonal cross section.

[0117] CLAUSE D15. A fish farming structure according to any preceding D clause, wherein the closed fish enclosure comprises at least one flow obstructer extending into the fish enclosure, and the at least one flow obstructer is in the form of a fin.

[0118] CLAUSE D16. A fish farming structure according to any preceding D clause, wherein the closed fish enclosure comprises a plurality of sub-enclosures therein.

[0119] CLAUSE D17. A fish farming structure according to any preceding D clause, wherein the structural frame is rigid.

[0120] Various further inventive aspects and embodiments according to the present disclosure will now be outlined in the following E-clauses:

[0121] CLAUSE E1 . A fish farming structure for a closed fish farm, comprising: a floatable structure comprising a collar (and optionally an access structure); a closed fish enclosure configurable to be suspended from the floatable structure via a suspension arrangement; the closed fish enclosure comprising a first enclosure and a second enclosure, an enclosed intermediate water volume being contained between the first enclosure and the second enclosure and at least one of the first enclosure and the second enclosure being a closed enclosure. CLAUSE E2. The fish farming structure according to clause E1 , wherein both the first enclosure and the second enclosure are closed enclosures.

[0122] CLAUSE E2. The fish farming structure according to clause E1 , wherein the first enclosure is completely contained within the second enclosure.

[0123] CLAUSE E3. The fish farming structure according to clause E1 , wherein the first enclosure is partially contained within the second enclosure, optionally wherein only an upper portion of the first enclosure is contained within the second enclosure, and a lower portion of the first enclosure is located outside of the second enclosure.

[0124] CLAUSE E4. The fish farming structure according to any preceding E clause, wherein one of the first and second enclosures is water permeable, and one of the first and second enclosures is water impermeable.

[0125] CLAUSE E5. The fish farming structure according to any of clauses E1 to E3, wherein both of the first and second enclosures are water permeable.

[0126] CLAUSE E6. The fish farming structure according to any preceding E clause, wherein the fish enclosure comprises at least a third closed fish enclosure.

[0127] CLAUSE E7. The fish farming structure according to clause E6, wherein both the first fish enclosure and the second fish enclosure are contained within the at least third fish enclosure.

[0128] CLAUSE E8. The fish farming structure according to any preceding E clause, wherein the first fish enclosure comprises an upper and a lower portion, the upper portion extending between the floatable structure and a connection to a structural frame, and the lower portion extending from the connection to the structural frame to form a base of the closed fish enclosure.

[0129] CLAUSE E9. The fish farming structure according to any preceding E clause, wherein the second closed fish enclosure comprises an upper and a lower portion, the upper portion extending between the floatable structure and a connection to a structural frame, and the lower portion extending from the connection to the structural frame to form a base of the closed fish enclosure.

[0130] CLAUSE E10. The fish farming structure according to any preceding E clause, wherein the second closed fish enclosure comprises a tether, the tether being optionally releasable, to the first closed fish enclosure extending through the enclosed water volume contained between the first closed enclosure and the second closed enclosure.

[0131] CLAUSE E11 . The fish farming structure according to any preceding E clause, wherein the water volume of the first closed fish enclosure has a higher pressure than the water volume of the second closed fish enclosure.

[0132] CLAUSE E12. The fish farming structure according to any preceding E clause, wherein the first closed enclosure comprises an outlet, and the second closed enclosure partially encloses the first closed enclosure around the periphery of the outlet.

[0133] CLAUSE E13. The fish farming structure according to any preceding E clause, wherein the first closed enclosure comprises an outlet, and the fish farming structure comprises a circulation arrangement for circulating water from the first closed fish enclosure to the second closed fish enclosure (e.g. into the intermediate water volume).

[0134] CLAUSE E14. The fish farming structure according to clause E13, wherein the circulation arrangement comprises a water inlet, optionally supported by the floatable structure, to fluidly connect a source of water to the first closed enclosure.

[0135] CLAUSE E15. The fish farming structure according to any preceding E clause, wherein the second closed enclosure comprises a sump at the base thereof, for collecting detritus from the first closed enclosure, optionally via an outlet in the first closed enclosure.

[0136] CLAUSE E16. The fish farming structure according to any preceding E clause, wherein the intermediate water volume comprises a waste removal arrangement for removing waste from the intermediate water volume.

[0137] CLAUSE E17. The fish farming structure according to clause E16, wherein the waste removal arrangement comprises at least one, or a combination of, a gas diffusor, a surface foam skimmer, a sump, a sediment removal conduit, or the like.

[0138] CLAUSE E18. The fish farming structure according to any preceding E clause, comprising a temperature control arrangement or system, wherein the second closed fish enclosure comprises a water inlet and a conduit extending from the water inlet to a location below the second closed fish enclosure, and the temperature control arrangement optionally comprising a heat exchanger for heating of water in a flowpath extending though the water inlet.

[0139] CLAUSE E19. The fish farming structure according to any preceding E clause, comprising a third closed fish enclosure, the first and second closed fish enclosures being located inside the third closed fish enclosure, and a second intermediate water volume located between the second fish enclosure and third fish enclosure, the intermediate water volume at least partially comprising a waste removal arrangement and the second intermediate water volume at least partially comprising a temperature control arrangement.

[0140] CLAUSE E20. The fish farming structure according to any preceding E clause, wherein the collar is configurable to be completely submerged.

[0141] Various further inventive aspects and embodiments according to the present disclosure will now be outlined in the following F-clauses:

[0142] CLAUSE F1 . a fish farming structure for a closed fish farm, comprising: a floatable structure; a closed fish enclosure configurable to be suspended from the floatable structure via a suspension arrangement; the closed fish enclosure comprising a first enclosure and a second enclosure, an enclosed intermediate water volume being defined between the first closed enclosure and the second closed enclosure, the first enclosure configured to permit fluid flow to the second enclosure so as to permit fluid communication between a water volume in the first enclosure and the intermediate water volume; and wherein the fish farming structure comprises a waste removal arrangement comprising a fluid outlet from the first closed enclosure to the second closed enclosure, and a fluid outlet from the second closed enclosure.

[0143] CLAUSE F2. A fish farming structure according to clause F1 , wherein the closed fish enclosure comprises a sump at the base thereof.

[0144] CLAUSE F3. A fish farming structure according to clause F2, wherein the closed fish enclosure defines a fluid outlet at the base thereof, for removal of waste from the sump.

[0145] CLAUSE F4. A fish farming structure according to clause F2 or F3, wherein the base of the fish enclosure has at least one of: an inverted cone shape, inverted pyramid shape, partial or semi-spherical shape and a partial or semi-oblong shape, and a fluid outlet located at the base thereof.

[0146] CLAUSE F5. A fish farming structure according to any preceding F clause, wherein the fish enclosure comprises a gas diffusor therein, and a foam skimmer located at the surface of a water volume contained in the closed fish enclosure.

[0147] CLAUSE F6. A fish farming structure according to any preceding F clause, comprising a first closed fish enclosure and a second closed fish enclosure, the first closed fish enclosure being located within the second closed fish enclosure to define an intermediate water volume therebetween, the waste removal arrangement being located in the intermediate water volume.

[0148] CLAUSE F7. A fish farming structure according to clause F6, wherein a gas diffusor is located in the intermediate water volume, and a surface foam skimmer is located at the surface of the intermediate water volume.

[0149] Various further inventive aspects and embodiments according to the present disclosure will now be outlined in the following G-clauses:

[0150] CLAUSE G1 . A utility structure for a fish farm, the utility structure comprising: a turret configurable to be moored at an offshore location, and being rotatably connected to a supply structure such that the supply structure is rotatable about a central axis of the turret; the supply structure comprising a utility storage and a utility transfer arrangement for transferring a utility between the turret and the supply structure, and the turret comprising a utility connection for transfer of a utility between a fish enclosure and the turret.

[0151] CLAUSE G2. The utility structure of clause G1 , the utility structure being configurable to transfer a utility, wherein the utility comprises at least one of: fish feed, electrical power, compressed air, hydraulic fluid, fish mort and live fish.

[0152] CLAUSE G3. The utility structure of clause G1 or G2, wherein the utility connection comprises a fish transfer conduit for transfer of live fish between a fish enclosure and the turret.

[0153] CLAUSE G4. The utility structure of any preceding G clause, wherein utility transfer arrangement is configurable to transfer a utility from the utility structure to a fish farm.

[0154] CLAUSE G5. The utility structure of any preceding G clause, wherein the utility connection is configurable to be partially or fully submerged in a body of water. CLAUSE G6. The utility structure of any preceding G clause, comprising a dynamic utility connection comprising a turret connection for connecting the dynamic utility connection to the turret, a fish enclosure connection for connecting the dynamic utility connection to a fish farm, and a mid-section extending from the turret connection to the fish enclosure, the entire length of the mid-section being configurable to be suspended in a body of water.

[0155] CLAUSE G7. The utility structure of any of clauses G1 to G5, wherein the utility connection is configurable to be moored to a location in a body of water, such as a seabed.

[0156] CLAUSE G8. The utility structure of any preceding G clause, comprising a refuse connection, for receiving refuse from a fish farm.

[0157] CLAUSE G9. The utility structure of clause G8, wherein the turret comprises a fluid compressor or fluid pump for establishing a flow of refuse from a fish farm to the utility structure, via the refuse connection.

[0158] CLAUSE G10. The utility structure of any preceding G clause, wherein the turret comprises a feed deck, the utility transfer arrangement being configurable to supply fish feed to the feed deck.

[0159] CLAUSE G11. The utility structure of clause G10, comprising a mort handling deck for the processing of mort from a fish farm, the feed deck being located above the mort deck.

[0160] CLAUSE G12. The utility structure of any preceding G clause, wherein the turret comprises a fluid intake for receiving a fluid from a fluid source external to the turret.

[0161] CLAUSE G13. The utility structure of any preceding G clause, wherein the utility transfer arrangement comprises a transport member for supplying dry fish feed to the turret from the supply structure.

[0162] CLAUSE G14. The utility structure of claims G13 wherein the turret comprises a feed processor which processes the dry fish feed (for example by mixing it with a carrier medium) ready for supply to a fish enclosure.

[0163] CLAUSE G15. The utility structure of any preceding G clause, wherein the turret comprises a feed and water mixer unit.

[0164] CLAUSE G16. The utility structure of clause G15, wherein the utility transfer arrangement comprises a transport member for supplying the feed and water mixer unit with dry fish feed, and the feed and water mixer unit is in fluid communication with a water source external to the turret.

[0165] CLAUSE G17. The utility structure of any of clauses G14 - G16, wherein the feed processor or feed and water mixer unit is configurable to prepare and supply a prepared fish feed to a fish farm via the utility connection.

[0166] CLAUSE G18. The utility structure of any of clauses G15 to G17, wherein the turret comprises a water inlet and a water supply conduit for receiving water from a water source, and a fluid pump for transporting water to the feed and water mixer unit.

[0167] CLAUSE G19. The utility structure of any of clauses G13 to G18 wherein the transport member (which may comprise a conveyor or chute) has a first end at the supply structure and a second end which is located above the feed processor / feed and water mixer unit so that feed can fall from the second end of the transport member into the feed processor / feed and water mixer unit.

[0168] CLAUSE G20. The utility structure of any preceding G clause, wherein the utility connection comprises a conduit for providing a fluid connection between a fish farm and the utility structure.

[0169] CLAUSE G21 . The utility structure of any preceding G clause, wherein the utility connection comprises an electrical cable for providing an electrical connection between a fish farm and the utility structure.

[0170] CLAUSE G22. The utility structure of any preceding G clause, wherein the utility connection comprises a plurality of conduits and or cables, and is in the form of a subsea umbilical.

[0171] CLAUSE G23. The utility structure of any preceding G clause, wherein the supply structure comprises a store of dry fish feed.

[0172] CLAUSE G24. The utility structure of any preceding G clause, wherein the turret comprises a swivel arrangement.

[0173] CLAUSE G25. The utility structure of clause G24, wherein the utility transfer arrangement is configurable to transfer fish feed from a plurality of stores of fish feed on the supply structure, each of the plurality of stores of fish feed comprising a different type of fish feed.

[0174] CLAUSE G27. The utility structure of any preceding G clause, wherein the turret comprises a turret storage for storage of a utility therein.

[0175] CLAUSE G28. The utility structure of any preceding G clause, wherein the turret comprises a secondary utility storage.

[0176] CLAUSE G29. The utility structure of clause G27, wherein the secondary utility storage comprises at least one of: a store of fish feed and a store of electrical power.

[0177] CLAUSE G30. The utility structure of any preceding G clause, wherein the turret comprises an electrical control unit for providing a component on a fish farm with an operational instruction.

[0178] CLAUSE G31 . The utility structure of any preceding G clause, wherein the turret comprises power generation means.

[0179] CLAUSE G32. The utility of any preceding G clause, wherein the turret comprises a plurality of circumferentially arranged utility storage compartments.

[0180] CLAUSE G33. A method for providing a utility to a fish farm, the method comprising: mooring a turret of a utility structure in a body of water adjacent a fish farm; transferring a utility between the turret and a supply structure rotatably connected to the turret via a utility transfer arrangement, the supply structure being rotatable about a central axis of the turret; transferring a utility between the adjacent fish farm and the utility structure via a utility connection. CLAUSE G34. The method of clause G33, comprising rotating the supply structure about the central axis of the turret to be parallel to a prevailing environmental direction (wind, wave or current).

[0181] The above describes various examples and aspects, and additional features, some of which are described in relation to the above clauses. It should be noted that a feature described in relation to one aspect or set of clauses may equally be applied to another aspect or set of clauses.

[0182] Hence, it is to be understood that the herein disclosed disclosure is not limited to the particular component parts of the device described or steps of the methods described since such device and method may vary. It is also to be understood that the terminology used herein is for purpose of describing particular embodiments only, and is not intended to be limiting. It should be noted that, as used in the specification and the appended claim, the articles "a", "an", "the", and "said" are intended to mean that there are one or more of the elements unless the context explicitly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" may include several devices, and the like. Furthermore, the words "comprising", "including", "containing" and similar wordings does not exclude other elements or steps.

[0183] BRIEF DESCRIPTION

[0184] The above objects, as well as additional objects, features and advantages of the present disclosure, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of example embodiments of the present disclosure, when taken in conjunction with the accompanying drawings.

[0185] Figure 1 illustrates a known example of a fish farm.

[0186] Figures 2a and 2b are elevation views of a fish farming system.

[0187] Figures 3 and 3b illustrate further details of a suspension arrangement.

[0188] Figures 4a and 4b illustrate an elevation view of examples of an access structure.

[0189] Figures 5a and 5b illustrate a plan view of access of a collar and access structures.

[0190] Figures 6a and 6b illustrate examples of a fish farming system.

[0191] Figures 7a and 7b illustrate further examples of a fish farming system.

[0192] Figures 8a and 8b illustrate an exemplary fish enclosure in further detail.

[0193] Figure 9 illustrates a further example of a fish enclosure in elevation and plan views.

[0194] Figures 10 to 12 illustrate various examples of features of a fish farming system.

[0195] Figures 13a and 13b illustrate further details of a fish farming system.

[0196] Figures 14a and 14b are further examples of a fish farming system comprising a floatable structure. Figures 15a to 15c, 16 and 17a and 17b illustrate a fish farming system comprising a selectively deployable protector.

[0197] Figures 18 to 20 illustrate steps involved in installation of a fish farming system.

[0198] Figures 21a and 21 b show further details of an air pocket structure.

[0199] Figures 22a to 22e illustrate various examples of a floatable structure.

[0200] Figures 23a to 23d and 24a to 24b show further details of an upper and lower structure of a fish farming system.

[0201] Figures 25a to 25c are views of a guide arrangement on a floatable structure.

[0202] Figure 26 shows a schematic elevation view of a fish farming structure.

[0203] Figure 27 is a perspective view of a fish farming structure.

[0204] Figures 28a to 29c are schematic plan views of various fish farming structures.

[0205] Figure 30 is another schematic elevation of a fish farming structure.

[0206] Figures 31a to 31c are schematic plan views of various examples of a fish farming structure, showing some additional features.

[0207] Figures 32a and 32b illustrate an example of a suspension arrangement.

[0208] Figures 33 to 35 show an example of a fish farming structure having a roof enclosure.

[0209] Figures 36 and 37 are examples of a closed fish enclosure.

[0210] Figure 38 is a configuration for removing mort and other waste from a fish enclosure.

[0211] Figures 39a to 39c show further examples of a fish enclosure.

[0212] Figure 40 is a further perspective view of a fish enclosure.

[0213] Figure 41 schematically illustrates the circulation of water within a fish enclosure.

[0214] Figures 42 and 43 are schematic illustrations of configurations of conduits of a fish farming structure.

[0215] Figures 44 to 49b are schematic elevations of various fish farming structures comprising a first and second enclosure.

[0216] Figures 50 and 51 illustrate circulation of water in an intermediate volume of a fish farming structure.

[0217] Figure 52 illustrates a fish farming structure having a first and second enclosure, where the one enclosure is water permeable, and one comprises a single outlet.

[0218] Figure 53 is a fish farming structure having a temperature control system. Figures 54 to 57 illustrate examples of a protector for preventing damage to a fish farming structure.

[0219] Figures 58a-c schematically illustrate two examples of a utility structure.

[0220] Figure 59 illustrates a utility structure connected to a fish farm.

[0221] Figure 60 shows a schematic illustration of a turret.

[0222] Figures 61a-e are views of a deck on a turret.

[0223] Figure 62 is a further schematic illustration of an example of a turret.

[0224] Figure 63 is a further plan view of a utility structure, showing more detail of a supply structure.

[0225] Figures 64a and 64b are sectional elevation views of examples of utility structures.

[0226] Figure 65 is a further schematic illustration of a utility structure, showing a line connecting the turret and supply structure.

[0227] Figure 66 Illustrates steps involved in the disconnection of a supply structure from a turret.

[0228] DETAILED DESCRIPTION

[0229] The following description may use terms such as “horizontal”, “vertical”, “lateral”, “back and forth”, “up and down”, ’’upper”, “lower”, “inner”, “outer”, “forward”, “rear”, etc. These terms generally refer to the views and orientations as shown in the drawings and that are associated with a normal use of the invention. The terms are used for the reader’s convenience only and shall not be limiting.

[0230] A first aspect of the present disclosure relates to a fish farming system comprising a floatable structure comprising a collar and an access structure, a fish enclosure, which in use contains a plurality of fish, is suspended from the floatable structure via a suspension arrangement so that an uppermost portion of the fish enclosure is spaced from a lowermost edge of the floatable structure. According to some examples the collar may define an access opening centrally therein for providing access to the fish enclosure through the collar. The collar is configurable to be submerged in an exposed open-water location, such as an offshore location. The access structure is located on the collar, and is configurable to extend from a submerged location at a point of contact with the collar, to a location above the waterline, for example to permit raising and lowering of the fish enclosure relative to the collar.

[0231] In use, the collar may be normally submerged in an offshore location, with only the access structure protruding above the waterline and providing a user access the fish farming system (e.g. the fish enclosure and / or the floating collar). The floating collar being submerged may assist to reduce the impact of forces from the surrounding water on the fish farming system (e.g. forces on the collar or on the fish enclosure suspended below the collar), such as forces from waves, and may offer other benefits to a user, as will be described herein. Conventional fish farming systems may comprise a collar that experiences a large degree of motion floating on the surface of a body of water, and is exposed to forces as a result of waves on the surface. As such, these conventional systems may be suitable for operation only in sheltered locations, where the impact of waves on the fish farming system is relatively small. By having a fish farming system comprising a submerged collar, the collar is shielded from surface waves, thereby reducing wave forces incident on the collar, and permitting the fish farm system to be located in waters that are less sheltered.

[0232] Figure 1 illustrates a known example of a fish farm 1 , as is disclosed in International application No. PCT / N02021 / 050128. Here, the fish farm 1 comprises a fish enclosure with a floating collar 2 comprising a lower ring 7, and upper ring 9, connected by a plurality of columns 8. The fish farm 1 comprises a net cage 3 suspended from the floating collar 2. In use, the floating collar 2 may be located on the surface of a body of water, while the net cage 3 extends below the floating collar 2. The entire floating collar 2 may therefore be exposed to surface waves, which in open waters can be very large, and use of the fish farm 1 may be restricted to locations where the magnitude of waves is known to be limited.

[0233] In Figure 2a, there is illustrated an example of a fish farming system 100 according to the present disclosure, shown in cross-sectional elevation. In this example, the fish farming system 100 comprises a floatable structure 101 , which in this example is a semi-submersible structure (e.g. comprising a submerged portion, and a nonsubmerged portion), although in other examples may float on the surface. The fish farming system 100 of this example may therefore be considered to be a semisubmersible fish farming system.

[0234] Although not illustrated in this example, mooring lines may be connected to the floatable structure 101 (e.g. to the collar 102 or the access structure 108, as will be described) to hold the floatable structure 101 in a desired location. The mooring lines may be arranged in a frame mooring or an independent mooring system.

[0235] The floatable structure 101 comprises a collar 102 from which a fish enclosure 104 is suspended via a suspension arrangement 106. The floatable structure 101 may be buoyant. The collar 102 may be a buoyant collar. The fish enclosure 104 may be suspended below the floatable structure 101 , e.g. entirely below the floatable structure 101. Suspending the fish enclosure 104 via a suspension arrangement 106 so that the uppermost portion of the fish enclosure is below the lowermost edge of the floatable structure 101 may assist to keep the fish enclosure at a desired depth in the body of water, offering many benefits. For example, algae, pathogens and lice may thrive near the water surface, for example due to access to sunlight and oxygen, and because of proteins and fats that are more abundant at the water surface. Further, holding the fish enclosure 104 away from the surface (e.g. the waterline) reduces the risk from surface hazards such as oil or fuel spills, floating debris, seafaring vessels, surface ice, aerial predators which may pose risk at the surface. Fish in a fish enclosure held at depth may also be at a reduced risk of being stolen, as they may be more difficult to access without specific equipment. The fish may also experience other benefits from being held away from the surface, for example a more stable water temperature year-round, thereby improving the welfare of the fish, increasing their growth rate and capacity.

[0236] In another example, the collar 102 may comprise at least one buoyancy member as part of the structure or connected thereto, for example tied or bolted thereto. In some examples the collar 102 may comprise a plurality of buoyancy members connected thereto, for example two, three, four or more buoyancy members. The at least one buoyancy member may be in the form of a closed void / chamber or air-filled compartment which again may be in the form of a tank comprising an opening (and optionally a valve therein) for permitting entry and exit of a fluid (e.g. water) therefrom. Additionally or alternatively, the at least one buoyancy member may comprise a buoyant material, such as a buoyant foam or cellular material. In some examples, the entire collar 102 may be considered to be a floater. For example, the collar may be hollow or comprise a cavity therein providing buoyancy to the collar 102, and that is able to be filled and emptied of air and / or water if desired, e.g. the collar 102 may be able to be ballasted.

[0237] The collar may comprise perforations (e.g. apertures, slots, or the like) therein, or comprise one or more perforated portions, for example the collar 102 may comprise a portion thereof that comprises a grate or truss structure (see Figure 7b, for example). Having one or more perforations or perforated portions may permit water to flow through the collar 102, thereby reducing the impact of water currents and waves on the collar, and permitting self-adjustment of the buoyancy of the collar 102 by permitting water to flow into and from the collar as it rises above and falls below the waterline (e.g. flow under the force of gravity or a differential in relative density between, air and water).

[0238] Unless otherwise stated, the term “buoyant” should be understood to mean positively buoyant.

[0239] The floatable structure 101 (e.g. the collar 102 of the floatable structure 101 may be rigid). In open water (e.g. offshore), having a rigid floatable structure 101 may greatly reduce or remove the deformations of the floatable structure 101 as a result of wave motion. Reducing the deformations of the floatable structure 101 may similarly reduce deformations and load concentrations on an attached fish enclosure, thereby having a protective effect on the fish enclosure (as compared to an example in which the floatable structure is flexible, for example).

[0240] The floatable structure 101 also comprises an access structure 102 located on, and extending from, the collar 102. The access structure 108 may extend vertically from the collar 102, in this example vertically upwardly. The access structure 108 extends above a waterline 110, while the collar 102 is fully submerged (i.e. substantially all the collar 102 is located below the waterline). The floatable structure 101 therefore comprises a submerged portion (the collar 102 and a lower section of the access structure 108) and a portion above the waterline (an upper section of the access structure 108) and therefore the floatable structure 101 can be considered to be a semi-submersible structure. The access structure 108 may connect to the collar by any appropriate means, for example by bolting, welding, chemical bonding or the like. The access structure 108 may be integrally formed with the collar 102, in which case the connection between the access structure 108 and the collar 102 may be defined by a change in geometry of the annularly structured collar 102 and the geometry of the access structure 108, which may be a column or prism shape.

[0241] As is illustrated, the collar 102 is completely submerged, and in some examples at least part of the collar 102 may be configurable to be located above the waterline, for example at least temporarily (such as during maintenance and inspection of the collar 102). In Figure 2b, there is illustrated an example in which the floatable structure 101 floats on the waterline, and neither the access structure 108 nor the collar 102 are fully submerged. In this example, the floatable structure may not be considered semisubmersible, and may be considered a surface-floatable structure. Alternatively, the structure of Figure 2b may be considered to be a semi-submersible structure configurable between a submerged and a non-submerged configuration, illustrated in the non-submerged configuration which may be for facilitating maintenance and inspection. The submerged configuration may be an operational draft of the floatable structure 101 , while the non-submerged configuration may be considered to be a temporary or maintenance draft of the floatable structure 101 . The floatable structure 101 may be configurable between a first and a second draft, which may be the operational draft and maintenance draft.

[0242] In one example, an upper surface of the collar 102 may typically be located 3 metres below the waterline 110, while a lower surface of the collar 102 may typically be located 6 to 9 metres below the waterline 110. This should be considered one example embodiment; other embodiments could be significantly deeper or significantly shallower. The actual depth of the upper and lower surfaces of the collar may vary depending on the size of the cage, and the expected environmental conditions. As the access structure 108 extends above the waterline, a user may be able to use this structure to locate the fish farm 100 and also to access another part of the fish farm 100 (e.g. via a communication line, winch etc. as will be described). A user may be able to board / mount the access structure 108 to facilitate access to another party of the fish farm 100 (e.g. an enclosure thereof). Additionally, having the collar 102 completely submerged may reduce the magnitude of forces acting on the suspension arrangement 106 due to external forces, such as wave motion. The reduced water plane area from access structures 108 compared to the collar 102 will change the motion response of the floatable structure 101 . For example, motion of the submerged collar 102 may be reduced (and may also be damped) compared to that of a collar that floats on the surface, for example because forces from wave motion on the floatable structure 101 diminish with depth, and will therefore be lesser on submerged parts of the structure.

[0243] Further, the floatable structure 101 may comprise a self-ballasting arrangement, for example comprising at least one self-ballasting structure (e.g. in the form of a container or tank) with openings therein which will be filled with water when submerged. The self-ballasting structure may therefore be in the form of a soft tank. The self-ballasting structure may be or comprise an open cavity, compartment or the like that is able to be filled with water via an aperture therein, once the self-ballasting structure is submerged below a waterline. The at least one self-ballasting structure may be located on the collar 102 or the access structure 108, and in some examples there may be a plurality of self-ballasting structures. In such examples, having the collar 102 at a submerged location will effectively increase the mass of the floatable structure 101 by permitting the self-ballasting structures to fill with water, and therefore increase the inertia of the floatable structure 101 and reduce excitation and sudden movements of the floatable structure 101 , for example caused by wave motion. This may be achieved without the need to pump fluid, as the tank will ballast naturally with a flow of water through an aperture, e.g. an open aperture. As such, having the collar submerged 102 may reduce sudden and / or jarring forces (snap loads) on the suspension arrangement 106, thereby prolonging the life of the suspension arrangement 106 and reducing the risk of sudden failure thereof.

[0244] The at least one self-ballasting structure may be able have an opening, or the openings, thereof blocked by a user, thereby permitting a user to choose whether the self-ballasting structures should be free to fill and empty as they are submerged, or whether the self-ballasting structures should have a fixed buoyancy. A user may therefore be able to use the self-ballasting structures to vary key properties (e.g. structural properties) of the floatable structure 101 to achieve optimised hydrodynamic and stability properties that are tailored to the requirements of the fish farming system. Further, the user may minimize the required energy to change draft of the structure.

[0245] The access structure 108 may be buoyant. For example, the access structure 108 may comprise at least one buoyancy member, and / or floater as described above in reference to the collar 102. In some preferred examples, the access structure 108 may be buoyant, or configurable to be buoyant, thereby providing buoyancy to the floatable structure 101. In such examples, the access structure 108 may have positive buoyancy, while the collar 102 has a positive, neutral or negative buoyancy. The access structure 108 may provide substantially all of the positive buoyancy of the floatable structure 108, or may provide a majority of the positive buoyancy of the floatable structure.

[0246] The floatable structure 101 may be buoyant (or comprise a degree of buoyancy) such that the collar 102 is configurable to be completely submerged, while the access structure 108 (or plurality thereof) is configurable to extend above a waterline from the collar 102. For example, the buoyancy of the access structure 108 or structures and the buoyancy of the collar 102 may be adapted or selected so as to provide the floatable structure 101 to permit the collar 102 to be completely submerged in a body of water, and for the access structure 108 or structures to extend above the waterline of the body of water. As previously described, at least one of the collar 102 and the access structure 108 or structures may be positively buoyant, one of the collar 102 and the access structure 108 may be positively buoyant and the other negatively buoyant, or the like, in order to provide the floatable structure 101 with the desired degree of buoyancy. In the example of Figures 2a and 2b, the access structure 108 is in the form of a plurality of columns (e.g. pillars) extending upwardly from the collar 102. At least one, or each, of the plurality of columns may extend vertically upwardly from the collar 102, or may extend upwardly at an oblique angle to the collar 102 (e.g. relative to an upper surface, or to a circumferentially or peripherally extending axis through the centre of the collar structure). The plurality of columns of the access structure 108 may be equidistantly spaced around the collar, or may be located in a plurality of groupings of two or more columns (where the columns in each grouping are adjacently located).

[0247] In some examples, the columns of the access structure 108 may extend both above and below the collar 102, as is illustrated in Figure 2a, which may be preferable with respect to structural design or fabrication.

[0248] In having a semi-submersible fish farming system 100 as described above the area of the fish farming system 100 that intersects the waterline (e.g. the water plane area) may be reduced. In some examples, only the access structure 108, which may comprise a plurality of vertically and / or obliquely oriented columns, intersects the waterline, thereby reducing the water plane area as compared to examples in which the entire collar 102 intersects the waterline. Reducing the water plane area will change the response of the floatable structure 101 in waves, reduce wave loads and may be preferable in icy conditions to minimise ice formation on the floatable structure 101.

[0249] Although in this example, the entire collar 102 is submerged, it may be possible to provide examples in which at least a part of the collar 102 emerges above the waterline 110. In addition and as previously described, the floatable structure 101 may operate on several drafts, including at least one temporary draft configuration where at least a part of the collar 102 emerges above the waterline, and at least one other operational draft configuration, for example where the collar 102 is fully or optionally partially submerged. This may be beneficial for inspection, modification and farming operations.

[0250] In this example, the suspension arrangement 106 extends between the floatable structure 101 and the fish enclosure 104. In this example, a lower part 106a of the suspension arrangement 106 extends between the access structures 108 and the fish enclosure 104 and is in the form of an elongate member. Here, an elongate member, which may be or form an upper part 106b of the suspension arrangement 106, extends between the collar 102 (e.g. a lower surface of the collar 102) and to the access structure 108, for example, the upper half of the access structure 108, or the part of the access structure 108 that is configured to be located above the waterline. The suspension arrangement may comprise a plurality of elongate members. The suspension arrangement 106 may be or comprise a flexible member (e.g. a flexible elongate member) such as a wire, cord, chain, rope or the like. A flexible member may have low bending stiffness. In some examples, the suspension arrangement may be or comprise a rigid member (e.g. a rigid elongate member) such as a rod, pipe, rail, rack or the like, which may extend between the collar 102 and the fish enclosure 104. A rigid member may have high axial stiffness. In some examples, the suspension arrangement may comprise a combination of flexible and rigid members, for example the suspension arrangement may comprise a rigid member extending between the access arrangement 108 and the collar 102, and a flexible member extending between the collar 102 and the fish enclosure 104.

[0251] The suspension arrangement 106 may comprise a plurality of sets of upper and lower parts 106a,b (e.g. a plurality of sets of elongate members) extending between the floatable member 101 and the fish enclosure 104. The number of sets of upper and lower parts 106a,b may connect at equidistant points to the fish enclosure 104 and / or the collar 102 of the floatable structure 101 . The number of sets of upper and lower parts 106a,b may correspond to the number of apexes in the horizontal cross-section of the collar and / or upper structure 112. Each apex may comprise a connection point to the suspension arrangement 106.

[0252] The access structure 108 or the collar 102 may comprise a height adjustment means 107 for raising and lowering of the fish enclosure 104 relative to the collar 102. The height adjustment means 107 may be used to vary the length (e.g. increase or decrease) of the suspension arrangement 106. The height adjustment means may therefore comprise a winch located on the floatable structure 101 which may be used to reel in, or pay out, a length of suspension arrangement 106, e.g. cable, rope or the like. Here, no winch is illustrated, and the upper part of the suspension arrangement 106b may comprise a connector or connection point and / or profile to a winch or to a barge, on which a winch or similar apparatus may be located. Therefore the height adjustment means 107 may be or comprise a connector and / or connection point / profile to a winch or barge. In this example, the elongate member of the upper suspension arrangement 106b permits a user easy access the suspension arrangement 106 from the access structure 108, and therefore to raise and lower the fish enclosure 104 from the access structure 108. The height adjustment means 107 may therefore be located on the suspension arrangement 106, and may cooperate with the suspension arrangement 106 to adjust the height of the fish enclosure 104 relative to the floatable structure 101 . In other examples, the suspension arrangement 106 may be separate from the height adjustment means 107 (see Figure 10) and the height adjustment means may comprise an elongate member for raising and lowering the fish enclosure 104. Access to the fish enclosure 104 may involve the user being able to raise or lower the fish enclosure 104 relative to the collar 102, for example for the purpose of cleaning, removing fish therefrom, etc.. The fish enclosure 104 may be raised to the elevation of the collar, or at least a portion of the fish enclosure 104 may be raised higher than the elevation of the collar. Having such a suspension arrangement 106 may remove the need to submerge the collar 102 at the same depth as the fish enclosure 104, and may permit the collar 102 to be submerged at a much more shallow depth than would otherwise be necessary, while still permitting the fish enclosure 104 to be submerged to a desired depth which is deeper than that of the collar 102 (e.g. if the fish enclosure 104 were to be connected directly to the collar 102).

[0253] The suspension arrangement 106, such as the lower part 106a of the suspension arrangement 106, may require to be more robust (for example it may have a larger diameter or be made from a stronger material), as the weight of the fish enclosure 104 may be supported by the lower part of the suspension arrangement 106a during operation, and may need to be strong enough to endure storm conditions, corrosion, fatigue, wear and tear etc.. In comparison, the upper part of the suspension arrangement 106b, may be less robust, for example may have a smaller diameter and / or lower stiffness and may be used more easily for the purpose of raising and lowering the fish enclosure 104 relative to the collar 102. A less robust elongate member may be easier to handle (e.g. on a winch, fairlead etc.) and may be easier to store. For example, not only will a smaller diameter mean a smaller elongate member, it also may require a smaller winch, smaller guide wheels, a smaller chain locker etc., which may also be easier to transport. In this example, the height adjustment means connects directly to the suspension arrangement 106.

[0254] As illustrated in Figure 2a and as previously described, the access structure 108 is in the form of a plurality of columns which extend from the collar 102. Here, two are shown, although there may be more or fewer, depending on the design of the fish farm 100, as will be described in more detail in the following paragraphs.

[0255] The vertical cross-section 120 of the collar 102 is visible in Figure 2a, and in this case is circular, although other shapes of cross-section may be possible and / or desirable. For example, the cross-section 120 may be rectangular, triangular, polynomial, or any other desired shape (see, for example, Figure 22a). The entire height of the vertical cross-section of the collar 102 is submerged, and varying the shape of the crosssection may have an effect on the hydrodynamic forces acting on the collar 102 as the fish farm 100 moves in water. The shape of the cross-section may vary along the length of periphery of the collar, or circumferentially in the case where the collar has a ring shape. For example, the area and / or shape of the cross-section of the collar 102 may vary along the length of the periphery (or circumferentially) of the collar 102.

[0256] The collar 102 may have a horizontal cross-section in the form of a ring (and therefore in this example have a toroidal form), or may be in the form of a square frame, pentagonal frame, or any other polygonal shape. The horizontal-cross section may be a C- or U-shape, or an annular shape with one or at least one break or discontinuity therein, for example so as to form a C- shape or similar. The shape of the collar 102 may be such as to define a central void, for example an annular shape such as a ring, or a polygonal annular shape, such as a square, a pentagon, a hexagon or the like. The polygon may be regular or irregular. The collar 102 may therefore define an access opening therein, through which a user may be able to access the fish enclosure. It should be noted that the user may be able to access the fish enclosure by means other than through the access opening, for example from a side angle, from outside of the collar etc..

[0257] The collar 102 may be formed from one continuous member, e.g. one continuous ring-shaped member. In another example, the collar 102 may be formed from a plurality of members, e.g. elongate structures, which may be connected together to form the collar 102. The plurality of structures may be a plurality of straight elongate structures, a plurality of curved elongate structures, or a mixture of at least one straight and at least one curved elongate structure. At least one of the structures may comprise perforations, in some examples, at least one, or each, of the structures may comprise a truss structure. The collar 102 may be in the form of a pontoon, or a plurality of connected pontoon members. The collar may comprise at least one buoyancy member e.g. located therein or defined thereby, which may be integrated within the or a member that forms the collar 102, or which may be connected or fastened to the member that forms the collar 102. The at least one buoyancy member may be integrally formed with the collar 102, such that it may be considered to be a buoyant collar.

[0258] Although not illustrated, at least one of the collar 102 and the access structure 108 may comprise a ballast tank therein in some examples, which may optionally be able to be ballasted and deballasted by a user. For example, a plurality, or each, of the access structures 108 may comprise a ballast arrangement comprising at least one ballast tank that is able to be ballasted and deballasted to control the buoyancy of the floatable structure 101 . The level of buoyancy and positioning of such ballast tanks may be selected so as to ensure that the collar 102 remains submerged at all times, or when desired, and at an appropriate level below the waterline 110 (e.g. 3 metres below the waterline), thereby assisting to ensure that the collar 102 obtains the desired hydrodynamic properties. Additionally, the ballast level of the ballast tanks may be decreased such that the collar 102 is no longer fully submerged, which may be useful for transport and maintenance, for example. The level of ballast in the ballast tanks may be selected by pumping surrounding seawater into and out of the ballast tanks, and may be variable by a user when desired. Each ballast tank may therefore comprise a pump and caisson, at least part of which may be located in at least one of the access structure and the collar. The user may therefore be able to vary the depth of the collar 102 below the waterline, which may permit further variability of the hydrodynamic and stability properties of the floatable structure 101 .

[0259] As previously described the collar 102 may comprise perforations, or a perforated portion. In such examples, the collar may be neutrally or negatively buoyant, and may be intended and designed to optimise its structural and hydrodynamic properties, for example by including perforations therein.

[0260] The fish enclosure 104 of the example of Figure 2a comprises an upper structure 112 and a lower structure 114, which are connected by the boundary material (e.g. the net 116), and optionally some tensioned ropes, wires or cables 118. Both the upper structure 112 and the lower structure 114 may be located below the floatable structure 101 , for example below the collar 102 thereof. In order to keep the net 116 taught the lower structure 114 may have negative net buoyancy, causing it to exert a downwards force on the net 116, and to tension the cables 118 and the net 116. Having tension in the net 116 may assist to stabilise the position of the net 116, maintain the shape of the net and limit snap loads. The upper and / or lower structure may be in the form of a frame, e.g. a rigid frame. The upper structure may have an annular shape, e.g. a circular annular shape, a square or rectangular annular shape, a polygonal annular shape. The shape of the upper and / or lower structure may be similar or the same as that of the collar 102. The upper structure 112 may have positive, negative or neutral net buoyancy and may function to directly connect the fish enclosure 104 with the collar 102. The upper structure 112 may therefore assist to transfer load between the wires, ropes or cables 118 of the suspension arrangement 106 and the net 116, while the lower structure may function to transfer load between the net and the weight of the lower structure (e.g. as a result of its inherent weight, or as a result of weights that have been positioned thereon or therein). The negative buoyancy of the lower structure 114, combined with the optional positive buoyancy of the upper structure, may assist to prevent vertical collapse of the fish enclosure 104. Further, the upper and / or lower structure 112, 114 may be rigid, which may therefore also prevent horizontal collapse of the fish enclosure 104. As will be described, the configuration of the net may be variable, as may be the configuration of the upper and lower structures 112, 114. Further, although both an upper and a lower structure are illustrated 112, 114, in some examples there may be only one of the lower and upper structures 112, 114.

[0261] In order to reduce the risk of fish in the fish enclosure being infested with sea lice, the upper structure 112 of the fish enclosure 104, under normal operation, may be held at a depth of e.g. around 25 metres below the waterline 110. As has been explained, reasons such as sea lice being most dominant at the surface and in the upper 4 to 10 metres of the water column mean that it is desirable to hold the fish enclosure 104 below this depth.

[0262] In some examples, the design and dimensions of the fish enclosure 104 may be varied (e.g. the length of the suspension arrangement 106, the depth of the fish enclosure 104, the size of the upper and or lower structures 112, 114, or the like) so as to vary the natural period (e.g. natural frequency) of the fish farming system 100, so as to obtain a natural frequency that is minimally affected by the surrounding environment. For example, the suspension arrangement 106 may experience pendulum motion, and as such the length of the suspension arrangement 106 may be selected to avoid this phenomenon occurring at frequencies where there may be significant wave energy.

[0263] Figure 3 illustrates an example of an access structure 108 comprising a suspension arrangement 106 having an upper part 106b and a lower part 106a in further detail. Here, the upper part 106b is schematically illustrated as being attached to a pulley and winch mechanism 122, which is mounted to the access structure 108 (although in other examples the pulley and winch mechanism 122 may at least partially be mounted on a vessel). In some examples, the upper part 106a may comprise a connector or connection profile for connecting to an elongate member such as a cable, rope or the like on a winch. Having such a mechanism on the access structure 108 may permit a user to raise and lower the fish enclosure 104 from the access structure 108, which is located above the waterline 110 and may be easily accessible to a user (e.g. from a boat or platform). The upper part 106b passes from the pulley and winch mechanism 122, through a bracket 124 which may enable movement of the upper part 106b relative to the access structure 108 without damage thereto. The upper part 106b passes through the bracket 124 (in this example, approximately parallel to the column of the access structure 108, and through a restrictor 126). For the restrictor 126 to be effective, the elongate member 106b has a corresponding stopper 128. The stopper 128 comprises a profile which mates with an aperture in the restrictor 126, and has the effect of restricting downward movement of the upper part 106b relative to the access structure. As such, the stopper 128 and the restrictor 126 may together form a hang-off arrangement. The upper part 106b located above the stopper 128 may be less robust than the lower part 106a which may be located below the stopper 128, as previously described. In this case the lower part 106a comprises the more robust elongate member. In addition, the restrictor 126 functions to hold the upper part 106b away from the access structure 108 and / or the collar 102, and therefore prevents damage to the access structure 108 from the upper part 106b or vice versa. For example, in the instance that the upper part 106b drifts laterally relative to the collar 102, then the upper part 106b will not be pressed against the collar 102 and / or access structure 108.

[0264] Figure 3b illustrates an example of a restrictor 126 in an elevation and plan view. In this example, it can be seen that the restrictor comprises a seat that has a U- or a C- shape, or in some examples keyhole shape (i.e. having a circular portion connecting to a rectangular or triangular shaped portion), and thereby is capable of seating the stopper 128 therein when the elongate member is located in (e.g. threaded through) the seat. The shape of the seat may also enable the upper part 106b to be removed from the seat (e.g. such that it is no longer threaded therethrough), which may be a necessary in situations where it is desired to raise the enclosure, for example.

[0265] An object 130, which may be the upper structure 112 (e.g. in cross-sectional view), is illustrated on the suspension arrangement 106. As is illustrated, above the object 130 there is a change in the angle of the suspension arrangement 106, resulting from the object 130 and the aperture in the restrictor 126 not being aligned. As the object 130 (e.g. the upper structure) is raised and brought closer to the restrictor 126, the C- or U-shaped nature of the restrictor 126 may permit the suspension arrangement 106 to disengage or be released from the aperture in the restrictor 126, thereby preventing damage to the suspension arrangement 106 or the restrictor 126 as the suspension arrangement and attached fish enclosure 104 are raised. Although illustrated as being perpendicular to the column (e.g. the longitudinal axis of the column) of the access arrangement 108, the restrictor 126 may be positioned obliquely relative to the column, which may provide a preferential arrangement for seating of the stopper 128, for example.

[0266] As well as there being the possibility that the pulley and winch mechanism 122 could be mounted on a vessel, equally the fish enclosure 104 may be serviced from a vessel. In such a scenario, the vessel would provide electricity, feed, control communications etc. to the fish enclosure 104. In other examples, the enclosure may be independent, in which case no vessel is needed for service purposes.

[0267] Figures 4a and 4b, and 5a and 5b illustrate possible variations to the structure of the collar 102 and the access structures 108. In Figures 4a and 4b, the cross-section 120 of the collar 102 has been altered. In Figure 4a, although the collar 102 still has a circular cross-section, the collar comprises a collar extension 102a, which extends radially of the collar 102. In this case, the collar extension 102a extends radially outwardly of the collar 102, although in some examples, the collar extension 102a may extend radially inwardly. The collar extension 102a may be considered to be in the form of a heave plate, which may assist to increase the drag of the collar in a body of water and increasing the vertical hydrodynamic added mass of the collar when submerged. The collar extension 102a may be completely submerged in normal operation, or at least a part thereof may emerge from the waterline 110.

[0268] In the case of Figure 4b, the collar cross-section 120 has a square shape. In both cases, the shape of the collar cross-section 120, and the optional collar extension 102a may be constant with the length of the collar 102 or may change with the length of the collar 120. In both cases, the resulting collar geometry may result in a collar that creates more drag when travelling through the surrounding water, and alter the natural period of the system 100 in the body of water. The collar 102 geometry may therefore have a damping effect on the motion of the collar in the water. As such, this collar cross section 120, and / or collar extension 120a may permit the collar to be used with less risk to damaging the elongate member 106b as a result of rapid and / or jerky movements of the collar 102 in the water.

[0269] Although the access structures 108 are illustrated in this example as having a circular cross-section, any other appropriate cross-section may be possible. For example, the access structures 108 may comprise a triangular, rectangular, square, polygonal, or any other desired cross section. The cross-section of the access structures 108 may be varied to increase the structural strength of the access structure 108, and may additionally assist to vary hydrodynamic forces acting on the access structures, and therefore the floatable structure 101 as a whole. Therefore, the geometry of the access structure may be varied depending on the requirements of the user.

[0270] In Figures 5a and 5b, a further two examples of floating collars 102 having differing configurations. Both are shown in a plan view, with the fish enclosure 104 located in the middle of the collar 102. Although both collars 102 are shown in this example to have a square shape, the skilled reader will understand that other configurations of collar 102 are also possible.

[0271] In both Figures, the collar 102 comprises a plurality of access structures 108. In the case of Figure 5a, the access structures 108 are located adjacent the structure of the collar 102, and may be connected thereto at a point along the length of the access structure 108. The access structures 108 may be considered to be located radially inwardly of the collar 102.

[0272] Figure 5a additionally shows one access structure 108 that is located on the collar 102, and in Figure 5b, all the access structures 108 are located on the collar. Varying the position of the access structures 108 relative to the collar 102 may provide differing benefits to a user. For example, having access structures 108 located radially inwardly of the collar (as in Figure 5a) may enable a user to connect the fish enclosure 104 to the access structure while providing a horizontal offset between the fish enclosure 104 and the collar 102, thereby reducing the likelihood of collision of the fish enclosure 104 with the collar when raising and lowering the fish enclosure 104. Having the choice between positioning the access structures 108 located on (e.g. on top of) the floating collar 102, or inside and adjacent the floating collar may allow the stiffness of the structure to be varied in heave, pitch and roll, thereby changing the hydrodynamic and stability properties, which may therefore affect hydrodynamic and stability properties, depending on the requirements of the system 100 (e.g. based on the location of the system 100). A user may be able to design the system 100 to have preferred properties.

[0273] The access structures 108 may comprise a feed silo or silos (as in Figure 7a, for example), comprising a volume of fish feed. Additionally or alternatively, a feed silo may be contained in, or located on, the collar 102 in a separate silo structure.

[0274] Further, the collar 102 may comprise auxiliary support structures 111 (e.g. truss structures) that extend between two points on the collar 102 (e.g. between two elongate structures of the collar), between two of access structures 108, and / or between an access structure 108 and the collar 102. An example of a support structure 111 extending between two access structures is illustrated in Figure 6a. The support structures may assist to increase the structural rigidity of the floatable structure 101 , and may be used to provide support, protection and routing of cables, pipes, hoses and other equipment mounted on the floatable structure 101. The support structure(s) 111 may be located at the level of the collar, or above the level of the collar 102, such as at the top of the access structure 108 and therefore may be considered to be upper support structures 111. The auxiliary support structures 111 may additionally function as a hang-off system for the fish enclosure from the collar, and may facilitate handling of the fish enclosure (e.g. the net of the fish enclosure) during installation. Additionally, the auxiliary support structures 111 may be used as a hang-off for lice skirts, as will be described in the following paragraphs. In the example of Figure 6a, the auxiliary support structure 111 is connected by a strut 113 to the collar 102 for additional support. Further illustrated, the auxiliary support structures 111 may be used as mounting surfaces for equipment 115, or for superstructures or containers for the equipment, feed, or the like.

[0275] Additionally or alternatively, the collar 102 may comprise a walkway and / or platform 117 located thereon (see Figure 6b), and may comprise walkways spanning across the centre recess of the collar 102, thereby facilitating a user to walk along and access different parts of the collar 102, and platforms, for example enabling a user to store equipment, or to access a central location of the collar. In doing so, the user may be more easily able to access the fish enclosure 104, the access structures 108 (and e.g. any feed silos located therein). In some examples, an auxiliary support structure 111 may additionally function as a walkway, or may support a walkway and / or platform 117.

[0276] Figures 7a and 7b illustrate further adaptations or additional features that may be included on the floatable structure 101 . For example, Figure 7a illustrates a support member 119 extending at a diagonal between an access structure 108 and the collar 102. Also illustrated is a housing 125 located on (here, at the top of) an access structure 108. The housing 125 may be a container, for example for equipment, a room, a topside, a superstructure, or the like, which may be accessible by personnel, and which may be capable of holding one or multiple personnel, for example personnel who are performing maintenance or other operations. The housing 125 may be simply mounted to the access structure 108, or may be integrated therein (for example, may extend into the access structure 108 and / or may be partly defined by the access structure 108). The housing 125 may be permanently or temporarily mounted to the access structure 108. The housing 125 may be used to store equipment, and in some examples, may be used to store feed. Although not illustrated, the housing 125 may comprise a feed conduit or conduits extending therefrom, which may extend from the housing 125 to the fish enclosure 104, and which may provide a supply of food to the fish enclosure 104. The housing 125 may therefore be used as a means to supply the submerged fish enclosure 104 with food, while also being easily accessible (e.g. for replenishment) by a user. Although only one housing 125 is illustrated in this example, the system 100 may comprise a plurality of housings 125 mounted on the floatable structure 101 , each of which may comprise a feed conduit, and may be independently operable to provide feed to the fish enclosure.

[0277] Additionally or alternatively, the or each housing 125 may be used to store equipment such as air compressors, power units, control systems or the like. Having such equipment as part of the fish farming system 100 may provide for a system 100 that is self-sustaining to some degree. For example, the fish enclosure 104 may be able to be suspended below the waterline and provided with a supply of feed for a prolonged period without requiring user-intervention. Additionally or alternatively, the equipment provided in the housing 125 may be able to be used in combination with systems on a barge or vessel (e.g. with power and / or control systems that permit operation of the equipment in the container 125).

[0278] Additionally, Figure 7a illustrates a spring arrangement 121 which connects the floatable structure 101 to the fish enclosure 104. The spring arrangement 121 may be in the form of an elastic rope or cable that connects the floatable structure 101 to the fish enclosure 104, and in this example comprises a plurality of elastic cables that extend diagonally from one end of the floatable structure 101 to the oppositely disposed end of the fish enclosure 104. In other examples, the elastic rope or cables may extend directly (e.g. downwardly) between the fish enclosure 104 and the floatable structure 101.

[0279] Figure 7b illustrates an example in which the collar comprises a frame (e.g. a truss) structure. As such, the collar may be considered to be perforated (in this case, the perforations being provided by the nature of the gaps in the truss structure), and may permit the flow of surrounding water therethrough. In this illustration, the truss structure comprises a plate 123, which may be a heave plate, positioned thereon. Additionally or alternatively, an access structure 108 may comprise a plate 123, which may be located on a bottom or lower surface thereof, as illustrated. The plate 123 may function to increase hydrodynamic damping by increasing the hydrodynamic added mass of the collar 102. A similar plate is shown attached to the access structure in Figure 7b, which may function in a similar way to the collar extension 102a illustrated in Figure 4a.

[0280] Figures 8a and 8b illustrate a side view of an example of a fish farming system 100. As in previous examples, the fish farming system 100 comprises a collar 102 comprising access structures 108, with a fish enclosure 104 being suspended from the collar 102 under the waterline 110. Figures 8a and 8b illustrate two different examples of fish enclosure 104. In the example of Figure 8a, the fish enclosure 104 comprises an upper structure 112, which may be made from rigid struts, bars, rods, etc. In contrast to the upper structure 112 of Figure 2a, which was in the form of a rigid frame (e.g. a hoop, ring, triangular, square or polygonal frame), the upper structure 112 of Figure 8a comprises an air pocket 132. In this example, the air pocket 132 is located in the centre of the upper structure 112, and as such the upper structure 112 is in the form of a frame comprising members extending towards the centre thereof in order to support and / or define the housing of the air pocket 132. In other examples, the air pocket may be located at the side, or in the corner of, the upper structure 112. The air pocket 132 may have a rigid housing, such as an inverted receptacle, trough etc., for holding a quantity of air therein, while permitting access to the air pocket 132 from below, such as permitting access by a fish in the enclosure 104. As illustrated in Figure 8a, the air pocket 132 may be located slightly above the upper structure 112 of the fish enclosure 104. The air pocket 132 may be connected to the upper structure 112 via a rigid member, as in Figure 8a, or may be connected only via the boundary material (e.g. a net material, a perforated sheet, or the like). As such, the upper boundary of the fish enclosure 104 may be sloped, and this may assist to guide any fish towards the air pocket 132. Having an upper structure 112 that comprises an air pocket 132 may reduce the leakage of air from the air pocket by increasing its structural stability, and may provide an air pocket that experiences less motion than in known examples.

[0281] In other examples, the air pocket 132 may be defined by the boundary material (e.g. net, perforated sheet or the like) of the fish enclosure 104, for example by a portion of the boundary material that spans the frame of the upper structure 112. The air packet 132 may comprise or be defined by a reinforced and / or more tightly woven portion of the net.

[0282] Although not illustrated, the part of the upper structure 112 that extends towards the centre of the frame, e.g. to the air pocket 132, may additionally comprise a connection to a boundary material, such as a net, thereby additionally forming an upper boundary of the fish enclosure 104.

[0283] In addition, the rigid form of the upper structure 112 assists to hold the desired form of the boundary material, e.g. the net, such that fish have sufficient room to swim in the fish enclosure 104. The upper structure 112 may then be directly attached to the suspension arrangement 106 and thereby connected to the floatable structure 101 e.g. the collar 102. In Figure 8a, there is no lower structure 114 illustrated, which may be feasible in cases where the boundary material is able to hold its form under its own weight.

[0284] The upper structure 112 may additionally be used to attach equipment, such as lights, cameras, sensors etc. which may be useful for monitoring the fish enclosure 104. The upper structure may support cabling from the floatable structure 101 .

[0285] In Figure 8b, a fish enclosure 104 is illustrated having both an upper structure 112 and a lower structure 114. Here, the upper structure 112 is flexible and comprises a tensioned cable or rope, at the end of which is a connection member 112a which may permit the upper structure 112 to connect to the fish enclosure 104, e.g. to the boundary material of the fish enclosure 104, and / or the suspension arrangement 106. The tensioned cable or rope may be flexible (e.g. non-rigid). The tensioned cable or rope may be configured to deform when not under tension, e.g. when a (e.g. any) compressive force is applied thereto. In some other examples, the upper structure 112 may comprise a semi-rigid, or compliant rigid, structure, which permits a high degree of bending while still holding its shape, such as PE (polyethylene piping). While in Figure 8a, the suspension arrangement 106 is illustrated as extending substantially vertically from the floatable structure 101 towards the enclosure 104, the suspension arrangement 106 of Figure 8b extends obliquely from the floatable structure 101 , in a downwards direction from the floatable structure 101 towards the fish enclosure 104. To enable oblique extension of the suspension arrangement 106, a lateral force must be applied to the suspension arrangement 106, and as such, the suspension arrangement 106 may assist to hold the tensioned cable or rope of the upper structure 112 in tension. Such a configuration may provide a fish enclosure 104 that is less affected by underwater forces, such as currents, and may be likely to lead to slack in the suspension arrangement 106.

[0286] In Figure 9, an example of a fish enclosure 104 which may be useful in situations where there is no rigid upper structure 112, such as in the case of Figure 8b. Here the boundary material, which in this case is a net, comprises reinforced sections. The upper portion of the fish enclosure 104 is, in this example, in the form of an extruded square, or cuboid, shape, and the corners of the upper portion of the fish enclosure are comprise reinforcements 134. The reinforcements 134 may be by a denser or reinforced net material, by metal panels, by a toughened plastic, or the like. In addition to the reinforcements 134 on the corners of the net, there is also a reinforcement 134 located on the top surface (e.g. the upper boundary) of the fish enclosure 104. The reinforcement 134 may be located centrally on the top surface of the fish enclosure 104, and may comprise or define a pocket or enclosure, suitable for containing an air pocket 132. Although not illustrated, the fish enclosure 104 may comprise a lower structure 114, which may be in the form of a peripheral frame, hoop etc..

[0287] An example of an alternative suspension arrangement 106 and height adjustment means 107 is illustrated in Figure 10. In this case, the height adjustment means 107 comprises a connection member, which may be an elongate member 107, that is connected to the access structure 108. While the elongate member of the height adjustment means 107 may permit a user to raise and lower the fish enclosure 104 as needed, it may be desirable that during normal operation that the height adjustment means 107 does not bear excessive weight. Instead, the suspension arrangement 106 may be designed to bear the weight of the fish enclosure 104 under normal (e.g. daily) operation, or during height adjustment operations. Similar to the illustration of Figures 3 and 3b, the suspension arrangement 106 (e.g. comprising a cord, a cable, rope or the like) comprises a stopper 128 thereon. The suspension arrangement 106 is able to be threaded through a restrictor 126 and the stopper 128 is seated in the restrictor 126 to hold the suspension arrangement 106 in place. Here, the suspension arrangement 106 may comprise only a lower part 106b equivalent to that shown in Figure 2, and no upper part 106a. In this example, the restrictor 126 is located on a radially exterior surface (e.g. a peripherally outer surface) of the collar 102, and the suspension arrangement 106 extends at an oblique angle relative to the fish enclosure 104 and the collar (here, extending radially outwardly in an upward direction from the fish enclosure 104 to the collar 102). Having the suspension arrangement 106 extend at an oblique angle away from the fish enclosure 104 may provide a lateral stabilising force to the fish enclosure 104, giving it some degree of resistance to laterally directed forces in the water. Additionally, this configuration removes or reduces the interaction (e.g. direct contact) between the suspension arrangement 106 and the collar 102 as a result of relative movement therebetween, thereby preventing damage to either the collar 102 and / or the suspension arrangement 106.

[0288] Figure 11 illustrates an example of an air supply in the form of an air access tube 132a to permit fish in the fish enclosure 104 a protected access up to the water surface to adjust their swim bladders. The air access tube 132a may be a snorkel. The air access tube 132a extends from the upper structure 112 and above the waterline (not shown) and is connected to the floatable structure 101 (e.g. the collar 102 or access structure 108 thereof) to provide access to the air from the fish enclosure 104 and comprises an air conduit in the form of a chute, pipe, snorkel etc.. The air conduit may be impenetrable to water, and may therefore provide fish access to a supply of surface air, while providing protection from sea lice, algae and other pathogens. The air access tube 132a may therefore be partially filled with water, for example may be filled with water up to the waterline of the surrounding body of water. The air conduit may be made out of any appropriate material, such as a material impermeable to water e.g. plastic tubing, PVC fabric, tarpaulin, or the like. The air conduit may be made from one or more types of material. For example, an upper section of the air conduit may comprise a water impermeable material, while a lower section may comprise a permeable material such as net. The air access tube 132a may be connected to at least one of the access structures 108, which may provide the air access tube 132a support, and which may also provide access to the air access tube, for example for cleaning, the insertion of food therein or for monitoring purposes.

[0289] In Figure 12 there is illustrated an example of fish farming system 100 in which an access column 136 exists between the fish enclosure 104 and the floatable structure 101 (e.g. extends between the fish enclosure 104 and the collar 102). The access column may be a tube, pipe, or the like, that extends between a connection means on the floatable structure 101 (e.g. the collar 102 or the access structure 108) and the fish enclosure 104, and may be constructed from a water impermeable material. In some examples, the access column 136 may be a rigid column, while in others the column may be flexible. As illustrated, the access column 136 may extend through the upper structure 112 of the fish enclosure 104, and may extend above the water line 110. The access column 136 may be attached to the column 136 (e.g. an interior surface of the column 136) and / or a bracket located on the floatable structure 101 (e.g. the collar 102 or the access structure 108). The access column 136 may be supported by the access structure 108 and / or the collar 102, for example at a connection point or by the connection means. The access column 136 may be accessible from the access structures 108, e.g. by a vessel which may be anchored or positioned next to the fish farming system 100. Two cross-sections of the access column 136 are illustrated in Figure 12, showing the access column 136 having either a circular or a square cross-section. The skilled reader will appreciate that other shapes of cross-section are equally possible, such as a polygon, or amorphous crosssection. There may be one or several such access columns 136 to the fish enclosure 104. As illustrated in the cross-sections 136a, 136b, the access column 136 may comprise (e.g. house) a plurality of tubes and / or cables therein. For example, the access column 136 may comprise one or more of a feed hose, an air hose, a mort transport hose, a conduit for electrical and / or sensor cables, or the like therein, and / or may comprise a winch cable for holding and powering a device such as a camera, sensor device or retrieval device. The width of the access column 136 may be such that it is possible to pass objects therethrough. For example, an ROV or net cleaning robot may be passed from the surface (e.g. from the access structure 108), down the access column 136 and into the fish enclosure 104.

[0290] A further example of an access column 136 is illustrated in Figure 13a. However, in this example, the access column 136 extends through the access structure 108, which may provide further support for the access column 136 and structure 108. In addition, the access column 136 can be seen to be connected to a vessel 138, which may use the access structure 108 and access column 136 to pass cables, hoses, tubing etc. to the fish enclosure (not illustrated in Figure 13a). In one example, the access column 136 may be used to move mort from the fish enclosure 104 to a vessel. Additionally or alternatively, the access column 136 may be used to provide water circulation to the fish enclosure 104, for example from a vessel. Water circulation may be beneficial in the case where skirts are installed in the system 100, which may lead to lower oxygen levels inside the skirt. As such, the access column 136 may be used to circulate water from below the fish farm (so as not to contain lice or other contaminants) thereby providing more highly oxygenated water to the fish enclosure 104.

[0291] Figure 13b illustrates an example of a height adjustment arrangement 137 comprising a winch 135 arranged on a vessel 138, and guide sheaves 139, at least some of which are arranged on the access structure 108. As such, the winch on the vessel may be connected to the suspension arrangement 106, for example via an elongate member 106b as previously described, and used to raise or lower the fish enclosure 104 as desired. Having a winch that is located on a vessel may reduce the cost and complexity of the system 100, as it may remove the requirement to have a dedicated winch and associated sheaves.

[0292] Illustrated in Figures 14a and 14b are two examples of possible fish enclosures 104a, 104b that may be used in a fish farming system 100. In the first example, the fish enclosure 104a is made of a net material, which may be flexible, and woven / constructed in a desirable shape, such as a cylinder, cuboid, cone, pyramid, or any combination of such shapes, for example a cuboid or cylinder with a pyramid or cone or truncated pyramid or cone attached to its upper and / or lower surface. In order to hold the material of the fish enclosure 104a in the desired shape (e.g. without excessive deformation due to wave motions, currents etc.) a rigid, and possibly weighted or otherwise secured structure may be attached thereto. In this example, a rigid frame 140 (which may be a ring shape, or a square frame) is attached to the material of the fish enclosure. Although attached to a lower point of the fish enclosure 104 than in the previous Figures, the rigid frame 140 may be considered to be a lower structure 114 of the fish enclosure 104 of Figure 14a. In Figure 14a the rigid frame 140 (e.g. the lower structure 114) may be weighted so as to hold the material of the fish enclosure 104 in tension, thereby assisting the material of the fish enclosure 104 to hold a desired shape. As shown in Figure 14a, a single rigid frame 140 is attached to the bottom part of the fish enclosure, thereby holding the material above in tension. As illustrated in Figure 14a, the rigid frame 140 may be wider than the section of fish enclosure to which it is attached, which may have a stabilising effect on the fish enclosure (e.g. may provide a stabilising force against underwater currents, wave forces etc.). The rigid frame 140 may comprise a number of ties and / or struts to assist in the attachment between the rigid frame 140 and the fish enclosure 104. The ties and / or struts may be in the form of rigid members or beams, or may be in the form of ropes.

[0293] In Figure 14b, the fish enclosure 104 comprises a first and a second rigid frame 140a, 140b. The first rigid frame 140a, which may be considered to be the upper structure 112 (see figures 8a and 8b, for example), may be neutrally or positively buoyant, and therefore may produce an upwardly directed force, or no force, on the material of the fish enclosure 104. In contrast, the second rigid frame 140b, being located lower than the first rigid frame 140a, may be negatively buoyant, thereby providing a downwards force on the net material, and may be the lower structure 114. As such, the rigid frames 140a,b may assist to enable the fish enclosure 104 to maintain a desired shape. In some cases, the first and second rigid frames 140a, 140b may be identical in shape, or may differ in shape.

[0294] It should be noted that the floatable structure 101 of Figures 14a and 14b comprises only a collar 102, and in this example does not comprise an access arrangement. Here, the collar 102 may float at the surface of a body of water, and may not be fully submerged as in previous examples, or may be fully submerged but located at or adjacent the waterline (e.g. less than 1 m below the waterline). Although not illustrated, the collar may comprise a railing, frame or the like on an upper surface thereof, to permit a user to walk on an upper surface of the collar 102, which may be located above the waterline, or to walk on a walkway that is located on the upper surface of the collar 102.

[0295] In Figures 15a to 15c there is illustrated a fish farming system 100 that comprises a selectively deployable protector extending between at least two access structures 108 thereof. The selectively deployable protector may be or comprise, for example, a lice skirt 142 or a secondary net 143. In this example, the collar 102 is in the form of a square frame, and comprises an access structure 108 at each corner thereof. The selectively deployable protector (e.g. the lice skirt 142 or secondary net 143) is mounted on each side of the square frame of the collar 102, between the access structures 108, and may be considered to be one single protector, or a protector mounted on each side of the collar 102. The selectively deployable protector may be in the form of a single lice skirt 142 and / or secondary net 143 that extends around the periphery of the collar 102. In some examples, the selectively deployable protector may be the form of a plurality of lice skirts 142 and / or secondary nets 143 that together extend around the periphery of the collar 102 (e.g. the entire periphery of the collar 102). Each of the plurality of lice skirts 142 and / or secondary nets 143 may extend partially around the periphery of the collar 102. In the case where the collar 102 is circular, the selectively deployable protector may extend around the circumference (e.g. the entire circumference) of the collar 102, and may include one or a plurality of lice skirts 142 and / or secondary nets 143, as described previously. The, or each, selectively deployable protector may be configurable between a deployed and retracted configuration (e.g. may be able to be rolled up, may be foldable, may have a concertina structure, or the like) which may be controlled by a user, such that it is selectively deployable by a user. The selectively deployable protector may therefore be temporarily. The selectively deployable protector may be expandable and therefore may be considered an expandable protector. The expandable protector may be configurable between an expanded and retracted configuration. The, or each, selectively deployable protector may be mounted onto the collar 102 (e.g. an upper surface of the collar, as is illustrated in Figures 15a-c). The selectively deployable protector may also be mounted to each adjacent access structure 108, and in some examples there may be a rail or guide at the interface between the selectively deployable protector and the access structure 108 to permit translational movement, e.g. unidirectional and / or upwards / downwards movement of the selectively deployable protector relative to the access structure 108.

[0296] Although not illustrated, the protector may be configured between a deployed (and / or expanded) and retracted configuration by means of a suspension wire, configurable to raise / lower the protector, or by a cylinder (e.g. a motorised cylinder) that may be rotated so as to deploy / retract the protector. The suspension wire, roller, or the like may be operated by a device on the fish farming system 100, or may be configurable to connect to a vessel, or external object, that may be used to reel in / spool out the wire or turn the cylinder etc..

[0297] In Figure 15a there is illustrated an example of a floatable structure 101 without a lice skirt, or in which the lice skirt 142 is in the retracted configuration, and may be held in a compact form on or in the collar 102. Shown in Figure 15a is a protector in the form of a secondary protection net extending between two adjacent access structures 108. Figure 15b illustrates a fish farming system 100 in which the collar comprises a lice skirt 142 extending between two adjacent access structures 108. Here, a lice skirt 142 along one side of the collar 102 is illustrated in the expanded configuration. Fully deployed or expanded, the lice skirt 142 may extend substantially the entire vertical length between the top of the access structure 108 and a top surface of the collar 102, or in some examples may extend at least half this length. As is most visible in Figure 15c, while the collar 102 remains submerged, the lice skirt may extend upwardly from the collar 102 to a height above the waterline 110.

[0298] In Figure 15c, the fish farming system 100 is illustrated as having an expanded lice skirt 142 along each side of the square frame of the collar 102. In the example of Figure 15c, the lice skirt 142 may be expanded simultaneously along each side of the frame of the collar 102 as a single lice skirt 142, or may be deployable individually as four separate lice skirts 142, one along each side of the collar 102. The, or each, lice skirt 142 may be expanded during times where it is desirable to surface the fish enclosure e.g. bring fish in the fish enclosure 104 to the surface (e.g. waterline) of the body of water in which the fish farming system 100 is positioned, such as for harvesting or inspection of the some / all of the fish. In such cases, the fish enclosure may initially have a first, operational, position and the fish enclosure 104 may then be raised towards the waterline 110 to a second, maintenance or access, position to provide easier access to the fish therein. As the fish are brought to the surface of the water, they may become vulnerable to infestation from parasites located towards the water surface such as sea lice. By deploying the lice skirt 142 prior to raising the fish enclosure 104, sea lice and other parasites may be prevented from entering the space in the centre of the collar, where fish are accessible to be monitored, inspected and / or harvested.

[0299] In some examples, when the lice skirt is in the expanded configuration, it may be desirable to circulate the water in the fish enclosure to ensure adequate oxygenation and waste removal therein. Therefore, the fish farming system may comprise a circulation arrangement for circulating water in the fish enclosure in the maintenance position. The circulation arrangement may comprise e.g. a fluid pump or a plurality of fluid pumps, water bubblers, or the like, and may be located on the floatable structure 101 , for example the collar thereof, or may be located on or inside the fish enclosure 104.

[0300] Also illustrated in Figures 15a-c is a fish enclosure 104, the upper structure 112 of which comprises an air pocket 132, similar to that illustrated in Figure 9. Here, the fish enclosure 104 comprises upper and lower structures 112, 114 (similar to Figures 8a and 8b). An air pocket 132 is located within the upper structure 112, roughly centred with respect thereto. In this case, the upper structure 112 comprises a peripheral frame extending around enclosure boundary material (e.g. a net or mesh material), and an air pocket 132 is defined within the boundary material itself. As previously described, the air pocket 132 may be or comprise a rigid material (e.g. metal or hard plastic) and / or a flexible material (e.g. a woven material or flexible plastic).

[0301] In Figure 16, there is illustrated a protector (e.g. a lice skirt 142 or secondary net 143) in greater detail. In the example of Figure 16, the protector is in the deployed configuration. Located on (e.g. mounted, connected, bound to) the upper surface of the collar 102 is a protector base 144 (e.g. a skirt base). The base 144 may comprise a recess therein for storage of the protector when in the retracted position, and may additionally comprise a roller, in cases where the protector is stored in a rolled configuration on the collar 102.

[0302] Additionally, the collar 102 comprises a suspension line 146, and guide lines 148 for the protector. Here, a suspension line 146 extends between an upper point on one access structure 108 to an upper point of an adjacent access structure 108, along the periphery of the collar 102 of the fish farming system 100. The suspension line 146 may be located, and may be axially aligned with, each protector and base 144 in the fish farming system 100. From each suspension line 146 extends a plurality of guide lines 148 - in this example three. While the suspension line 146 may extend in a horizontal arc between the access structures 108, the guide lines 148 extend vertically between the suspension line 146 and the base 144, and may be attached to both the suspension line 146 and the base 144. The guide lines 148 may be attached to the protector so as to permit upwards and downwards translational movement of the protector relative to the collar 102 and access structures 108, but restrict other movement. The guide lines 148 may be threaded through the skirt 142, or may attach to the skirt by a plurality of hoops, hooks etc..

[0303] Figures 17a and b illustrate alternative examples of a protector. In the examples shown, the protector is in the form of a lice skirt 142. In the illustrated examples, the protector extends below the waterline when the fish farming system 100 is positioned in a body of water. In Figure 17a, the skirt 142 extends to a depth below the waterline so as to enclose both the upper and lower structures 112, 114 when the fish enclosure 104 is in a raised position relative to the floatable structure 101. In some examples, the skirt 142 may extend to a level between the top and bottom of the fish enclosure 104 (e.g. between the upper and lower structures 112, 114). In Figure 17b, the fish enclosure 104 is in a lowered position relative to the floatable structure 101. In Figure 17b, and example of a skirt 142 is illustrated in which the width of the skirt 142 (or diameter, in the case of a circular collar 102) relative to the floatable structure 101 varies, and the skirt is positioned both above and below the collar 102 (e.g. extending between two adjacent access structures). As such, there may be considered to be two lice skirts - an upper and a lower lice skirt, where the upper lice skirt is partially submerged and the lower lice skirt is fully submerged. In this example, the portion of the skirt extending between the two access structures 108 above the collar (e.g. the upper lice skirt) is narrower than the portion of the skirt extending below the collar 102 (e.g. the lower lice skirt). For example, the skirt 142 above the collar 102 may have a width equal to an internal diameter or width of the collar 102, whereas the skirt 142 below the collar may have a width equal to an outer diameter or width of the collar 102.

[0304] Figures 18 and 19 illustrate steps involved in the installation and subsequent removal of a fish farming system 100 from an offshore location. In Figure 18, the fish farming system 100 is illustrated mounted on a vessel 150. Once near the installation site, the fish farming system 100 may be supported by a crane 152, or other lifting apparatus, on the vessel 150, and may then be lifted into a desired position. Figure 18 illustrates a single fish farming system 100 both mounted on a vessel 150 and then as positioned in an offshore location. In another example, which may be preferable in some cases, the fish farming system 100 may be positioned on a quay, before being sea-launched by a crane 152 and towed to an installation site. While being towed, the buoyancy of the fish farming system 100 may be configured to be buoyant, such that the collar 102 floats in the surface of the water during towing.

[0305] During transportation and initial positioning of the fish farming system 100, the fish enclosure 104 may be in a collapsed configuration, in which the boundary material is held together (e.g. folded or rolled together) about a rigid frame 140 or rigid frames 140a, 140b (see Figures 14a and 14b), of the upper and / or lower structures 112, 114 of the fish enclosure 104. In the case where the fish farming system 100 comprises both an upper and a lower structure 112, 114, the structures may be held together by a tie 154 during transport. The tie 154 may enable the fish farming system 100 to be transported stably, and may then be undone, removed or severed once the fish farming system 100 is positioned in an offshore location, and it is to be installed. Although not shown in Figure 18, a suspension arrangement connects the fish enclosure 104 to the collar 102.

[0306] Once the tie 154 has been removed, undone, severed etc. then the suspension arrangement 106 may be used to lower the fish enclosure 104 to the position as shown in Step 1 of Figure 19. In Step 1 of Figure 19, the fish farming system 100 may be substantially similar to that as described in Figure 2a, and may be ready for normal operation.

[0307] Steps 2 to 6 of Figure 19 illustrate the steps involved in one method for removal of fish from the fish enclosure 104 of the fish farming system 100. Illustrated in Step 2, the suspension arrangement 106 may be used to raise the fish enclosure 104 from a lowered position to a raised position. To do so, a winch, or winch arrangement, may be used to shorten the length of the cabling, wire, rope etc. of the suspension arrangement 106. In the raised position, a top portion of the fish enclosure 104 may be located above the collar 102, and at or slightly below the waterline 110.

[0308] Once in the raised position, the fish enclosure may be further raised above the waterline 110 (e.g. by a secondary lifting mechanism such as a rack-and-pinion mechanism attached to the access structure, or by further shortening of the suspension arrangement 106) to begin to reduce the available volume to fish in the fish enclosure, as shown in Step 3, and part thereof may be secured to the access structure 108, which in this example is in the form of vertical columns. The fish enclosure 104 may be further raised through use of a vessel (not shown) such as a crane or winch arrangement on a vessel. In the case where the fish enclosure 104 comprises an upper and a lower structure 112, 114 (such as illustrated in Figure 8b), the first frame 140a may be secured to the access structure 108 - as shown, in this example the top of the access structure.

[0309] Once part of the fish enclosure 104 has been secured to the access structure 108, then the remainder of the fish enclosure 104 (e.g. the lower parts of the fish enclosure) may be raised and held together with the secured part of the fish enclosure 104. In some examples, at least a part of the netting of the fish enclosure may be folded or rolled together as the parts thereof are raised and held together, as is illustrated in Step 4. In cases where there is an upper and a lower structure 112, 114, the upper and lower structure 112, 114 may, at this point, be brought together, and held together by means of a tie 154 as was previously illustrated in Figure 18. As the upper and lower structures 112, 114 are brought above the waterline, the fish in the fish enclosure may be restricted to a relatively small volume within the net.

[0310] In this example, and in some previous examples, the fish enclosure 104 comprises a lower section which may be in the form of an inverted cone or pyramid, and which may comprise a weight at the apex thereof, in order to hold the material of the fish enclosure 104 in tension. In such cases, the inverted cone or pyramid may be again inverted, or at least partially inverted (as illustrated in Step 5 of Figure 19) so as to assist to provide a more compact arrangement of the fish farming system 100 for removal of the fish therein, by forcing the fish to the surface where they may be removed by a removal device, such as a grabbing and / or suction device. As illustrated in Steps 5 and 6 of Figure 19, once the inverted cone or pyramid has been again, at least partially, inverted, the entire, or almost the entire fish enclosure 104 may be above the level of the collar 102, or at least above the level of the lower surface of the collar, and therefore the available volume to the fish in the fish enclosure is at a minimum, allowing for ease of extraction of fish therein.

[0311] In some examples, such as that shown in Figure 19, the collar may comprise a ballasting arrangement. The ballasting arrangement may be in the form of a plurality of ballast tanks, which may be located inside the collar 102 and / or access structure 108. In step 6, the water may have been released (e.g. pumped) from the ballast arrangement so as to reduce the weight of the fish farming system 100, thereby reducing its draft. This position ensures the nets are lifted above water to extract the last remaining fish.

[0312] Figure 20 illustrates the opening of the fish enclosure 104, where the fish enclosure 104 comprises a lower structure 114 and may comprise an upper structure 112 which may have a rigid peripheral frame 140a, or which may simply comprise an air pocket 132, which may have a rigid housing, or a flexible housing such as a woven housing. As previously indicated, the lower structure 114 may be weighted in order to hold the boundary material of the fish enclosure 104. In this example, the fish enclosure 104 is generally in the form of a cuboid, and comprises an inverted pyramid forming the bottom thereof, although other shapes of fish enclosure 104 are also possible, as has previously been described. Here, the lower structure 114 comprises a rigid frame 140b.

[0313] The upper part of the fish enclosure 104 comprises an air pocket 132, the buoyancy of which may provide an upward force and may assist to hold tension in the material (e.g. net) of the fish enclosure 104 in tension. As illustrated in Step 1 of Figure 20, the upward force caused by the air pocket 132 may urge the upper surface of the fish enclosure 104 naturally into a truncated pyramid shape.

[0314] Illustrated in Step 2, the fish enclosure is raised, similar to as described in Figure 19. Once the air pocket 132 reaches the waterline 110, upwards movement with the fish enclosure 104 is no longer possible, and the air pocket structure 132 simply floats at the waterline 110, causing the upper structure of the fish enclosure 104 to lose some tension.

[0315] In order to maintain access to the fish enclosure, an enclosure support arrangement 152 may be installed or attached to the fish farming system 100. In the example of Figure 20, the support arrangement comprises a plurality of cranes, each access structure 108 comprising or being connected to one crane. Each crane comprises a line (e.g. a wire, a cable, a rope etc.) which may be connected to the air pocket structure 132, or to the upper surface of the fish enclosure 104, in order to provide access to the air pocket 132 and / or the upper surface of the fish enclosure 104 higher than the waterline, as illustrated in Step 3 of Figure 20. Although cranes mounted on the floatable structure 101 are illustrated in this example, the support arrangement 152 may equally be in the form of cranes, winches, davits, or the like, mounted on a vessel. The provided user access may permit a user to open the fish enclosure (e.g. by unfastening an opening) to thereby remove fish from the fish enclosure 104. Alternatively or additionally, the support arrangement 152 may be used to provide access to the fish enclosure for the purpose of providing a net replacement.

[0316] Figures 21a and 21 b illustrate an example of an air pocket structure 132 in further detail. As previously described, the air pocket structure 132 may be relied upon to provide tension in the material of the fish enclosure 104. As such, the air pocket structure 132 may be designed for optimal stability, thereby providing a reliable degree of tension to the fish enclosure 104 (e.g. the boundary material of the fish enclosure).

[0317] To increase the stability of the air pocket structure 132, and also the buoyancy thereof, a buoyancy element, or buoyancy elements 156 may be affixed thereto. The buoyancy elements may be attached to the air pocket structure 132 around the periphery thereof (as shown in Figure 21 a) and / or may be attached to an upper surface thereof (as shown in Figure 21b). Not only may the buoyancy elements 156 increase the buoyancy of the air pocket structure 132, but also the stability. For example, the buoyancy elements 156 may assist to prevent the air pocket structure from tipping or flipping over, thereby releasing air contained therein. In this example, the buoyancy element 156 is used in combination with an air pocket that may be defined by the boundary material, and additionally or alternatively that may be connected to an upper structure via the boundary material.

[0318] An additional measure that may be taken to increase the stability of the air pocket structure 132 is the attachment or integration of weights to a lower part thereof. Figure 18b illustrates weights 162 attached to the lower periphery of the air pocket structure 132. Similar to the buoyancy element(s) 156, the weights may assist to prevent the air pocket structure 132 from tipping or flipping.

[0319] In Figure 21b, there is illustrated an air vent 158 located in an upper surface of the air pocket structure 132. The air vent 158 may be used to add or remove air from the air pocket structure 132 (e.g. via an air hose), and may be used to selectively vary the water level 160 inside the air pocket. While a lower water level 160 may provide more air for fish in the enclosure 104, a higher water level 160 may provide more stability to the air pocket 132. Having weights 162 and / or buoyancy elements 156 may therefore permit a lower water level 160 to be viable, therefore permitting the fish in the fish enclosure 104 access to a larger volume of air.

[0320] Figures 22a-e illustrate alternative examples of floatable structures 101 that a fish farming system 100 may comprise. In Figures 22a and 22b, the collar 102 of the floatable structure 101 has a square or rectangular shape (e.g. a square or rectangular horizontal cross-section), while in Figures 22c-e the floatable structure 101 has a collar with an octagonal shape. Further, in Figure 22b, the floatable structure 101 defines a plurality of collars, each defining an access opening therein. In the example of Figure 22b the floatable structure 101 defines two collars 102a, 102b, whereas in Figure 22d the floatable structure 101 defines four collars 102a-d. In examples where the floatable structure 101 defines a plurality of collars 102, adjacent collars may comprise a common edge, as is illustrated in Figures 22b and 22d. In Figures 22a and 22b, the collars 102, 102a, 102b comprise an access structure 108 at each vertex thereof. In the example of Figure 22c, some vertices of the collar 102 are absent an access structure 108, while an access structure 108 is present at a midpoint of an edge (e.g. a side) of the collar 102.

[0321] In the example of Figure 22d, the floatable structure 101 comprises four collars 102a- d, each of which have an octagonal shape. As previously described, each adjacent collars 102a-d are arranged such that adjacent collars 102a-d share an edge. In this example, the floatable collars 102a-d are rotationally symmetrical about a vertical axis of the floatable structure 101. As illustrated in Figure 22d, the plurality of collars 102a- d are arranged so as to define a secondary access opening 170 in the floatable structure 101. The secondary recess 170 is enclosed within each of the collars 102a- d of the floatable structure 101 . In this example, the secondary recess 170 comprises a storage container. In Figure 22e, there is illustrated a cross-sectional view along section A-A of Figure 22d. Figure 22e illustrates the secondary recess 170 and the storage container contained therein in more detail. The storage container extends below the waterline in this example, when the floatable structure 101 is located in a body of water, and may be used to store equipment such as conduits, hoses, nets, feed or the like.

[0322] Further illustrated are fish enclosures 104a, 104b. Although only two fish enclosures 104a,b are illustrated, a fish enclosure 104 may extend from each of the collars 102a- d of the floatable structure 101 of Figures 22d and 22e, and any other examples where the floatable structure 101 comprises a plurality of collars 102. The suspension arrangement 106 of the example of Figures 22d and 22e extends between each vertex of each collar 102a-d and the fish enclosure (e.g. an upper structure 112 of the fish enclosure). In this example, the each fish enclosure 104a,b comprises an octagonal horizontal cross-section, in common with the cross-section of the collars 102a-d. However, it should be noted that the horizontal cross-section of the fish enclosures 104a,b need not be identical to the horizontal cross-section of the collars 102a-d, and may be circular or square, for example.

[0323] Figures 22a-d illustrate some of the steps involved in removing the fish farming system 100 from its location in a body of water, focussing on the movement of the material of the fish enclosure 104, which in this case is a mesh net.

[0324] Illustrated in Figure 23a is an example of a fish farming system 100 having a fish enclosure 104 suspended from the collar 102 via a suspension arrangement 106. Here, fish enclosure 104 has a cuboid shape (with an inverted pyramid forming the base surface thereof, as in previous examples). The fish enclosure 104 comprises an upper rigid frame 140a and a lower rigid frame 140b, with the suspension arrangement 106 comprising four lines, with each line connecting to a corner of both the upper and lower frames 140a, 140b. Here, the upper rigid frame 140a is slightly larger (e.g. wider, with a greater diameter, or the like) than the lower rigid frame 140b (for example, the upper rigid frame 140a may be 40m by 40m, while the lower may be 35m by 35m in dimension). As such, and as is clearly illustrated in Figures 23b and 23c, the mesh net of the fish enclosure 104 hangs vertically down from the upper structure 112, and must also be horizontally displaced to account for the smaller lower structure 114. In this example, the mesh net is attached to both the upper and lower structures 112, 114, and has a length slightly longer than the vertical distance between the upper and lower structures 112, 114. The length of the mesh net, combined with the lower structure 114 being smaller than the upper structure 112, has the effect of causing a lower portion of the mesh net to hang in a U-bend (best seen in Figs 23b-d), thereby extending upwardly and radially inwardly from the bottom of the U-bend to connect to the lower structure 114.

[0325] Figure 23d illustrates the mesh net in the instance where the lower structure 114 has been raised, for example by the suspension arrangement 106, for example because it is desired to empty the cage of fish farming system 100, as described in relation to Figures 19 and 20. Having a U-bend may be advantageous, because it conveniently provides a stable structure for the mesh net when the lower structure 114 of the fish enclosure is being raised. In this way, the lower structure 114 may be easily raised and lowered without worry that the mesh net may become damaged.

[0326] Figures 24a and 24b illustrate guards 164 that may be present on the lower structure 114. In Figure 24a, the guard 164 is in the form of a continuous sheet, extending outwardly and upwardly from the lower structure 114, before curving back in towards the lower structure 114. The guard 164 may therefore be considered substantially J- shaped, and / or hook-shaped. The guard 164 may function to hold the mesh net of the enclosure 104 away from the lower structure 114, thereby enabling a smooth transition into the U-bend, with reduced risk of catching on the lower structure 114. In addition, the guard may prevent fish from swimming into the U-bend section of the fish enclosure 104, which could result in injury or death.

[0327] Figure 24b illustrates a different guard 164 comprising a plurality of rods, having a similar cross-sectional shape to the guard of Figure 24a (e.g. a J-shape). Here, the rods may be positioned sufficiently close together or with netting between so as to prevent a fish from passing.

[0328] In addition, Figure 24b illustrates the material of the fish enclosure 104 (e.g. the mesh net) at the corner of the lower structure 114. Here, the guard 164 may effectively increase the radius of curvature of the corner of the lower structure 114, thereby permitting the material of the fish enclosure 104 to also have a larger radius of curvature at the corner thereof, permitting a smoother curving at this section, and reducing the likelihood of wrinkling or damage at this section.

[0329] The material of the fish enclosure 104, which may be in the form of a net, may be made from any appropriate material, such as a metal or a polymeric material or natural fibres. In some examples, the material may be made from or comprise copper or a copper alloy. Some possible materials for the net may be nylon, dyneema, HDPE, PET, or a combination of the aforementioned, for example a combination of these materials at different locations. The material of the net may be selected based on the design of the fish enclosure 104. For example, where the net is required to have a negative buoyancy (such as in Figures 24a and 24b), the material of the net may be a copper alloy, for example. Where the net is not required to have a negative buoyancy (e.g. because the enclosure 104 comprises a weighted lower structure that will hold the net in tension, such as in Figure 2) then the net material may be a polymer, for example. Such a material may be sufficiently strong to provide a net to enclose fish therein, while also providing some degree of flexibility and / or ductility to facilitate some bending of the material (e.g. net) as previously described. The copper or copper alloy may be particularly resistant to corrosion, which may be a particularly relevant factor in the case of a fish farming system 100, as the water in the fish farming system 100 may be more acidic than would normally be expected in any given offshore location.

[0330] Illustrated in Figures 25a-c is an example of a guide arrangement 182. A floatable structure 101 may comprise one or more guide arrangements 182, which may be used to guide a fish enclosure 104 away from the floatable structure 101 (e.g. the collar 102 of the floatable structure 101), thereby reducing the likelihood of damage caused by contact between the floatable structure 101 and the fish enclosure 104. For example, as the fish enclosure 104 is raised and lowered relative to the floatable structure 101 (see Figure 19, for example), there may be a risk of collision between the collar 102 and the upper and / or lower structures 112, 114 of the fish enclosure 104. To reduce the risk of a collision, or avoid significant damage occurring to either the fish enclosure 104 or the floatable structure 101 , a guide arrangement 182 may be positioned on the floatable structure 101 in locations that are known or expected to pose a risk of collision with the fish enclosure 104.

[0331] As illustrated in Figures 25a-c, the guide arrangement 182 is positioned on the collar 102, in this example the collar 102 may be a square, rectangular, polygonal etc. shape, and the guide arrangement 182 may be positioned at a vertex of the collar 102. Also located at the vertex of the collar 102 is an access structure 108. In this example, the guide arrangement 180 is positioned on both an upper and lower surface of the collar 102 and comprises a plurality of guide lips 184 configured to guide the fish enclosure 104 (e.g. an upper / lower structure, or a net, of the fish enclosure) away from the collar 102, and towards the recess defined by the collar 102, thereby avoiding or reducing any impact between the collar 102 and the fish enclosure 104.

[0332] Here, the access structure 108 is intersected by the collar 102 at a point of contact, or a point of intersection between the collar 102 and the access structure 108. The guide arrangement 182 is positioned on the upper surface of the collar 102, at an interior edge thereof (e.g. an edge of the interior facing surface of the collar 102), such that a base of each of the guide lips 184 of the guiding arrangement 182 is aligned with the interior edge of the collar 102. Each of the guide lips 184 extend upwardly and outwardly (e.g. laterally outwardly from the centre of the collar) from the base on the upper surface of the collar 102. As illustrated in Figure 25a, the guide lips 184 may additionally extend upwardly along an access structure 108, where there is an access structure positioned near or at the guiding arrangement 182 to form a funnel configuration. As such, the shape of the guide lips may guide the fish enclosure 104, or a part thereof, away from the collar 102 and towards the recess defined by the collar 102 during downward motion, thereby avoiding any potential collisions.

[0333] Illustrated both in Figure 25a and 25b, the guiding arrangement 182 may additionally extend downwardly and laterally outwardly from the collar 102. As such, the guiding arrangement 182 may comprise a second set of guide lips 186, having a base on the lower surface of the collar 102 and aligned with an interior (e.g. an interior facing) surface of the collar 102. As such, the guiding arrangement 182 may assist to guide the fish enclosure 104, or a part thereof, away from the collar 102 also during upward motion.

[0334] The guiding arrangement 182 may extend along a bottom surface of the collar 102 (e.g. an underside of the collar). In such examples the guiding arrangement 182 may connect to a restrictor 126 (see Figure 10, for example) that is located on an outward (e.g. outwardly facing) surface of the collar 102. As such, the guiding arrangement may additionally be used to provide structural support to the restrictor 126.

[0335] The guiding arrangement 182 and the guide lips 184 may also serve a secondary purpose as an improved and fatigue friendly structural connection between access structure 108 and collar 102.

[0336] The present disclosure also provides an improved fish farming structure for closed fish farm. According to an example embodiment there is provided a fish farming structure for a closed fish farm, comprising: a floatable structure comprising a collar and an access structure; a closed fish enclosure configurable to be suspended from the floatable structure via a suspension arrangement; the collar defining an access opening therein for providing access to the fish enclosure, and the collar being configurable to be submerged in a body of water; the access structure located on the collar, and being configurable to extend from a submerged location at which the access structure connects to the collar to a location above a waterline of a body of water; the closed fish enclosure being configurable to extend above the level of the collar.

[0337] In use, the fish farming structure may be placed in an open-water location and the closed fish enclosure suspended from the floatable structure. The collar of the floatable structure being submerged in a body of water may have a protective effect on the floatable structure and closed fish enclosure suspended therefrom, by limiting the effect of environmental forces such as surface waves on the collar, and thereby having a reduced effect on the movement of the floatable structure and fish enclosure therein. In protecting the fish enclosure from the effect of environmental forces, more flexibility may be afforded to the design on the closed fish enclosure by permitting a design in which less priority is required to be given to durability of the material of the closed fish enclosure. For example, it may be desirable for the fish enclosure to be made from a deformable material without incurring excessive cost.

[0338] In Figure 26, there is illustrated an example of a fish farming system 200 according to the present disclosure, shown in cross-sectional elevation. In this example, the fish farming system 200 comprises a floatable structure 201 , which in this example is a semi-submersible structure (e.g. comprising a submerged portion, and a nonsubmerged portion), although in other examples may float on the surface. The fish farming system 200 of this example may therefore be considered to be a semisubmersible fish farming system.

[0339] According to this disclosure and as is understood in the art, a traditional open fish farm is one comprising an enclosure having a net, cage or similar open barrier material which is positioned in a body of water either wholly or partially below the waterline, and which functions as a barrier to prevent fish from passing therethrough and outside of the enclosure, and to prevent predators from entering the enclosure and causing a danger to the fish inside, but is but is not intended to prevent the flow of water therethrough, as well as and suspended particulate matter and microorganisms therein.

[0340] The term “closed fish farm” is also understood in the art, and refers to a fish enclosure having a net, cage or similar barrier material that provides an enhanced barrier compared to that of an open fish enclosure, in that it prevents fish and predators from passing therethrough, as well as acting as a barrier to other organisms or matter. Many types of closed fish farm exist, and may be considered to be semi-closed or fully-closed. Herein the term “closed fish farm”, “closed fish enclosure” or similar should be taken to encompass both a fully-closed and a semi-closed fish farm or enclosure unless specified or described otherwise.

[0341] A fully-closed fish farm is herein intended, as is understood in the art, to describe a farm comprising an enclosure that prevents the passage of all matter therethrough (e.g. water, detritus, parasites, pathogens, marine organisms), with the exclusion of any inlets, outlets or openings (e.g. the opening at the top of the fish enclosure) that may also form part of the fish enclosure and may be intended to permit fluids and suspended particulate matter through the barrier of the closed fish enclosure, thereby completely separating the fluid volume inside the fully-closed fish enclosure from the surrounding body of water. A fully-closed fish farm may therefore comprise an enclosure that is water impermeable. The inflow or outflow of fluids from a fully-closed fish farm may be completely controlled by a user, for example by the opening and closing of fluid inlets and outlets to the fish enclosure. The fully-closed fish enclosure may be or comprise a sheet or collection of connected sheets of water impermeable material, which may be a flexible fabric material, a rigid sheet of metal, or the like.

[0342] A semi-closed fish farm is herein intended to describe fish farm comprising an enclosure that provides an enhanced barrier compared to that of an “open” fish enclosure, in that it prevents not only the passage of predators and fish through the walls of the enclosure, but also other matter and organisms (e.g. microorganisms), which may include some or all of particles of fish feed, fish waste such as faeces, sea lice, marine parasites, algae, plankton, or the like, but may permit the passage of seawater and other fluids therethrough. A semi-closed material may therefore be water permeable, and may be or comprise a sheet of water permeable fabric, a finely woven net, a rigid metal sheet with perforations (e.g. pinhole perforations) therein, or a combination of such materials. In some examples, a semi-closed fish enclosure may comprise both a section that is water impermeable and a section that is water permeable. A semi-closed enclosure may be made from a combination of materials that are selected in order to provide the desired enhanced barrier. For example, a semi-closed enclosure that is desired to provide a barrier to sea lice, algae, pathogens, or the like that are found near the water surface may comprise an upper section of water-impermeable material, and a lower section of water permeable material (which may even be a standard net material in some examples), thereby permitting the passage of water into the fish enclosure, but preventing the passage of e.g. sea lice into the enclosure, which reside near the water surface.

[0343] A closed fish enclosure may be considered to be one in which the fish enclosure comprises a controlled interface in the form of a physical barrier to the surrounding body of water, to prevent the entry of marine organisms such as marine invertebrates e.g. sea lice, plankton, jellyfish, algae, pathogens, detritus or the like, and also to contain fish waste particles and uneaten fish feed, such that it can be released from the closed enclosure in a controlled manner. In contrast to conventional fish enclosures which comprise a net or cage as means to contain fish therein and to exclude predators, a closed fish enclosure comprises additional control at the boundary between the fish enclosure and the surrounding body of water, so as to additionally restrict passage of e.g. feed and waste therethrough, which may be removed from the fish farm in a controlled manner by a user (e.g. by pumping water out of the fish enclosure, opening a fluid outlet in the enclosure, or the like) and / or parasites, pathogens, algae, or the like as previously described.

[0344] The floatable structure 201 comprises a collar 202 and an access structure 208 located on the collar, and in this example from which a fish enclosure 204 is suspended via a suspension arrangement 206. The fish enclosure 204 comprises a plurality of connection points via which the suspension arrangement 206 is able to connect to the floatable structure 201 (e.g. the access structure 206 of the floatable structure 201). The collar 202 may be a buoyant collar and / or the access structure 208 may be a buoyant access structure 208.

[0345] Unless otherwise stated, the term “buoyant” should be understood to mean positively buoyant.

[0346] Suspending the closed fish enclosure 204 via a suspension arrangement 206 may assist to keep the closed fish enclosure at a desired elevation with respect to the floatable structure 201 , and may offer a degree of damping of the transfer of movement between the closed fish enclosure 204 and the floatable structure 201 , for example as a result of environmental forces acting upon the floatable structure 201 .

[0347] Having a closed fish enclosure may offer many benefits. For example, algae, pathogens and lice that thrive near the water surface, for example due to access to sunlight and oxygen and because of proteins and fats that are more abundant at the water surface, may be prevented access to the closed fish enclosure 204, and therefore the fish enclosure 204 may act as a physical barrier. As illustrated, the fish enclosure 204 extends such that a portion thereof (e.g. at least a portion thereof) is located above the collar 202, and in this example above a waterline 205. The closed fish enclosure 204 may therefore be able to enclose a volume of fish and water therein, without risk of the fish escaping from the fish enclosure 204. Explained in further detail in the following paragraphs, the closed fish enclosure may comprise a roof enclosure, which may partially or fully cover an upper or top opening in the fish enclosure 204. The roof enclosure may serve both to protect fish inside the fish enclosure 204 from surface dangers such as aerial predators, and may also serve to prevent fish from escaping from the enclosure 204.

[0348] Although not illustrated in this example, mooring lines may be connected to the floatable structure 201 (e.g. to the collar 202 or the access structure 208) to hold the floatable structure 201 in a desired location. The mooring lines may be arranged in a frame mooring or an independent mooring system.

[0349] In some examples, the floatable structure 201 (e.g. the collar 202 and / or the access structure 208) may comprise at least one buoyancy member as part of the structure or connected thereto, for example tied or bolted thereto. In some examples, the floatable structure 201 (e.g. the collar 202 and or the access structure 208) may comprise a plurality of buoyancy members connected thereto, for example two, three, four or more buoyancy members. The at least one buoyancy member may be in the form of a closed void or air-filled compartment which may be in the form of a tank comprising an opening (optionally with a valve located therein) for permitting entry and exit of a fluid (e.g. water) therefrom. Additionally or alternatively, the at least one buoyancy member may comprise a buoyant material, such as a buoyant foam or cellular material. In some examples, the entire collar 202 may be considered to be a floater. For example, the collar may be hollow or comprise a cavity therein providing buoyancy to the collar 202, and that is able to be filled and emptied of air and / or water if desired, e.g. the collar 202 may be able to be ballasted (as will be described in further detail in the following paragraphs). In some examples, the buoyancy of the floatable structure may be provided entirely or partially by the access structure 208.

[0350] The collar may comprise perforations (e.g. apertures, slots, or the like) therein, or comprise one or more perforated portions, for example the collar 202 may comprise a portion thereof that comprises a grate or truss structure. Having one or more perforated portions may permit water to flow through the collar 202, thereby reducing the impact of water currents and waves on the collar, and permitting self-adjustment of the buoyancy of the collar 202 by permitting water to flow into and from the collar as it rises above and falls below the waterline (e.g. flow under the force of gravity or a differential in relative density between, air and water).

[0351] The floatable structure 201 (e.g. the collar 202 of the floatable structure 201 ) may be rigid. Having a rigid floatable structure 201 may greatly reduce or remove the deformations of the floatable structure 201 as a result of wave motion. Reducing the deformations of the floatable structure 201 may similarly reduce deformations and load concentrations on an attached fish enclosure, thereby having a protective effect on the fish enclosure (as compared to an example in which the floatable structure was flexible, for example).

[0352] In this example, the access structure 208 extends above a waterline 205, while the collar 202 is fully submerged (i.e. substantially all the collar 202 is located below the waterline). The floatable structure 201 therefore comprises a submerged portion (the collar 202 and a lower section of the access structure 208) and a non-submerged portion above the waterline (an upper section of the access structure 208) and therefore the floatable structure 201 can be considered to be a semi-submersible structure. As is illustrated, the collar 202 is completely submerged, and in some examples at least part of the collar 202 may be configurable to be located above the waterline, for example at least temporarily (such as during maintenance and inspection of the collar 202). In some examples, the floatable structure 201 may float on the waterline, and neither the access structure 208 nor the collar 202 may be fully submerged. In such examples, the floatable structure may not be considered semisubmersible, and may be considered a surface-floatable structure, wherein the collar 202 floats on the surface of the body of water. The floatable structure 201 may be configurable between a submerged and a non-submerged configuration. The submerged configuration may be an operational draft of the floatable structure 201 , while the non-submerged configuration may be considered to be a temporary or maintenance draft of the floatable structure 201 . The floatable structure 201 may be configurable between a first and a second draft, which may be the operational draft and maintenance draft.

[0353] In one example, an upper surface of the collar 202 may typically be located 3 metres below the waterline 205, while a lower surface of the collar 202 may typically be located 6 to 9 metres below the waterline 205. This should be considered one example embodiment; other embodiments could be significantly deeper or significantly shallower. The actual depth of the upper and lower surfaces of the collar may vary depending on the size of the cage, the expected environmental conditions, and the desired hydrodynamic properties of the floatable structure 201 . As the access structure 208 extends above the waterline, a user may be able to use this structure to locate the fish farm 200 and also to access another part of the fish farm 200 (e.g. via a communication line, winch etc.). In some examples, such as those described in the following paragraphs, a user may be able to mount or board the part of the access structure 208 that extends above the waterline. For example, a user may be able to board / mount the access structure 208 to facilitate access to another party of the fish farm 200 (e.g. an enclosure or apparatus thereof). Additionally, having the collar 202 completely submerged may reduce the magnitude of forces acting on the suspension arrangement 206 due to external forces, such as wave motion. The reduced water plane area from access structures 208 compared to the collar 202 will change the motion response of the floatable structure 201 . For example, motion of the submerged collar 202 may be reduced (and may also be damped) compared to that of a collar that floats on the surface, for example because forces from wave motion on the floatable structure 201 diminish with depth, and will therefore be lesser on submerged parts of the structure.

[0354] Further, the floatable structure 201 may comprise a self-ballasting arrangement, for example comprising at least one self-ballasting structure (e.g. in the form of a container or tank) with openings therein which will be filled with water when submerged. The self-ballasting structure may be in the form of a soft tank. The selfballasting structure may be or comprise an open cavity, compartment or the like that is able to be filled with water via an aperture therein, once the self-ballasting structure is submerged below a waterline. The at least one self-ballasting structure may be located on the collar 202 or the access structure 208, and in some examples there may be a plurality of self-ballasting structures. In such examples, having the collar 202 at a submerged location will effectively increase the mass of the floatable structure 201 by permitting the self-ballasting structures to fill with water, and therefore increase the inertia of the floatable structure 201 and reduce excitation and sudden movements of the floatable structure 201 , for example caused by wave motion. This may be achieved without the need to pump fluid, as the tank will ballast naturally with a flow of water through an aperture, e.g. an open aperture. As such, having the collar submerged 202 may reduce sudden and / or jarring forces (snap loads) on the suspension arrangement 206, thereby prolonging the life of the suspension arrangement 206 and reducing the risk of sudden failure thereof.

[0355] The at least one self-ballasting structure may have an opening, or the openings, thereof blocked by a user, thereby permitting a user to choose whether the selfballasting structures should be free to fill and empty as they are submerged, or whether the self-ballasting structures should have a fixed buoyancy. A user may therefore be able to use the self-ballasting structures to vary key properties (e.g. structural properties) of the floatable structure 201 to achieve optimised hydrodynamic and stability properties that are tailored to the requirements of the fish farming system. Further, the user may minimise the required energy to change draft of the structure.

[0356] The access structure 208 may be buoyant. For example, the access structure 208 may comprise at least one buoyancy member, and / or floater as described above in reference to the collar 202. In some examples, the access structure 208 may be configurable to be buoyant, thereby providing buoyancy to the floatable structure 201 . In such examples, the access structure 208 may have positive buoyancy, while the collar 202 has a positive, neutral or negative buoyancy. The access structure 208 may provide substantially all of the positive buoyancy of the floatable structure 208, or may provide a majority of the positive buoyancy of the floatable structure.

[0357] In the example of Figure 26, the access structure 208 is in the form of (one or) a plurality of columns (e.g. pillars, cylinders, or the like) extending upwardly from the collar 202. At least one, or each, of the plurality of columns may extend vertically upwardly from the collar 202, or may extend upwardly at an oblique angle to the collar 202 (e.g. relative to an upper surface, or to a circumferentially or peripherally extending axis through the centre of the collar structure). The plurality of columns of the access structure 208 may be equidistantly spaced around the collar, or may be located in a plurality of groupings of two or more columns (where the columns in each grouping are adjacently located).

[0358] In some examples, the columns of the access structure 208 may extend both above and below the collar 202, which may be provide benefits in ease of structural design or fabrication.

[0359] In having a semi-submersible fish farming system 200 as described above the area of the fish farming system 200 that intersects the waterline 205 (e.g. the water plane area) may be reduced. In some examples, only the access structure 208, which may comprise a plurality of vertically and / or obliquely oriented columns, intersects the waterline, thereby reducing the water plane area as compared to examples in which the entire collar 202 intersects the waterline. Reducing the water plane area will change the response of the floatable structure 201 in waves and reduce wave loads. For example, hydrodynamic response (natural period) in heave is governed by relationship between water plane area and total mass. For a closed system, the mass will include the entrapped water in the fish enclosure 204. With a large water plane area, the hydrodynamic mass forces on the interface between the collar and the bag (e.g. acting on and / or through the suspension arrangement 206) will be very large compared to a floatable structure 201 with small water plane area, as stiffness and mass forces are out of phase. As such, having a semi-submersible fish farming system 200 as is described will reduce the loads on the fish enclosure as a result of, for example, wave loads acting on the floatable structure 201 .

[0360] The fish enclosure 204 is connected to the floatable structure 201 . The fish enclosure 204 is connected to the floatable structure 201 via suspension arrangement 206. The suspension arrangement 206 extends between the floatable structure 201 and the fish enclosure 204. Here, the suspension arrangement 206 extends between a plurality of the access structures 208 and the fish enclosure 204, although in some other examples, the suspension arrangement 206 may additionally or alternatively extend between the collar 202 and the fish enclosure 204.

[0361] The suspension arrangement 206 comprises at least one elongate member in this example. Here, the at least one elongate member extends between an access structure 208 and the fish enclosure 204. The suspension arrangement 206 may be or comprise a flexible member (e.g. a flexible elongate member) such as a wire, cord, chain, rope or the like. A flexible member may have low bending stiffness, and high axial stiffness, or vice versa. In some examples, the suspension arrangement may be or comprise a rigid member (e.g. a rigid elongate member) such as a rod, pipe, rail, rack or the like, which may extend between the collar 202 and the fish enclosure 204. A rigid member may have high axial stiffness. In some examples, the suspension arrangement may comprise a combination of flexible and rigid members, for example the suspension arrangement may comprise a rigid member extending between the access arrangement 208 and the collar 202, and a flexible member extending between the collar 202 and the fish enclosure 204.

[0362] Additionally or alternatively, the suspension arrangement 206 may comprise a spring and damper system. For example, a spring and damper system may be located between the floatable structure 201 and the fish enclosure 204, for example between the access arrangement 208 and the fish enclosure 204, for example an upper edge or side of the fish enclosure 204. The spring and damper system may comprise a biasing member of any appropriate type, such as a helical spring, a pneumatic or hydraulic cylinder, or the like. In some examples, the spring and damper system may comprise an elongate member forming part of the suspension arrangement 206. In other examples, the spring and damper system provide a direct connection between the fish enclosure 204 and the floatable structure 201 without the requirement for an elongate member in the spring and damper system. The spring and damper system may connect to the floatable structure 201 and fish enclosure 204 by any appropriate means, such as by a bracket, ties, a hook member or members, or the like. The spring and damper system may be adjustable by a user. For example, where the spring and damper system comprises a pneumatic cylinder, the air pressure therein may be able to be adjusted in order to change the damping properties thereof. In the case of a hydraulic cylinder, the size of openings therein may be able to be changed so as to adjust the damping properties.

[0363] As illustrated in Figure 26, the access structure 208 is in the form of a plurality of columns which extend from the collar 202. Here two are shown, although there may be more or fewer, depending on the design of the fish farm 200.

[0364] The vertical cross-section 220 of the collar 202 is visible in Figure 26, and in this case is rectangular, although other shapes of cross-section may be desirable. For example, the cross-section 220 may be circular, square, triangular, polynomial, or any other desired shape. The entire height of the vertical cross-section of the collar 202 is submerged, and varying the shape of the cross-section may have an effect on the hydrodynamic forces acting on the collar 202 as the fish farm 200 moves in water. The shape of the cross-section may vary along the length of periphery of the collar, or circumferentially in the case where the collar has a ring or annular shape. For example, the area and / or shape of the cross-section of the collar 202 may vary along the length of the periphery (or circumferentially) of the collar 202.

[0365] Although not illustrated, at least one of the collar 202 and the access structure 208 may comprise a ballast tank therein in some examples, which may optionally be able to be ballasted and deballasted by a user. For example, a plurality, or each, of the access structures 208 may comprise a ballast arrangement comprising at least one ballast tank that is able to be ballasted and deballasted to reconfigure the weight of the at least one ballast tank to thereby control the buoyancy of the floatable structure 201 . The level of buoyancy and positioning of such ballast tanks may be selected so as to ensure that the collar 202 remains submerged at all times, and at an appropriate level below the waterline 110 (e.g. 3 metres below the waterline), thereby assisting to ensure that the collar 202 obtains the desired hydrodynamic properties. Additionally, the ballast level of the ballast tanks may be decreased such that the collar 202 is no longer fully submerged, which may be useful for transport and maintenance, for example. The level of ballast in the ballast tanks may be selected by pumping surrounding seawater into and out of the ballast tanks, and may be variable by a user when desired. Each ballast tank may therefore comprise a pump and caisson, at least part of which may be located in at least one of the access structure and the collar. The user may therefore be able to vary the depth of the collar 202 below the waterline, which may permit further variability of the hydrodynamic and stability properties of the floatable structure 201 .

[0366] The access structure 208 or the collar 202 may comprise a height adjustment means for raising and lowering of the fish enclosure 204 relative to the collar 202. The height adjustment means may be used to vary the length (e.g. increase or decrease) of the suspension arrangement 206. In some examples, the suspension arrangement 206 and may perform the function of a height adjustment means.

[0367] The fish enclosure 204 illustrated in Figure 26 may be made from a water permeable or impermeable material (e.g. may be a fully-closed or semi-closed fish enclsoure). In Figure 26, the fish enclosure 204 is fully-closed and is made from a water impermeable material, and contains a volume of water therein, in which fish to be farmed may be contained. As illustrated, the water level 205a of the fish enclosure 204 is located at a higher level than the waterline 205 of the surrounding body of water. Having a higher water level in the fish enclosure 204 may result in the water pressure in the fish enclosure 204 being higher than that of the surrounding body of water, thereby providing a force on an internal surface of the material of the fish enclosure 204, and permitting the material of the fish enclosure 204 to be held taught, and permitting the fish enclosure 204 to hold its shape, thereby preventing fish from colliding with the material of the fish enclosure 204, and preventing damage to the fish enclosure 204 due to excessive deformation.

[0368] Also illustrated in Figure 26, the fish enclosure 204 comprises a fluid inlet 250 and a fluid outlet 252.

[0369] The fluid inlet 250 is located on an upper portion of the fish enclosure 204. In this example, the fish enclosure 204 has an open top section. The open top section of the fish enclosure 204 forms the fluid inlet for the fish enclosure 204 in this example, however it should be appreciated that in some examples the fish enclosure 204 may have a dedicated inlet 250 defined therein.

[0370] The fluid inlet 250 of Figure 26 additionally comprises an inlet conduit 254. The inlet conduit 254 extends from the fluid inlet 250 and into the surrounding body of water. The inlet conduit 254 may extend from the fluid inlet 250 to a region of the surrounding body of water that is located below the fish enclosure. In doing so, the fluid intake 251 of the inlet conduit 254 may be positioned in clean and nutrient rich water, which may also be at more stable and desirable temperature than water at the surface. The inlet conduit 254 may therefore bring clean and nutrient rich water into the fish enclosure 204 from the surrounding body of water. The inlet conduit 254 may comprise a fluid propulsion means, such as a fluid pump e.g. a submersible fluid pump, a gas lift pump or the like, in order to propel water into the fish enclosure 204. The inlet conduit 254 may be adjustable in length (e.g. may be telescopic, may comprise, or be suitable for attachment to, an extension section, or the like), and therefore the fluid intake 251 may be repositionable within a surrounding body of water, which may assist to bring water from a desired depth (e.g. and therefore at a desired temperature) into the fish enclosure 204.

[0371] The outlet 252, although not illustrated, may be similarly connected to an outlet conduit. The outlet conduit may extend at least one of vertically and horizontally, or may extend both horizontally and vertically, and may assist to deposit water flowing from the fish enclosure 204 at a location further away from the fish enclosure (or further away from the intake 251 ) than would be the case without an outlet conduit. The outlet of the outlet conduit and the intake 251 of the inlet conduit 254 may be positioned at a minimum predetermined distance, so as to prevent or reduce the volume of water flowing from the outlet 252 and returning through the inlet 250. For example, the depth of the fluid intake 251 may be increased, while the outlet conduit may extend in a horizontal distance and away from the fluid intake 251 so as to maximise the distance between the fluid intake 251 and the outlet of the outlet conduit. The intake 251 and the outlet of the outlet conduit may be variable in position. As such, having an inlet conduit 254 and optionally an outlet conduit may assist a user to reduce accidental recirculation of water from the outlet and back into the fish enclosure 204, and therefore improve hygiene standards within the fish enclosure 204.

[0372] The inlet conduit 254 may be supported by the floatable structure 201 . The inlet conduit may be, for example, supported by at least one of the access structure 208 and the collar 202 of the floatable structure 201 . The inlet conduit 254 may be attached and / or connected to the floatable structure 201 , for example the access structure 208 and / or collar 202 thereof. As shown in this example, the inlet conduit 254 extends through the floatable structure 201 - here through both the collar 202 and access structure 208, although it should be understood that the inlet conduit 254 may extend through either of the collar 202 and access structure 208. Although not illustrated, the floatable structure 201 may comprise a water treatment module therein, which may be able to treat the water flowing in the inlet conduit 254. For example, the water treatment module may comprise an inlet to the inlet conduit 254 through which treatment fluids such as disinfectant, water purifying chemicals, or the like, are able to be introduced.

[0373] The fluid outlet 252 is located on a lower portion of the fish enclosure 204. In this example, the fluid outlet 252 is located at the lowermost point, or base, of the fish enclosure 204. The fluid outlet 252 is in the form of an aperture formed in the material of the fish enclosure 252. The fluid outlet 252 may be surrounded by a reinforced portion of material, for example to increase the toughness of the fish enclosure 204 and prevent propagation of tears in the material of the fish enclosure 204. Having the fluid outlet 252 at the base of the fish enclosure 204 may assist to expel detritus such as feed particles or fish waste from the fish enclosure 204 that naturally sink towards the base of the fish enclosure 204.

[0374] Here, the fish enclosure 204 has a parabolic cross-sectional shape, which may assist in an even force distribution throughout the material of the fish enclosure 204. The parabolic shape may also assist to define a base (e.g. at the lowest point thereof) at which a fluid outlet may be positioned.

[0375] In some examples, at least one or both of the inlet conduit 254 and fluid outlet 252 may be in fluid communication with the surrounding body of water. In some examples, both the inlet conduit 254 and fluid outlet 252 may be in fluid communication with a vessel or processing plant (in the case of the fluid outlet 252 via a conduit). In this case, there may be no water exchange between the surrounding body of water and the fish enclosure 204, and as such the structure 200 may be considered to be a Recirculating Aquaculture System (RAS).

[0376] Figure 27 illustrates a further example of a fish farming structure 200. Similar to the previous example, the fish farming structure 200 comprises a floatable structure 201 comprising a collar 202 and a plurality of access structures 208. A fish enclosure 204 is suspended from the floatable structure 201 , in particular from the plurality of access structures 208 thereof, as will be described in more detail in the following paragraphs. Here, the collar has a vertical cross-section in the shape of an octagon, and may be considered to have an octagonal annulus shape. Here, an access structure 208 is located at each apex of the collar 202, although in other examples an access structure 208 may be located between apexes on the collar 202, or in the case where the collar has no apexes (e.g. is a circular or oblong shape) then the access structures 208 may simply be located on the collar 202 at desirable locations.

[0377] In both Figure 26 and Figure 27 is illustrated at least one inlet conduit 254 that the fish farming structure 200 may comprise. In Figure 26, the fish farming structure 200 may comprise one single inlet conduit 254, while in this example the fish farming structure comprises one inlet conduit 254 per two access structures 208, which here is four inlet conduits 254. The inlet conduits 254 of Figure 27 are arranged on every other access structure 208 of the floatable structure 201 , in an alternating manner such that they are evenly distributed around the floatable structure 201 . In both Figures 26 and 27, each inlet conduit 254 is supported by an access structure 208. The inlet conduit 254 in Figure 26 extends through the access structure 208 in a vertical direction, in line with, or parallel to, the longitudinal axis of the access structure 208. In Figure 27, the inlet conduit 254 extends in a horizontal direction through the respective access structure 208, e.g. perpendicular to the longitudinal axis of the access structure 208. In some examples, the inlet conduit 254 may extend through the access structure 254 at an oblique angle. The angle with the longitudinal axis of the access structure 208 through which the inlet conduit 254 extends may be selected depending on the level of support required of the inlet conduit 254, which may vary depending on the rigidity of the inlet conduit 254, and therefore this variable may enable more flexibility in the design of the floatable structure 201 .

[0378] In both Figures 26 and 27, the inlet conduit 254 extends from the access structure 208 in a downwards direction towards the fish enclosure 204, e.g. downwards towards the fish enclosure 204 and positioned radially within the collar 202. In Figure 26, the inlet conduit 254 extends downwardly at an angle perpendicular to the water level 205a of the fish enclosure 254. In Figure 27, the inlet conduit 254 comprises a first and a second downwardly extending portion. The first downwardly extending portion extends at an angle perpendicular to the water level 205a, while the second downwardly extending portion extends at an angle oblique to the water level 205a. The water exits the inlet conduit 254 from the second portion, flowing at an oblique angle to the water level 205a, which may induce a circumferentially directed flow of water in the fish enclosure 204 (relative to a vertically extending central axis of the fish enclosure 204). Having a circumferentially directed flow may provide benefits to the fish enclosure 204, for example by ensuring a high degree of water circulation throughout the entire fish enclosure 204, which assists to ensure high water quality and provides good exercise for the fish inside. In some examples, it may additionally encourage particulate matter to gather in a particular region of the fish enclosure 204, which may be near the outlet 252, and therefore may assist to further provide better hygiene within the fish enclosure 204.

[0379] The access structures 208 in Figure 27 are illustrated as being equidistantly located on the collar, although it should be noted that other configurations of access structures 208 may be possible. The illustrated access structures 208 of Figure 27 are in the form of columns having a polygonal cross-section (e.g. square, pentagonal, hexagonal, heptagonal, octagonal, or the like), which may assist in the construction of the columns, for example from panels welded together. In other examples, the access structures 208 may have a circular cross-section.

[0380] The fish enclosure 204 in this example has a horizontal cross-section that is identical in shape to the horizontal-cross section of the collar 202 of the floatable structure. In this example, an octagon. Here, as the fish enclosure 204 is suspended from each of the plurality of access structures 208 via the suspension arrangement, the suspension arrangement 208 and floatable structure 201 may assist to hold the fish enclosure in a desired shape, here having the octagonal cross-section. This configuration may additionally enable ease of access of the inlet conduit 254 to the fish enclosure 204, as the suspension arrangement 206 may hold the fish enclosure close to each access structure 208, which may support an inlet conduit 254.

[0381] In Figures 28a-c and 29a-c are illustrated various configurations of a fish farming structure 200 shown from above. In Figures 28a-c, a fish enclosure 204 having a circular cross section is shown, regardless of the shape of the respective floatable structure 201.

[0382] As illustrated in Figures 28a, 28b, 29a and 29b, the collar 202 of the floatable structure 201 comprises a square annulus shape, while in Figures 28c and 29c the collar comprises a polygonal annulus shape (specifically an octagonal annulus shape). Other shapes may be possible, such as a circular annulus shape.

[0383] As previously described, each fish enclosure 204 is suspended from the floatable structure 201 via a suspension arrangement 206. In each of Figures 28a-c (and also in Figures 29a-c), a suspension arrangement extends between the fish enclosure 204 and each of the access structures 206. In some cases, the suspension arrangement comprises one single connection member (e.g. a rope, chain, cord or the like) extending between an access structure 206 and the fish enclosure 204, and in other cases, the suspension arrangement 206 comprises a plurality (e.g. two) connection members extending between the fish enclosure 204 and the access structure 206.

[0384] In Figures 29a-c, as in Figure 27, the cross-sectional shape of the fish enclosure 204 is the same as that of the floatable structure 201 (e.g. the collar 202 of the floatable structure 201).

[0385] As can be seen in Figure 28b and 29b, the floatable structure 201 illustrates an example in which an access structure is located at each apex of the collar 202, and also between the apexes of the collar 202, in this example at a midpoint of each straight edge of the collar 202, extending vertically from the collar 202. In this example, each of the access structures 206 has a circular cross-section.

[0386] In Figures 28c and 29c, the collar 202 has an octagonal shape, whereas in Figures 28a-b and 29a-b, the collar has a square shape.

[0387] The collar 202 may be formed from one continuous member, e.g. one continuous ring-shaped member. In another example, the collar 202 may be formed from a plurality of members, e.g. elongate structures, which may be connected together to form the collar 202. The plurality of structures may be a plurality of straight elongate structures, a plurality of curved elongate structures, or a mixture of at least one straight and at least one curved elongate structure. At least one of the structures may comprise perforations, in some examples, at least one, or each, of the structures may comprise a truss structure. The collar 202 may be in the form of a pontoon, or a plurality of connected pontoon members. The collar may comprise at least one buoyancy member e.g. located therein or defined thereby, which may be integrated within the or a member that forms the collar 202, or which may be connected or fastened to the member that forms the collar 202. The at least one buoyancy member may be integrally formed with the collar 202, such that it may be considered to be a buoyant collar.

[0388] Figure 30 illustrates a further example of a fish farming structure 200. The fish farming structure 200 is similar to that of Figure 26, although the structure 200 of Figure 30 comprises a support structure 211 , which extends between the access structures 208 of the floatable structure 201 . The support structure 211 may be in the form of a beam, connector, or the like, and may be rigid. In the example of Figure 30, the support structure may function as a hang-off for the fish enclosure 204, and may be used instead of, or as well as, the access structures 208 to suspend the fish enclosure 208 from the floatable structure 201 . In this example, the suspension arrangement 206 extends between the support structure 211 and the fish enclosure 204, although in some other examples the suspension arrangement may additionally extend between an access structure or structures 208 and the fish enclosure 204. The suspension arrangement 206 may comprise a plurality of connection members extending between the support structure 211 and the fish enclosure 204. The support structure 211 may comprise a plurality of connection points onto which the suspension arrangement 206 may be able to connect.

[0389] The support structure 211 may extend between each of the access structures 208, and may have a similar shape to the collar 202.

[0390] Figures 31a-c illustrate examples of a support structure 211 on a floatable structure 201 , as viewed from above. In Figure 31 a, it can be seen that the support structure 211 has a square shape, which is the same as the shape of the collar 202. In this example, the support structure 211 has a larger length and width compared to the collar 202, and therefore is positioned outwardly of the collar 202.

[0391] In Figure 31b, the support structure 211 comprises two support members. Each of the two support members extends between two of the access structures 208, and in this example the support members and separate (e.g. not connected) to one another. Here, the support members extend across the opening of the fish enclosure 204, and the opening in the collar 202. Here, the support structure 211 may form a walkway, to enable a user to traverse between access structures.

[0392] The support structure 211 of Figure 31c comprises two support members. One of the support members is an octagon, which is the same shape as the collar 202, while the other of the support members extends between two access structures 206 across the opening in the fish enclosure 204. As such, in the example of Figure 31c, the support structure 211 may be able to be used as both a hang-off for the fish enclosure 204 and as a walkway.

[0393] Figures 32a and 32b illustrate an example of the suspension arrangement 206 in further detail. The suspension arrangement 206 may be at least partially located on the access structure 208 e.g. at least one component of the suspension arrangement 206 may be located on the access structure. The suspension arrangement 206 may comprise one, or a plurality of, connection members 206a that correspond to each access structure 208. In this example, the suspension arrangement 206 comprises two connection members 206a corresponding to the illustrated access structure 208.

[0394] The connection members may be a rope, chain, cord or the like. In some examples, for example where the connection members 206a are metal cords, the connection members may have high axial stiffness which may provide a secure connection with little effect from factors such as material creep, while in other examples, the connection members may be made from rope or a material with a lower axial stiffness, which may have a smoothing effect on motion transferred between the access structure 208 and the fish enclosure 204. A combination of high and low axial stiffness connection members 206a may be used.

[0395] The connection members 206a of the suspension arrangement 206 may extend between the floatable structure 201 (e.g. the access structure 208 thereof) in a vertical parallel direction relative to the longitudinal axis of the access structure 208, or may extend in a perpendicular direction or oblique direction relative to the longitudinal axis of the access structure 208. In this example, the connection members 206a extend in a perpendicular direction between the fish enclosure 204 and the floatable structure 201 .

[0396] The suspension arrangement of this example comprises a pulley 256, and a connection member 206a of the suspension arrangement 206 connects to the fish enclosure 204 via the pulley 256. This may assist to further provide damping of relative motion between the fish enclosure 206 and the floatable structure 201 by permitting the connection member 206a to be fed through the pulley 256 when there is tension in the connection member 206a. It may further enable a user to control the elevation of the fish enclosure 204 relative to the floatable structure 211 by permitting the connection member 206a to be fed through the pulley to raise and lower the fish enclosure relative thereto. It should be noted that there is no requirement for the suspension arrangement 206 to comprise a pulley 256, and in some examples the connection members 206a may connect to the access structure via another means, such as through a loop of metal located on the access structure 208.

[0397] In this example, the suspension arrangement 206 comprises two connection members 206a that connect to each access structure 208. Each connection member 206a comprises a pulley 256, such that in this example each access structure 208 has a first and a second pulley located thereon, which correspond to a first and second connection member 206a. The first and second connection member 206a each connect to the fish enclosure 204 at a connection point. The connection points of each may be separate, such that the suspension arrangement 206 at each access structure 208 comprises a first and second connection point. The first connection point may be located higher on the fish enclosure 204 than the second connection point.

[0398] In locating the suspension arrangement 206 on the access structure 208, the suspension arrangement 206 may be accessible to a user even when the floatable structure 201 is partially submerged. The floatable structure may be raised, for example to a maintenance draft, so as to expose more of the suspension arrangement to a user.

[0399] In Figure 33, the fish farming structure 200 is illustrated comprising a roof enclosure 258. The roof enclosure 258 may be used to prevent predators such as aerial predators from accessing the fish enclosure 204. The roof enclosure 258 may extend across substantially the entire top surface of the fish enclosure 204. The roof enclosure may be of the same shape as the horizontal cross-section of the fish enclosure 204. The roof enclosure may be made from the same material as the fish enclosure 204 (e.g. a water permeable or impermeable material), or may be of a different material compared to the roof enclosure 258, such as a more loosely woven net material.

[0400] The roof enclosure may comprise an aperture 260 or apertures therein. The aperture or apertures 260 may function to permit feedthrough of conduits, cabling or the like. In the example of Figure 33, the aperture 260 functions to permit feedthrough of an inlet conduit 254.

[0401] Illustrated in Figures 34a-c is the connection between the roof enclosure 258 and the floatable structure 201 . The suspension arrangement 206 may be configured to additionally suspend the roof enclosure 258 from the floatable structure 201 , such as from the access structure 208 of the floatable structure 201 . The roof enclosure 258 may be in physical contact with the fish enclosure 204, or may be suspended above the fish enclosure 204 such that there is an air gap between the roof enclosure 258 and the fish enclosure 204.

[0402] The suspension arrangement may be configurable to connect the roof enclosure to one, some or each of the access structures 208. As illustrated, the suspension arrangement 208 connects the roof enclosure to a top surface of the access structures 208.

[0403] In Figure 34a, each of the access structures comprises a horizontal protrusion 262. The horizontal protrusion 262 is located at an upper part of the access structure 208, in this example at the top of the access structure. The horizontal protrusion 262 comprises a base that is connected to the access structure 206 and an oppositely disposed tip. The horizontal protrusion protrudes perpendicularly relative to the longitudinal axis of the access structure 208. A connection member 206a of the suspension arrangement 206 extends from the access structure 206 and along the horizontal protrusion in the direction of the protrusion, until the tip of the protrusion. The connection member 206a extends from the tip of the protrusion 262 and towards the roof enclosure 258. In having a horizontal protrusion, the connection member 206a is able to extend vertically downwardly to connect to the roof enclosure, which may reduce tension of the roof enclosure at the connection points to the suspension arrangement 206. The length of connection member that extends between the tip 262 and the roof enclosure 258 may be able to be lengthened or shortened by pulling or releasing a section of connection member 206a from the top of the access structure 208. To facilitate movement of the connection member 206a relative to the access structure 208, a wheel or pulley may be positioned on the access structure 208, such as at the tip of the horizontal protrusion.

[0404] In Figures 34b and 34c, a configuration of suspension arrangement 206 is illustrated that is similar to that of Figures 32a and 32b. Here, the access structure 208 does not comprise a horizontal protrusion, and the suspension arrangement comprises a first connection member 206a that connects via a pulley 256 in a direction perpendicular to the longitudinal axis of the access structure 208. In addition, the suspension arrangement comprises a second connection member 206b that extends at an oblique angle relative to the longitudinal axis of the access structure 208, and also connects the roof enclosure 258 to the access structure 208. In Figure 34c the suspension arrangement 206 is illustrated as comprising a connection to the fish enclosure 206 located below the connection to the roof enclosure 258 on the access structure 208.

[0405] A further example of a roof enclosure 258 is illustrated in Figure 35. This roof enclosure 258 may be connected or attached to the floatable structure 201 as previously described. In this example, the roof enclosure 258 comprises a dome shape. The roof enclosure 258 may comprise support means in order to maintain such a dome shape. Here, the roof enclosure 258 is inflatable. Inflation of the roof enclosure 258 may hold the material of the roof enclosure 258 taught, thereby providing the illustrated dome shape. The shape of the material may be formed such that when it is taught, it naturally forms a dome shape. The material of the roof enclosure may be the same as the material of the fish enclosure 204.

[0406] The roof enclosure 258 may comprise a cavity or a plurality of cavities therein, which may be airtight. The cavity or plurality of cavities may be inflated so as to provide tension in the material of the roof enclosure. The roof enclosure 258 may comprise a layer of inflatable material (e.g. two layers of airtight material with a cavity therebetween), contained between two layers of an alternative material, which may be the water impermeable or permeable material of the fish enclosure.

[0407] The described roof enclosure 258 may be detachable from the floatable structure 201 , for example to provide access to the fish enclosure. The inflatable roof enclosure 258 may be detachable in an inflated configuration, which may assist in the detachment of the roof enclosure 258 by providing it a degree of rigidity, or by reducing its flexibility. The inflatable roof enclosure 258 may be particularly effective when it is desirable to maintain a desired water temperature in the fish enclosure 204, by keeping colder or warmer atmospheric air away from the top of the fish enclosure 204.

[0408] Figure 36 illustrates an example of a fish enclosure 204 in more detail. While the material of the fish enclosure may be homogenous (e.g. made from one type of material), in some examples the fish enclosure may be comprised of a plurality of different materials. In Figure 36, the fish enclosure 204 may be comprised of a plurality of materials. In this example, the fish enclosure is comprised of a first material and a second material. The first material is a water impermeable material, and the second material is a water permeable material.

[0409] The first water impermeable material may comprise a bottom or lower portion of the fish enclosure 204, while the second water permeable material may comprise a top or upper portion of the fish enclosure 204, and may extend above the waterline 205 in normal operation. The first material may be configurable to be located below the waterline 205, or largely located below the waterline 205, while the second material may be configurable to be located above the waterline (e.g. entirely above the waterline) during normal use of the fish enclosure 204. As such, during normal operation, the surrounding water, as well as any macroscopic organisms therein, may be prevented from entering the fish enclosure 204 through the first material. Water, however, may be able to pass through the upper portion of the fish enclosure 204 that is located above the waterline.

[0410] In having a fish enclosure 204 that is comprised of a first and second material as described, water may be able to escape from the fish enclosure 204 through the upper portion thereof. This may be useful in the case where a large wave causes excess water to enter the fish enclosure, or in the case where the water outlet from the fish enclosure becomes blocked, as it will automatically prevent the fish enclosure from overflowing over the top of the fish enclosure which may risk fish escape, or of the water pressure in the fish enclosure 204 becoming too high and damaging the material thereof.

[0411] The example of Figure 37 is another in which the closed fish enclosure 204 comprises both a first and a second material. In this example a midsection of the fish enclosure 204, which may be configurable to be submerged during normal operation, may be made from a water permeable material, while an upper and a lower portion may be made from a water impermeable material. As the fish enclosure 204 is a closed fish enclosure, the submerged midsection (although water permeable) may still prevent the passage of macroscopic organisms therethrough.

[0412] The midsection, being water permeable, may permit a flow of water from the surrounding body of water through the fish enclosure 204, thereby reducing load on pumps that may be required to pump water through water inlet, illustrated in Figure 37 by arrows 264, and permitting the fish enclosure 204 access to water from the surrounding body of water in times of inactivity of the pumps (e.g. due to maintenance, a blockage in the inlet our outlet, or the like).

[0413] The lower section, made from a water impermeable material, may have a conical shape (as also illustrated in previous examples) which may assist to direct waste, detritus or other particulate matter towards a water outlet, which may be located at the base, which may be considered to be the apex of the conical lower section. Once at the outlet, the waste may be released to the surrounding body of water, or may be processed. Having the option to process the waste may provide a more environmentally friendly solution to waste disposal, and in some instances may be necessary, for example due to local regulations. Figure 38 illustrates a configuration for removing mort and other waste from a fish farming structure 200, which is similar to that described in Figure 27. Here, the fish farming structure 200 comprises a waste removal arrangement 266 comprising a waste removal conduit 268, which may extend from the base of the fish enclosure 204 to the floatable structure 201 , in some examples an access structure 208 thereof. In this example, the waste removal arrangement 266 is located (e.g. fully or at least partially located) inside an access structure. The waste removal conduit 268 may extend through the fish enclosure 204. The waste removal conduit 268 may extend from an outlet in the fish enclosure 204. The waste removal arrangement 266 may be considered to be, or to form part of, a mort collection arrangement.

[0414] The waste removal conduit 268 extends to a separation chamber 270 located in the floatable structure 201 , in this example in the access structure 208, but may be located in the collar 202, for example. The floatable structure 201 may comprise a waste inlet 272 for receiving the waste removal conduit 268, and providing access to the separation chamber 270. The separation chamber 270 may be completely contained within an access structure 208. The separation chamber 270 receives fluid flow from the fish enclosure 204, and the fluid collects in the separation chamber 270. The separation chamber may comprise a sump for allowing particulate matter to settle out of the fluid in the separation chamber and collect in the base thereof. The sump may be located at the base of the separation chamber, and may be the shape of an inverted cone or pyramid.

[0415] The separation chamber 270 may additionally comprise a waste outlet 274, and a waste outlet conduit 276 for removal of waste from the separation chamber 270. Here, the waste outlet conduit 276 comprises a fluid propulsion means 278 such as a fluid or centrifugal pump for removing water from the separation chamber 270 to an external location. The water may be pumped directly into the surrounding body of water, or may be pumped to a vessel, platform, processing plant or the like for further processing.

[0416] The waste inlet 272 and waste outlet 274 may comprise a pressure seal so as to create a pressure sealed separation chamber 270. As such, operation of the fluid propulsion means 278 may create a suction within the separation chamber 270, and at the inlet to the waste removal conduit 268, thereby removing the need for the waste removal conduit 268 to have a dedicated pump associated therewith, or comprised therein. Alternatively, the waste removal conduit 268 may be configured to extend below a water level inside the separation chamber 270. As such, removal of fluid from the separation chamber 270 may similarly create a suction at the outlet and inlet of the waste removal conduit 268.

[0417] In some examples the waste removal conduit may comprise a gas lift pump, to encourage a flow of water therethrough.

[0418] In some examples, the waste outlet 274 and / or waste outlet conduit 276 may comprise fluid purification means, such as a chemical (e.g. chlorine) injection point, to purify water flowing from the waste outlet 274. According to a further example, there is provided a fish farming structure for a closed fish farm, comprising: a floatable structure comprising a collar; a closed fish enclosure configurable to be suspended from the floatable structure via a suspension arrangement; the collar defining an access opening therein for providing access to the fish enclosure; the closed fish enclosure comprising an upper and a lower portion, the upper portion extending between the floatable structure and a connection to a structural frame, and the lower portion extending from the connection to the structural frame to form a base of the closed fish enclosure.

[0419] Figures 39a-c illustrate an example of a fish farming structure 300 comprising a floatable structure 301 having a closed fish enclosure 304 suspended therefrom, the closed fish enclosure 304 comprising an upper portion 304a and a lower portion 304b. The upper portion 304a extends between the floatable structure 301 and a connection to a structural frame 380, while the lower portion 304b extends from the connection and forms a base of the fish enclosure 304.

[0420] The structural frame being connected to the closed fish enclosure 304 may assist to hold the material of the closed fish enclosure 304 in tension, thereby preventing collapse of the closed fish enclosure 304, or deformation of the fish enclosure 304 due to currents or changes in water pressure within the fish enclosure 304. As such, the structure 380 may reduce the importance of having a high relative water pressure in the closed fish enclosure 304 relative to the surrounding body of water in order to prevent unwanted deformation of the fish enclosure 304. In addition, the structural frame 380 may hold the closed fish enclosure 304 in a desired configuration, form or shape which may assist, for example, in providing a preferential water flow within the fish enclosure 304 and / or improving hygiene within the closed fish enclosure 304, as will be described in more detail in the following description.

[0421] Figures 39a-c illustrate various examples of a fish farming structure 300 comprising a closed fish enclosure 304 comprising a structural frame 380. Many features described in relation to this example are similar to those described in relation to Figures 26 to 38, and therefore alike reference numerals will be used for these features, augmented by 100.

[0422] In Figure 39a, the fish farming structure 300 is illustrated as having a floatable structure 301 , which in this example comprises a collar 302. In contrast to some previously described examples, the floatable structure 301 of Figure 39a comprises only a collar and does not comprise an access structure. In addition, the collar 302 of Figure 39a is configurable to float on a waterline 305 in normal operation (e.g. in an operational draft), and may not be submerged as described in the previous and following examples. Although not illustrated, the collar 302 may comprise a railing, frame or the like on an upper surface thereof to assist an operator to walk thereon. The upper surface may be the surface that is located above the waterline, and in some examples may be a surface that is flat (e.g. horizontally oriented).

[0423] The collar 302 may be or comprise an annular shape, and may have a circular, square, rectangular, polygonal or other shape. Where the cross-section is a square, rectangular or polygonal shape, the upper surface of the collar 302 may be that which is horizontally oriented.

[0424] The closed fish enclosure 304 is suspended from the floatable structure 301 from a suspension arrangement. The suspension arrangement is not illustrated in Figure 39a, although may be similar or the same as that described previously, for example in Figures 32a and 32b.

[0425] The upper portion 304a of the closed fish enclosure 304 in the example of Figure 39a (and in Figures 39b and c) may be configurable to define a volume of a prismatic or extruded shape. For example, where the horizontal cross-section of the fish enclosure 304 is circular in shape, then the upper portion 304a of the closed fish enclosure 304 may be in the shape of a sleeve, and may define a cylindrical volume. Where the horizontal cross-section is a square or rectangle, the upper portion 304a may define a cube or rectangular prism volume. The width and length, or in the case where the upper portion 304a comprises a circular or oval shape horizontal cross-section, the (major and minor) diameter of the upper portion 304a may vary with height. For example the upper portion 304a may comprise or define a truncated cone or pyramidal fluid volume. In the case of a truncated pyramid, the base of the pyramid may be the shape of the horizontal cross-section of the upper portion 304a. The upper end of the upper portion 304a may comprise an opening for providing access to the fish enclosure 304, for example that is located at the surface, e.g. located above the waterline 305. The lower end of the upper portion 304a may comprise an opening to the lower portion 304b of the fish enclosure 304.

[0426] The lower portion 304b may define a pyramidal or conical fluid volume. Alternatively the lower portion 304b may define a semi or partial spherical fluid volume, or a cubic, rectangular prism or polyhedral volume. The lower portion 304b may comprise one opening therein, which opening may be to the upper portion 304a of the fish enclosure 304. The opening may be located at an upper end of the lower portion 304b. At a lower end of the lower portion 304b may be a closure, which may be formed by the material of the fish enclosure 304. The closure may be formed by the tip of the cone or pyramid of the lower portion 304b, by the curve of the lower portion 304b when the lower portion 304 has a semi or partial sphere shape, or by a section of material where the lower portion 304 has a cubic, polyhedral or rectangular prism shape.

[0427] The lower portion and the upper portion 304a, b may be made from the same material. In some examples, the lower portion and the upper portion 304a, b may be made from the same sheet of material. In other examples, the upper portion 304a and the lower portion 304b may be made from separate sections of material.

[0428] Connected to the closed fish enclosure 304 is a structural frame 380. The structural frame 380 may be rigid or flexible. In this example, the structural frame 380 is connected to the fish enclosure 304 at the boundary between the upper portion 304a and the lower portion 304b. The structural frame 380 may be in the form of a ring or loop of material. The structural frame 380 may be in the form of an endless ring or loop, or may have a discontinuity therein, such that the structural frame 380 comprises a C- or U-shape. The structural frame 380 may extend around the periphery of the fish enclosure 304. The structural frame 380 may extend continuously or discontinuously, for example in a plurality of discontinuous segments. The structural frame may have a shape that is the same or similar to the shape of the horizontal cross-section of the fish enclosure 304 (e.g. the upper part of the fish enclosure 304a).

[0429] The structural frame 380 may connect directly to the fish enclosure 304 as is the case in Figure 14c, or may comprise a connection arrangement that connects the structural frame 380 to the fish enclosure 304.

[0430] Where the structural frame 380 connects directly to the fish enclosure 304 such that it is in contact therewith, the frame 380 may connect to an outer surface of the fish enclosure 380, and may be held in place by ties, connection loops or the like. In some examples, the structural frame 380 may be located between the upper portion 304a and the lower portion 304b, such that the structural frame 380 separates the upper portion 304a from the lower portion 304b.

[0431] In the examples of Figures 39a and 39b, the structural frame 380 is connected to the fish enclosure 304 via a connection arrangement 382. The connection arrangement may comprise a connector or plurality of connectors such as a cable, rope, cord, tie or the like that connects the structural frame 380 to the fish enclosure 304. The connector or connectors may connect directly to the fish enclosure 304.

[0432] In some examples, the connection arrangement 382 may comprise a secondary frame that connects directly to the fish enclosure 304. The secondary frame 304 may be connected to the structural frame 380 by a connector such as a cable, rope, cord, tie or the like. The secondary frame may have the same shape as the horizontal cross-section of the fish enclosure 304. The secondary frame may be rigid, and may assist the fish enclosure 304 to maintain a desired shape.

[0433] To further assist the fish enclosure 304 to hold a desired shape, the fish enclosure 304 may comprise a reinforcement band or a plurality of bands. The reinforcement band may be a band of metal or polymer with some rigidity that is integrated into, or connected to, the material of the fish enclosure. The reinforcement band may extend circumferentially. A reinforcement band may be oriented horizontally, parallel to the waterline and / or to the collar of the floatable structure 301 . A reinforcement band may extend obliquely to the waterline and / or collar.

[0434] The structural frame 380 may be suspended from the fish enclosure 304, as is illustrated in Figures 39a and b. The structural frame 380 may be suspended from the fish enclosure 308 by the connector or plurality of connectors. The structural frame 380 may be suspended from the fish enclosure 304 by the connection arrangement 382. The structural frame 380 may be suspended from the secondary frame. The structural frame 380 may be suspended below the level of the lower portion 304b of the fish enclosure 304. The structural frame 380 may be connected to the fish enclosure 304 to permit relative motion between the structural frame 380 and the fish enclosure 304, which may enhance any damping effect the structural frame 380 has on the motion of the fish enclosure 304.

[0435] The structural frame may be negatively buoyant, and therefore the weight of the structural frame 380 may assist to hold the fish enclosure 304 in tension, thereby holding its shape. In other examples, the structural frame may be neutrally or positively buoyant.

[0436] As illustrated in Figures 39b and c, the floatable structure 301 may comprise a collar 302 and an access structure 308, or a plurality of access structures 308, such that the collar 302 is completely submerged as has been described in relation to the previous Figures.

[0437] Figure 40 is a perspective illustration of a fish farming structure 300 comprising a floatable structure 301 and a fish enclosure 304, the fish enclosure 304 comprising a structural frame 380. The floatable structure 301 is similar to that described in Figure 27, and comprises a collar, a plurality of access structures 308 and a plurality of inlet conduits 354, the inlet conduits 354 being arranged on each access structure 308 in an alternating configuration, such that each access structure 308 supporting an inlet conduit 354 is adjacent two access structures 308 without an inlet conduit 354, and vice versa.

[0438] Also illustrated, the inlet conduits 354 are connected to the structural frame 380, and therefore the structural frame 380 may assist to keep the inlet conduits 354 stable in the body of water, and reduce the effects of currents on the inlet conduits 354.

[0439] Figure 41 illustrates schematically an example of a fish enclosure 304 as viewed from above. In this example, fish enclosure 304 has a rectangular cross-section. In this illustration, the circulation of water in the fish enclosure 304 is shown by arrow 384. The water in the fish enclosure may be circulated by any appropriate means, such as by a fluid pump or arrangement of fluid pumps or fluid inlets positioned inside or above the fish enclosure (see Figures 26, 27 and 40, for example), and configured to generate a flow of water in the fish enclosure 304. Having a flow of water in the closed fish enclosure 304 may provide benefits, such as permitting better oxygenation of the water, and providing a more habitable environment for any fish inside the fish enclosure. Having a closed fish enclosure 304 may improve or enable water circulation therein, as momentum within the volume of water in the fish enclosure 304 may be built without significant losses due to large volumes of water exiting the fish enclosure 304.

[0440] The example of Figure 41 illustrates an additional benefit that may be possible when inducing water circulation within a closed fish enclosure 304, an in particular in a closed fish enclosure of a polyhedral shape, or that had a polygonal horizontal crosssection which may be made possible by the inclusion of a structural frame 380. In this case, the shape of the fish enclosure 304 defines a main flow region 386a located in the centre of the fish enclosure 304, in this case centrally located around the longitudinal axis of the fish enclosure 304, and at least one peripheral flow regions 386b. The at least one peripheral flow region may be located adjacent the, or each, apex defined by the fish enclosure 304 (e.g. defined by the horizontal cross-section of the fish enclosure 304). In this case, there are four peripheral flow regions 386b located at each corner of the fish enclosure 304.

[0441] Fluid flow velocity may be lower in the peripheral regions 386b compared to the main flow region 386a, and / or may be more turbulent than in the main flow region 386a. Once the main flow region 386a is established, the peripheral flow regions 386b may form naturally at the corners or apexes of the fish enclosure 304. In some examples, at least one flow obstructer 388 may be positioned to assist in slowing the fluid flow in the peripheral regions 386b and / or to assist in producing turbulent flow in a peripheral region 386b. At least one flow obstructer 388 may be positioned in the fish enclosure 304 in order to establish a peripheral flow region 386b located at an edge of the fish enclosure 304 (e.g. not adjacent a corner or apex).

[0442] Having a peripheral region 386b as described may assist to improve hygiene standards within the fish enclosure 304 by facilitating the cleaning of the fish enclosure 304. For example, sediment material such as uneaten food, fish waste or other detritus may naturally settle in the peripheral regions 386b, thereby providing regions of the enclosure 304 that may be targeted for cleaning, and at the same time meaning that the main flow region 386 is required to be cleaned less frequently. Further, the circular motion of the water in the main flow region 386a additionally creates a centrifugal force on particles suspended in the water, thereby further encouraging particles to settle in the peripheral flow regions 386b.

[0443] Although not illustrated, a partition (e.g. made from net or sheet material) may be positioned in this fish enclosure 304, or any other fish enclosures described previously or in the following paragraphs, to form at least one sub-enclosure inside the fish enclosure.

[0444] In Figure 42 there is illustrated a fish farming structure 304, showing two examples of an inlet conduit 354 secured to both the floatable structure 301 and the fish enclosure 304. On the left side of the Figure, an inlet conduit 354 is illustrated being supported by both the structural frame 380 and the floatable structure 301 , and in particular an access structure 308. As described in relation to Figure 26, the inlet conduit 354 extends vertically through the access structure 308. Here, the inlet conduit 354 extends through the structural frame 380, and therefore the structural frame 380 may comprise an aperture or opening through which the inlet conduit 354 extends. In some examples, the inlet conduit 354 may be held in tension between the floatable structure 301 and the structural frame 380, and as such compression of the material of the inlet conduit 354 may be avoided, as may kinks in the material. The fluid inlet may be located below the fish enclosure 304, at a lower end of the inlet conduit 354.

[0445] On the right side of the Figure, an inlet conduit 354 is illustrated as being attached to the floatable structure 301 , e.g. directly attached. However, in this case, the inlet conduit 354 is attached to the side of the access structure 308, and does not extend through the access structure 308. The inlet conduit 354 may be held in place by a tie or loop of material on the access structure 308. Similarly, the inlet conduit 354 is attached to the side of the structural frame 380, and does not extend therethrough. In this case, the structural frame 380 comprises a sleeve 392 connected thereto, through which the inlet conduit 354 is threaded. The sleeve 392 may be connected to the structural frame 380 by any appropriate means, such as by a tie, bolt, rigid connector, weld or the like. Although not illustrated, the inlet conduit 354 may run along a top or upper surface of the connected access structure 308.

[0446] The inlet conduit 354 may have a bend stiffener 390 at the inlet end thereof. In some examples, the inlet conduit 354 may be connected to an inlet hose, which may extend deeper into the body of water. In such examples the inlet conduit 354 may act as a bend stiffener for the inlet hose.

[0447] The illustration of Figure 43 shows a fish farming structure 300 having a fluid inlet conduit 354 extending horizontally through an access structure 308, for example as illustrated previously in Figure 27. Here, the fish farming structure 300 also comprises a fluid outlet conduit 392. Although in many of the described Figures, only one fluid inlet conduit 354 and one fluid outlet conduit 392 are illustrated, it should be noted that a plurality of each or either may be present, and for example may be circumferentially disposed about the fish enclosure 304, such as in an even distribution. Both the inlet to the inlet conduit 354 and the outlet of the outlet conduit 392 are located below the waterline 305 so as to retrieve and deliver water directly to and from the surrounding body of water. The inlet conduit 354 and outlet conduit 392 (or pluralities thereof) may establish at least one flow path through the fish enclosure 304, extending from the outlet of the fluid inlet 354 to the inlet of the outlet conduit 392. As illustrated, the outlet of the fluid inlet 354 may be located higher than the inlet of the fluid outlet 392 in the fish enclosure, for example the outlet of the fluid inlet 354 may be located at the top, or in the upper half, of the fish enclosure 304, while the inlet of the fluid outlet may be located at the bottom, or in the lower half, of the fish enclosure 304, thereby extending the length of a flowpath extending therebetween.

[0448] The fluid volume located in the vertical section of the fish enclosure located between the outlet of the fluid inlet 354 and the inlet of the fluid outlet 392 may be considered to form part of a flow path between the inlet conduit 354 and outlet conduit 392. This section of the fish enclosure 304 may define a transient water volume 396a. Located below the inlet to the outlet conduit 392 may be a region of relatively low flow, which may be considered a static water volume 396b. The static water volume 396b may be located outside of the flow path within the fish enclosure 304, and may function as a sump, in that it permits sedimentation of particulate matter such as fish waste, food particles or the like in the fish enclosure 304. The transient water volume 396a may have a high exchange rate of water between the surrounding body of water and the fish enclosure 304, and therefore may comprise a higher water oxygenation level, lower waste levels, and the like, therein, which is better for fish welfare.

[0449] Here, the fluid outlet conduit 392 comprises a fluid propulsion means 394, which in this example is a fluid pump. The fluid propulsion means 394 may be selectively controllable by a user, for example a user on a nearby vessel on located on the floatable structure 301 . The flow rate through the fluid outlet 392 may be controlled by a user. The flow rate through the fluid outlet 392 may be varied between zero and a maximum flow rate that may be determined by the limitations of the fluid propulsion means 394. The fluid propulsion means 394 may be used to vary the volume of water in the fish enclosure 304. As the fish enclosure 304 comprises a structural frame 380, there may be less reliance on a high water pressure inside the fish enclosure 304 to maintain its shape. Therefore, when used in combination with a structural frame 380, the fluid outlet 392 and fluid propulsion means 394 may be used to control the water level inside the fish enclosure 304, and may permit a water level 305a inside the fish enclosure 304 that is lower than the waterline 305 as illustrated, or a higher water level if required.

[0450] The outlet of the inlet conduit 354 is located below the water level 305a, and in this example, the inlet conduit 354 does not comprise a fluid propulsion means. As the water level 305a inside the fish enclosure 304 is lower than the waterline 305, the siphon principle may be used to generate a flow of water into the fish enclosure 305 through the water inlet conduit 354, thereby omitting the requirement to have a fluid propulsion means. It should be noted that the outlet of the inlet conduit 354 can be positioned proximate the water level 305a, or may extend much deeper into the fish enclosure 304, and the outlet may be located at a midsection of the depth of the fish enclosure 304, or proximate the base of the fish enclosure 304. Where the inlet conduit 354 comprises fluid propulsion means or otherwise does not rely on the syphon principle, the outlet may be located above the waterline 305a.

[0451] Although in Figure 43, the fluid inlet conduit 354 is illustrated without a fluid propulsion means, while the fluid outlet conduit 392 comprises a fluid propulsion means, the opposite may also be the case. In such a case, the inlet conduit 354 would drive a fluid flow into the fish enclosure 304, while the fluid outlet conduit 392 may be a simple conduit, optionally with a valve therein to block or restrict flow therethrough if required. In this example, the fluid pressure inside the fish enclosure 304 may be required to be higher than the external body of water in order to induce a fluid flow through the outlet conduit 392.

[0452] Located at the base of the fish enclosure 304 is a waste outlet 398. The waste outlet may permit removal of sedimentation from the fish enclosure 304. The sedimentation may be in the static water volume which may be located adjacent the waste outlet 398. A waste removal conduit 368 is connected to the waste outlet 398, which may be similar to that illustrated in Figure 13, although in this example the waste removal conduit 368 extends outside of the fish enclosure from the waste outlet 398 to the floatable structure 301 , here an access structure 308 thereof. Inside the access structure 308 may be a separation chamber, also similar to that as described in relation to Figure 38. Here, the waste removal conduit comprises a fluid propulsion means in the form of a fluid pump such as a submersible pump 365, a gas lift pump, or the like. In other examples, the fluid propulsion means may be located inside a separation chamber in the access structure 308 (as described in relation to Figure 38), thereby creating a vacuum pressure within the separation chamber and establishing a fluid flow in the waste removal conduit 368.

[0453] In this example, the waste removal conduit 368 extends below the structural frame 380, and the structural frame is located below the upper portion 304a, but higher than the lowest point of the lower portion 304b of the fish enclosure 304. In some other examples, the waste removal conduit 368 may extend above the structural frame 380.

[0454] According to a further example, there is provided a fish farming structure for a closed fish farm, comprising: a floatable structure comprising a collar (and optionally an access structure); a closed fish enclosure configurable to be suspended from the floatable structure via a suspension arrangement; the closed fish enclosure comprising a first enclosure and a second enclosure, an intermediate water volume being defined between the first closed enclosure and the second closed enclosure, and at least one of the first enclosure and the second enclosure being a closed enclosure.

[0455] In Figure 44 there is illustrated a fish farming structure 400 comprising both a first and a second closed enclosure. The first farming structure 400 comprises a floatable structure 401 and a closed fish enclosure 404, the closed fish enclosure comprising a first closed enclosure 404a and a second closed enclosure 404b, with an intermediate water volume 415a being contained and defined between the first enclosure 404a and the second enclosure 404b.

[0456] Many features described in relation to this example are similar to those described in relation to Figures 26 to 38, and Figures 39 to 43, and therefore alike reference numerals will be used for these features, augmented by 300 relative to Figures 26 to 38, and augmented by 200 relative to Figures 39 to 43.

[0457] As previously described, the fish farming structure 400 comprises a floatable structure 401 comprising a collar 402, and optionally an access structure 408, although in this example only a cross-section of the collar 402 is illustrated for reasons of clarity.

[0458] In the example of Figure 44, the fish enclosure 404 comprises a first closed enclosure 404a that is completely contained within a second enclosure 404b. As will be described in the following paragraphs, the first enclosure 404a may not be completely contained within the second enclosure 404b. In some examples, the first enclosure 404 may be partially contained within the second enclosure 404b. The first and second closed enclosures may be fully-closed enclosures.

[0459] In the example of Figure 44, the first and second enclosures 404a, b have similar shapes. Here, the second enclosure 404b is larger than the first enclosure 404a, although in some other examples the second enclosure 404b may be smaller than the first enclosure 404a.

[0460] Similar to the illustration of Figure 26, the first and second enclosures 404a, b have a dome shape, which may be semi-spherical, or partial-spherical, although other shapes of enclosure 404 may be possible, as will be described.

[0461] The water volume 415a inside the first enclosure 404a may exert a pressure on the material of the first enclosure 404a, thereby causing a tension in the material of the first enclosure 4O4a, which may assist the first enclosure 404a to hold its shape. Similarly, the intermediate water volume 415a may exert a pressure on the material of the second enclosure 404b, thereby causing a tension in the material of the second enclosure 404b. The intermediate water volume 415a may additionally exert a pressure on the first enclosure 404a, in a direction towards the centre of the water volume 415a that will act to deform the first enclosure 404a. Therefore, it may be desirable to ensure that the pressure in the water volume 415 at a given depth is greater than the pressure in the intermediate volume 415a at that depth. As such, the water level 405a of the water volume 415a may be configurable to be higher than that of the intermediate volume 415b, as illustrated in Figure 44, thereby ensuring that the first enclosure 404a is able to hold its shape, and the material thereof to be held in tension. Equally, the surrounding body of water will exert a pressure on the second enclosure 404b in this example, where there are two enclosures 404a, b. As such, it may be desirable to ensure that the water level 405b of the intermediate volume 415b is higher than that of the surrounding body of water, as is also illustrated in Figure 19.

[0462] The intermediate volume 415b may be circulated, for example a fluid propulsion means may be positioned in the intermediate water volume 415b to circulate the water therein. The fluid propulsion means may be positioned, for example, on the floatable structure 401 or on one or both of the enclosures 404a, b themselves. In examples wherein the first closed enclosure 404a is water permeable, there may be fluid flow between the first and second fish enclosures 404a, b which may be increased by circulating the water in the intermediate water volume 415b.

[0463] In Figure 45, the fish farming structure 400 of Figure 44 is illustrated with a third closed enclosure 404c. Although in Figures 44 and 45, two and three closed enclosures are illustrated, the first farming structure 400 may comprise a plurality of enclosures of any number, for example 4, 5 or more enclosures.

[0464] The third enclosure 404c is a partial closed enclosure. A partial closed enclosure 404c may be a closed enclosure that is connected to an adjacent fish enclosure so as to form a boundary of the water volume therein, such as is illustrated in partial enclosure 404c which connects to the adjacent second enclosure 404b to form a boundary of the intermediate water volume therein, in this case a lower boundary. The volume of the intermediate water volume of a partial enclosure 404 may be less than that of a full enclosure 404a, b. The fish farming structure may comprise one or a plurality of full closed enclosures 404a, b as illustrated in Figure 44, and optionally one or a plurality of partial closed enclosures 404c.

[0465] A partial closed enclosure may be connected to an outer surface of an adjacent enclosure 404 as illustrated in Figure 45, or to an inner surface.

[0466] A partial enclosure may be connected to the surface of an adjacent enclosure 404 by any appropriate means, and the seal may be water impermeable, for example in the case where the material of the closed enclosure 404 is also water impermeable.

[0467] The use of a partial closed enclosure may provide the closed fish enclosure 404 with additional protection. A partial closed enclosure may be positioned at an area such as at the waterline 405 where the fish enclosure 404 may be vulnerable to collisions with ice or flotsam, to oil slicks or pollution from other floating chemicals, or to sea lice. Additionally or alternatively, a partial closed enclosure may be positioned around an aperture in an enclosure 404, such as a fluid inlet or outlet, which may provide additional toughness to the fish enclosure 404.

[0468] In this example, the third closed enclosure 404c encloses an upper portion of the second enclosure 404b, while the lower portion of the second enclosure 404b is located outside of the second enclosure 404b. The third enclosure 404c in this example encloses an annular water volume between the second enclosure 404b. It should be noted that this configuration is not limited to being between a second and third enclosure, and may be between a first and second, or third and fourth enclosure, for example.

[0469] Figures 46 and 47 illustrate further examples of partial enclosures. In this example, the fish farming structure 400 comprises a first enclosure 404a, which is a full closed enclosure, and a second enclosure 404b, which is a partial closed enclosure.

[0470] In Figure 46, the partial enclosure 404b is completely submerged, and is in a location that is completely below the waterline 405 in contrast to the partial enclosure of Figure 45 which is partially submerged, and partially located above the waterline 405.

[0471] The first enclosure 404a comprises an outlet 452, which in this example is located at the base of the first enclosure 404a. The second enclosure 404b, which is a partial enclosure, is located on an outer surface of the first enclosure 404a. The second enclosure 404b is located around the periphery of the outlet 452, and therefore may assist to improve the toughness of the first enclosure 404a, which may be more susceptible to tears or damage as a result of increased exposure to particulate matter in water flowing through the outlet 452. Although illustrated as surrounding an outlet 452 on the base of the first enclosure 404a, the partial enclosure 404b may be positioned around an inlet or outlet, which may be anywhere on an adjacent enclosure (e.g. the upper or lower half, the side, etc.) and not necessarily at the base.

[0472] Figure 47 illustrates an example of a partial enclosure 404b, which in this example is also a second enclosure, and an adjacent first enclosure 404a. Both a plan and elevation view are illustrated. Here, the floatable structure 401 has a cross-section of a circular annulus, and the first enclosure 404 has a circular cross section. In this example a partial enclosure 404b is illustrated that extends from the base of the first enclosure 404a to the waterline 405. In contrast to a full enclosure, the partial enclosure 404b extends around a partial circumference of the first enclosure 404a. A partial enclosure 404b may extend partially around at least one of the height and circumference of an adjacent full enclosure.

[0473] The fish farming structure 400 of Figure 48 comprises a first enclosure 404a located inside a second enclosure 404b. Here, the fish enclosure 404 comprises a structural frame 480, similar to that as described in relation to Figures 14a and b. The structural frame is connected to the fish enclosure 404, and in this example is connected to the first fish enclosure 404a. The second enclosure 404b is located outside of the first enclosure 404a, and also connects to the structural frame 480. Here, the second enclosure 404b connects directly to the structural frame, whereas the first enclosure 404a connects to the structural frame 480 via a connection arrangement 482. The connection arrangement 482 may be or comprise a connector, which may be a tether, a tie, a rigid connector or a flexible connector, a rod, a rope, a cord, cable or the like. It should be noted that in some examples, it may be possible to connect both the first and second enclosures 404a, b (and any further enclosures, should they be present) directly to the structural frame 480. Equally, it may be possible to connect the first, second and any further enclosures 404a, b to the structural frame 480 via a connector.

[0474] In this example, the first enclosure 404a is a closed enclosure, and may or may not be water impermeable. In contrast, the second enclosure 404b may be made from a net which may permit both the flow of water and macroscopic organisms therethrough, while the closed enclosure 404a may prevent the traverse of macroscopic organisms therethrough.

[0475] As explained previously, where the fish enclosure 404 comprises a structural frame 280, there is a reduced requirement to maintain a pressure differential between the inside and outside of each enclosure 404a, 404b in order to hold the shape of the enclosure. Therefore, for the fish farming structure 400 of Figure 48, there is no requirement to have a higher water level in the fish enclosure 404 relative to the waterline 405, or in the first enclosure 404a relative to the second enclosure 404b.

[0476] Having a structural frame 480 in combination with the fish farming structure 400 may also permit one of the enclosures to comprise a net material, which may be a sufficiently open net so as to permit the passage of macroscopic organisms therethrough (e.g. may be an open fish enclosure, or may be a semi-closed enclosure where the net material is close enough to prevent passage of other matter such as leftover feed therethrough). Having an enclosure comprising a net material may result in pressure acting on the inside of the enclosure being the same as the pressure acting on the outside of the enclosure. Having an enclosure made from or comprising net material may permit the enclosure to be more cheaply and simply constructed and installed, while providing a degree of protection to an enclosure located internally thereof. For example, such a net enclosure may prevent or restrict direct contact between a closed fish enclosure and larger sea creatures or debris, which may damage the closed enclosure (which may be a fully-closed enclosure, or a semiclosed enclosure) if they were to come into direct contact therewith.

[0477] Also illustrated in Figure 48 is the connection of both the first enclosure 404a and the second enclosure 404b to the floatable structure 401 . Both the first and second enclosures 404a, b may be suspended from the floatable structure 401 . The first enclosure 404a may be suspended from the access structure 408 of the floatable structure 401 as illustrated in Figure 48, or may be suspended from the collar of the floatable structure 402. The first enclosure 404a may be suspended via a rigid or flexible connector such as a rope, bracket, connector rod, cord, cable, or the like. The first enclosure 404a may be suspended from the floatable structure 401 via a suspension arrangement 406, for example as illustrated and described in reference to Figures 32a and 32b. The first enclosure 404a may be suspended from the floatable structure 401 via suspension connection such as a bracket, loop or hook (or a plurality thereof) located on the floatable structure and, for example, optionally via a rope, cable, cord or the like attached thereto, optionally comprising a stopper therein or loop thereon for engagement with the suspension connection on the floatable structure 401.

[0478] The second enclosure 404b may be suspended from the access structure 408 or may be suspended from the collar 402, as in the example of Figure 48. The second enclosure 404b may be suspended via a rigid or flexible connector, such as a rope, bracket, connector rod, cord, cable, or the like. The second enclosure 404b may be suspended from the floatable structure 401 via a suspension arrangement 406, for example as illustrated and described in reference to Figures 32a and 32b. The second enclosure 404b may be suspended from the floatable structure 401 via suspension connection such as a bracket, loop or hook (or a plurality thereof) located on the floatable structure and, for example, optionally via a rope, cable, cord or the like attached thereto, optionally comprising a stopper therein or loop thereon for engagement with the suspension connection on the floatable structure 401 .

[0479] In this and the previously described examples, the first enclosure 404a may be positioned at least a predetermined minimum distance from the second enclosure 404b. The distance between the first enclosure 404a and the second enclosure 404b may be substantially constant across the entire area of the first and second enclosures 404a, 404b. Alternatively, the distance between the first and second enclosures 404a, b may vary across the volume of the first and second enclosures. For example, the distance between the first and second enclosures may increase or decrease with depth below the waterline 405. The distance between the first and second enclosures may be greatest at the point of contact of the first and second enclosures 404a, b and the structural frame 480. The distance between the first and second enclosures 404a, b may be greatest at the base and smallest at a top edge of the fish enclosures, or vice versa.

[0480] Illustrated in Figures 49a and 49b are examples of a fish enclosure 400. The fish enclosure 400 in both examples comprises a first and second enclosure 404a, b and in both examples the second enclosure 404b is connected to the structural frame 480 via a connection arrangement 482. In the example of Figure 49a, the connection arrangement 482 additionally connects the first enclosure 404a to the structural frame 480, whereas in Figure 49b, only the second enclosure 404b is connected to the structural frame 480. In the example of Figure 49a the connection arrangement 482 may comprise a first connection point to the first enclosure 404a and a second connection point to the second enclosure 404b. The connection arrangement 482 may connect the first enclosure 404a to the structural frame through the second enclosure 404b, as well as optionally through any enclosures between the first enclosure and the structural frame 480, such as through a third, fourth, fifth, etc. enclosure.

[0481] The connection arrangement 482 may comprise connector, such as a rigid or flexible connector. The connector may be or comprise an elongate member. The connection arrangement 482 may be or comprise a connector rod, rope, cord, cable or the like. The connector arrangement 482 in this and previous examples may be held in tension between a connected enclosure 404 and the structural frame 480, thereby holding the connected enclosure 404 (e.g. the connected enclosure located between the floatable structure and the connection with the structural frame 480) in tension.

[0482] As previously explained, the water level 405a in the first enclosure 404a of Figure 49a is not required to be higher than the waterline 405, as the structural frame 480 is holding the first enclosure 404a in tension, and therefore there is a reduced, or no, requirement for the pressure inside the first enclosure 404a to be higher than that of the surrounding body of water, or intermediate water volume in order to hold the shape of the first enclosure 404a. Equally, this is true of the second enclosure 404b. In this example, the water level 405b of the second enclosure 404b (e.g. the intermediate water volume 415) is approximately equal to the waterline 405, although the water levels 405a, b may also be higher than the waterline 405.

[0483] In Figure 49b, the only the second enclosure 404b is connected to the structural frame 480. As is described, for example in relation to Figures 44 and 45, the first enclosure 404a may be supported by the water pressure therein, and therefore may not require any connection to the structural frame 480, provided that the water pressure inside the first enclosure 404a is higher than that of the surrounding water volume (in this case, the intermediate water volume 415, although may also be the surrounding body of water). As illustrated, the water level in the first enclosure 404a is higher than the water level in the second enclosure 404b, which may be a simple way to ensure that the water pressure inside the first enclosure 404a is higher than that of the second enclosure 404b. In this example, the water level 405a of the first enclosure 404a is higher than the waterline 405, although this need not necessarily be the case.

[0484] In the examples of Figures 49a and 49b, the structural frame 480 is connected to the floatable structure 401 (e.g. connected via a connector). The connection arrangement 482 may therefore comprise a first connector (or a first set of connectors) that connects the structural frame 480 to the fish enclosure 404 (e.g. one or both of the first and second enclosures 404a, 404b), and a second connector (or a second set of a plurality of connectors) that connect the structural frame 480 to the floatable structure 401 . The first and / or second connector (or connectors) may be flexible or rigid, and may be a cord, cable, rod, rope or the like.

[0485] According to a further example, there is a fish farming structure for a closed fish farm, comprising: a floatable structure; a closed fish enclosure configurable to be suspended from the floatable structure via a suspension arrangement; the closed fish enclosure comprising a first enclosure and a second enclosure, an enclosed intermediate water volume being defined between the first closed enclosure and the second closed enclosure, the first enclosure configured to permit fluid flow to the second enclosure so as to permit fluid communication between a water volume in the first enclosure and the intermediate water volume; and wherein the fish farming structure comprises a waste removal arrangement comprising a fluid outlet from the first closed enclosure to the second closed enclosure, and a fluid outlet from the second closed enclosure.

[0486] Illustrated in Figure 50 is an example of a fish farming structure 600 having a fish enclosure 604 the fish enclosure 604 comprising a first closed enclosure 604a and a second closed enclosure 604b (e.g. a fully-closed first enclosure and second enclosure 604a, b). Contained between the first enclosure 604a and the second enclosure 604b is an intermediate water volume 615b. The first enclosure 604a additionally comprises a fluid outlet 652, which permits water to flow from a water volume 615a in the first enclosure 604a to the intermediate water volume 615b. The second enclosure 604b comprises in this example a plurality of waste outlets 698, which permit water to exit the second enclosure, for example to an external body of water, to a vessel, to a water treatment plant, or the like.

[0487] Here, at least one of the first closed enclosure 604a and the second closed enclosure 604b may be rigid (or in cases where there are three or more closed enclosures, at least one of the enclosures, for example the innermost or outermost enclosure). Having a rigid enclosure may assist the enclosure 604 to hold its shape as water flows in the intermediate water volume 615b.

[0488] In use, water may flow from the first enclosure 604a and into the second enclosure 604b, where the water may then flow to a waste outlet where it may be removed from the fish enclosure 604. As such, the fish farming structure 600 may provide a system by which waste water may be removed from the first enclosure 604a in which fish may be located thereby improving the hygiene of the fish, and the waste water may be directed to an external or destination location, which may be variable depending on the location (e.g. depending on local legal requirements, or the like). In Figure 50, a flow path for the water flowing from the outlet 652 in the first fish enclosure 604a is illustrated by arrows. The geometry and configuration of the waste outlet may therefore comprise a circulation arrangement, where fluid flow is configured to have a desired pattern / circulation.

[0489] Although not illustrated, the first enclosure 604 may be suspended from the floatable structure 601 as previously described via a suspension arrangement. In this example, the first enclosure has a polyhedral shape, and is not connected to the illustrated structural frame 680 either directly or via a connection arrangement. As such, the water pressure inside the first enclosure 604a may assist to hold the shape of the first enclosure 604a, as has been previously described. In order to maintain the polyhedral shape of the first enclosure 604a, the material of the first enclosure 604a may be reinforced in some regions, for example edges of the polyhedral enclosure may be reinforced using a reinforcement frame, metal bar, or the like. Maintaining a higher relative water pressure in the first enclosure 604a may also assist to encourage a flow of water, and therefore establish a flowpath, through fluid outlet 652. In this example, the fish farming structure 600 comprises a structural frame 680. The illustrated second enclosure 604b, in which the first enclosure 604a is contained, is connected to the structural frame via a connection arrangement which may assist the second enclosure 604b to hold a desired shape as previously described.

[0490] At the base of the second enclosure may be located a sump 700 as in this example. The sump 700 may form part of the waste removal arrangement and / or a mort collection arrangement. The sump 700 may assist to collect particles (e.g. fish waste, fish mort, feed particles and other detritus) that settle from the water entering the second enclosure 604b via the fluid outlet 652. In this example, the second enclosure 604b comprises a lower portion in the shape of an inverted cone or pyramid, in which the sump 700 may naturally form at the base thereof (e.g. at the apex of the inverted cone or pyramid). In other examples, and depending on the geometry of the second enclosure, more than one sump 700 may form, for example in the case where the base is in the form of two or more inverted cones or pyramids.

[0491] The fluid outlet 652 directs fluid flow towards the base of the second enclosure 604b, e.g. directly at the base of the second enclosure 604b, where the sump 700 is located. The fluid outlet 652 and the positioning thereof may be considered to be or be comprised in the circulation arrangement. Directing the fluid flow in this way may assist to slow the fluid flow after flowing though the water outlet 652, thereby assisting to encourage settlement of particles in the sump 700. It should be noted that it is not necessary for the fluid outlet 652 to direct fluid flow at the sump 700, and in other examples the fluid flow may be directed at another part of the second enclosure 604b, such as a vertical wall thereof.

[0492] Located at the base of the second enclosure 604b, or the base of the sump 700 is a waste outlet 698. The waste outlet may function to remove sediment that has collected in the sump 700. The waste outlet 698 in this example is connected to a waste removal conduit 668. The waste removal conduit 668 may form part of the waste removal arrangement and / or mort collection arrangement. Although only one waste removal conduit 668 is illustrated here, there may be a plurality thereof present. The waste removal conduit 668 may deposit waste from the fish enclosure 604 in waste holding location, such as a chamber in an access structure 608, a nearby vessel, a waste processing plant, a mort container, or the like. In this example, the waste is deposited in an external location, as illustrated by the arrow 704.

[0493] Here, the waste removal conduit 668 is located externally to the second enclosure 604b, and in this example externally to the entire fish enclosure 604, although in some examples such as those where the second enclosure 604b is not the outermost enclosure, the waste removal conduit 668 may extend partially or entirely through the fish enclosure 604. The waste removal conduit 668 extends below and to the side of the fish enclosure 604, and may comprise a connection to the fish enclosure 604. Here, the waste removal conduit 668 comprises a connection to the structural frame 680, which may be by any appropriate connection means.

[0494] In order to facilitate removal of waste, the waste removal conduit 668 may comprise or be in fluid communication with a fluid propulsion means, such as a pump 702, e.g. a submersible pump, gas lift pump or the like. The fish enclosure 604, for example the second fish enclosure 604, may comprise a second waste outlet 698. The second waste outlet 698 may form part of the waste removal arrangement. The second waste outlet 698 may be located higher than the previously described first waste outlet 698. The second waste outlet 698 may be located in the side (e.g. a side wall) of the fish enclosure 604. In this example, a second waste outlet 698 is located in the fish enclosure 604 at the level of the floatable structure 601 . The second waste outlet 698 may be the surface of the intermediate fluid volume 615b, and therefore may be annular in shape and extend around the periphery of the top of the first enclosure 604a. The second waste outlet may be connected to, or in fluid communication with, a second waste removal conduit 668. The second waste removal conduit 668 may form part of the waste removal arrangement.

[0495] While the first waste removal conduit 668 may be positioned to receive sedimentary particulate waste from the fish enclosure 604, the second waste conduit may be positioned to receive waste fluids and non-sedimentary particulate waste from the fish enclosure, for example which may comprise water-soluble contaminants or particles with a neutral buoyancy in the surrounding water.

[0496] Having the first enclosure 604a positioned inside the second enclosure 604b, and the fluid outlet 652 positioned at the base of the first enclosure 604a, may create a flowpath illustrated by arrows 708 extending from the fluid outlet 652 and through the intermediate water volume 615 towards the surface of the intermediate water volume 615b, where the waste fluid may be removed by the second waste removal conduit. The intermediate water volume 615b and the flowpath 708 therein may therefore also form part of the waste removal arrangement. The inlet of the second waste conduit 668 may be positioned at the surface of the intermediate fluid volume 615b, or below the surface at the level of the collar 602, or below the level of the collar in a section of the flowpath 708 where fluid flow is substantially vertical. The second waste conduit 668 may deposit waste in an external location, which may be the external body of water, a chamber in the floatable structure 601 , a nearby vessel or processing plant, or the like.

[0497] As described in previous examples, the fish farming structure 600 comprises an inlet conduit 654. In some examples, the inlet conduit 654 may form part of the waste removal arrangement. Although one is illustrated, a plurality may be present spaced around the circumference of the structure 600. In this example, the outlet of the inlet conduit 654 is located above the water level 605 of the fish enclosure 604, and may deposit water to the fish enclosure 604 at atmospheric pressure. Water supply from the inlet conduit 654 may be used to control flow through the fluid outlet 652. For example, a constant water supply from the inlet conduit 654 may result in a constant flow of water through fluid outlet 652, while stopping the water supply may stop or reduce the flow through fluid outlet 652. The flow rate from the inlet conduit 654 may be selectively variable through use of a pump, which is illustrated in this example although other ways to selectively control fluid supply may be possible, such as by connecting the inlet conduit 654 to a supply vessel. In Figure 51 there is illustrated a fish farming structure 600 similar to that of Figure 50, although in this example the waste removal arrangement additionally comprises a waste skimmer.

[0498] The waste skimmer may comprise a gas diffusor 710, for example an air diffusor. In this example, the gas diffusor 710 is positioned in the intermediate water volume 615b. The gas diffusor 710 may be positioned inside one enclosure and outside of a second enclosure in the fish enclosure 604, for example here the gas diffusor 710 is positioned outside of the first enclosure 604a and inside the second enclosure 604b. The gas diffusor 710 may be positioned in or adjacent to (e.g. below) the flow path 708. The gas diffusor 710 may have an annular shape, and extend continuously through the enclosure in which it is positioned. In other examples, the gas diffusor 710 may extend discontinuously, and may comprise a plurality of diffusor devices positioned in a fish enclosure, here the second enclosure 604b.

[0499] The gas diffusor 710 functions to provide a stream of bubbles, in this example in the intermediate water volume 615b. The bubbles may attract organic and non-organic compounds, and remove these compounds from the intermediate water volume 615b and trap them in a foam which forms on the surface of the intermediate water volume 615. Therefore, having a gas diffusor 710 may assist to collect non-sedimentary particulate matter. Further, the bubbles may cause carbon dioxide dissolved in the water to be removed, and contained within the foam. The carbon dioxide (and other gases in the bubbles) may then be released into the atmosphere at the surface. In addition, the gas diffusor 710 may assist to stimulate fluid flow in the intermediate water volume, e.g. in the style of a gas lift pump. In this example, the gas diffusor 710 is positioned below the flow path 708 such that the bubbles transit through the flow path 708, here through a portion of the flow path 708 that extends substantially vertically. As such, the gas diffusor 710 may function to remove some compounds from the fluid in the flow path 708 before the fluid exits from the fish enclosure 604, which may improve the efficiency of the waste removal process.

[0500] Although not illustrated, it may be possible to provide a partition in the intermediate water volume 615, creating a plurality of compartments in the intermediate water volume. Each compartment may comprise its own gas diffuser, and therefore each compartment may be provided with a varying stream of bubbles (e.g. more or fewer) depending on the need in that compartment.

[0501] The fish farming structure 600 comprises a gas supply 712. The gas supply 712 may comprise a conduit which provides gas (e.g. air) from a surface location such as an air storage located on the floatable structure 601 or a vessel. The conduit may extend through the water volume in which the gas diffusor 710 is positioned, and connect to the gas diffusor 710 to provide gas thereto.

[0502] The waste skimmer may comprise a surface skimmer. The surface skimmer may be connected to or mounted on the floatable structure 601 . The surface skimmer may be or comprise a paddle, scoop, arm or the like which is configurable to be moved across the surface of a water volume (here, the intermediate water volume 615b) in order to remove waste that has collected on the surface of the water volume. The surface skimmer may comprise perforations therein. Where the waste skimmer comprises a gas diffusor 710, the surface skimmer may remove foam that has collected on the surface.

[0503] In this example, the second waste conduit 668 is illustrated as being located below the waterline 605, and may deposit fluid directly into the surrounding body of water.

[0504] In Figure 52, there is illustrated an example of a fish farming structure 600 that comprises a first and second enclosure 604a, b, wherein the first enclosure 604a does not comprise a single fluid outlet defined therein, but instead is water permeable. Therefore, the material of the first enclosure 604a itself may function as the fluid outlet. The second fish enclosure 604b in this example is not water permeable, and comprises a waste outlet 698, which may be connected to a waste conduit as previously described. In this example, larger particles such as fish mort and large feed particles, may not be able to pass through the material of the first enclosure 604a, and therefore may be collected inside the first enclosure. Meanwhile, fluid waste may pass into the second enclosure and may exit from the waste outlet 698.

[0505] Although not illustrated in Figures 49 to 52, at least one or all of the enclosures in the fish enclosure 604 may comprise fluid propulsion devices therein, such as submersible fluid pumps, which may encourage flow of water in the respective water volumes 615. This may encourage fluid flow from one enclosure to the next (e.g. from an internally located enclosure to an adjacent externally located enclosure).

[0506] In Figure 53 there is illustrated a fish farming structure 800. Although not illustrated, the fish farming structure 800 comprises many features in common with those previously described, such as a floatable structure (comprising a collar and which may comprise an access structure) and the fish enclosure 804 may be suspended from the floatable structure via a suspension arrangement.

[0507] In this example and as in previous examples, the fish enclosure 804 comprises a plurality of closed enclosures, here two enclosures 804a, 804b, and an intermediate water volume 815b located between the two enclosures 804a, b.

[0508] The fish farming structure 800 additionally comprises a temperature control arrangement or system. The temperature control system comprises a fluid inlet 914 and a fluid outlet 916. Here one fluid inlet 914 is illustrated, as are a plurality of fluid outlets 916, although in other examples there may be a plurality of inlets 914 and / or a single outlet 916. Here the inlet 914 is located at the base of the second enclosure, and the outlet 916 is located at the waterline 805, or may be below the waterline but at or above the level of the collar, for example. Fluid may flow from the inlet 914 through a flowpath 918 in the intermediate water volume 815 and out the outlet 916. The flowpath extends from the inlet 914 to the outlet 916, which here is from the base of the fish enclosure 604 to the waterline 805 or floatable structure. However, in other examples the position of the inlet and outlet 914, 916 may be varied and as such the flowpath 918 may be different to that shown.

[0509] The fluid outlets 916 may be located on the second enclosure 804b and may therefore permit flow of fluid to the surrounding body of water, or to an intermediate water volume located external to the second enclosure 804b. Additionally or alternatively, the fluid outlets 916 may be located on the first enclosure 804a, and therefore may permit fluid flow from the intermediate fluid volume 815 to the first enclosure 804a. The fluid outlets 916 may be configurable to be opened and closed, such that a user may select between flowing a fluid from the intermediate water volume 815 to either or both of the first enclosure 804a and the surrounding body of water.

[0510] A temperature control conduit 920 may be connected to the inlet 914 to provide a flow of fluid thereto. The temperature control conduit 920 may be connected to a fluid source on a vessel, the floatable structure, a nearby plant, or to the surrounding body of water. Where the temperature control conduit 920 is connected to a fluid source on a vessel, floatable structure, nearby plant or the like, the fluid source may be fluid that has been previously circulated out of the fish enclosure 804, and may therefore be a RAS system. The temperature control conduit 920 may optionally comprise a fluid propulsion means, such as a fluid pump e.g. a submersible fluid pump.

[0511] The temperature control system may additionally comprise a temperature control means for providing water of a desired temperature in the fish enclosure 804. For example, for providing water of a desired temperature in the intermediate fluid volume 815b, and / or in the water volume 815a of the first enclosure 804a.

[0512] The temperature control means may be or comprise a heat exchanger. For example a heat exchanger (or a plurality of heat exchangers) may be situated at the fluid inlet 914. The heat exchanger may be located in the temperature control conduit 920, or in the intermediate water volume 815. The heat exchanger may be used to modify the temperature of the water in the intermediate water volume 815 to a desired water temperature. The temperature of the water in the intermediate water volume 815 may then influence the temperature of the water in the first enclosure 804a, where fish may be located. The intermediate water volume 815 may function as a thermal barrier to the first enclosure 804a, meaning that it is less affected by changes in temperature of the surrounding body of water.

[0513] The temperature control means may be or comprise the temperature control conduit 920. The temperature control conduit may extend from the inlet 914 to a location in the surrounding body of water below the fish enclosure 800, for example a layer of water that has low or negligible annual temperature fluctuations. Being further from the surface, the water below the fish enclosure 800 may have a more stable water temperature, as it may be less affected by seasonal changes in air temperature, for example. As such, flowing water of a stable temperature into the intermediate water volume 815 may also stabilise the water temperature in the first enclosure 804a, which may then be more habitable for fish therein.

[0514] Having a temperature control system may be particularly beneficial in cases where a high degree of control over the water temperature is required. For example, where a RAS system is in place, the temperature of water in the system may tend toward the temperature of the surrounding body of water, particularly as no new water may be entering the system from a depth where the water temperature may be more desirable. A temperature control system may be used to prevent the water in the fish enclosure 804 from reaching the temperature of the surrounding body of water, which may be too cold or too warm, and instead a more desirable temperature may be selected.

[0515] Illustrated in Figures 54 to 57 is a fish farming structure protector 2010 for preventing damage in a fish farming structure, for example for protecting a fish enclosure and / or a floatable structure of a fish farming structure during operation thereof, such as a fish farming structure such as those previously described in relation to Figures 26 to 53.

[0516] The protection apparatus 2010 comprises an elongated buffer 2012 and connection means 2014 for connecting to a fish farming structure, for example those as previously described in relation to Figures 26 to 53. The connection means 2014 may be for connecting to a floatable structure 2101 of a fish farming structure, for example to the collar of a floatable structure 2101 .

[0517] Having protector 2010 may provide protection both to a floatable structure as well as to a fish enclosure of a fish farming structure. For example, when a fish enclosure (e.g. a closed fish enclosure, or an open fish enclosure) is raised and lowered relative to the floatable structure, the enclosure or parts thereof (e.g. the suspension arrangement) may rub or hit against the floatable structure 2101 , which can cause damage to both, especially at edges or corners of the floatable structure 2101 . This may be of particular relevance in cases where the fish enclosure comprises rigid materials, such as in the previously described examples, where the structure may comprise a rigid floatable structure. Therefore, having a protector 2010 may assist to protect the fish farming structure from damage during operation, thereby prolonging the lifespan of the structure, as well as provide a deformable contact surface for a fish enclosure and associated suspension arrangement (e.g. elongate members, cables, etc. thereof) which may also be vulnerable to damage, particularly as they may be under high tension as a result of supporting a high load.

[0518] As in this example, the elongated buffer 2012 may comprise a connection member, or a plurality of connection members, which may form part of the connection means 2014. The connection member may be a lip, flap, ridge, or the like that protrudes from the elongated buffer 2012. In this example, the connection member extends longitudinally along the elongated buffer 2012 (e.g. the entire length of the elongated buffer 2012) and is in the form of a flap that extends from the elongated buffer 2012, and may be placed flat against a structure, such as a floatable structure, for connection thereto.

[0519] The connection means 2014 may be any appropriate means for connecting the elongated buffer 2012 to a structure, such as an adhesive surface, a nut-and-bolt connection, a welded connection, a tie such as a cable, wire, rope or the like, or a vulcanised connection, for example. The connection means 2014 may cooperate with a connection profile on a structure to which it is to be connected, such as an aperture therein for receipt of a bolt or screw that may form part of the connection means 2014. The elongated buffer 2012 may be hollow, as in the example of Figure 29, or comprise a hollow 2024 therein. Having a hollow elongated buffer 2012 may reduce the weight of the elongated buffer 2012, while providing additional protection to the connected structure (e.g. the floatable structure) in cases where the elongated buffer 2012 itself deforms. Rather than causing damage to the connected structure, the elongated buffer may simply deform into the hollow space therein.

[0520] The protector 2010 may be made from single piece or section of material, although a protector 2010 made from multiple sections of material may also be possible. The protector 2010 may be made from a flexible material, such as a flexible plastic. The material of the protector 2010 may be an elastic material, such as a rubber material.

[0521] The elongated buffer 2012 may be flexible. The elongated buffer 2012 may be inflatable. The elongated buffer 2012 may comprise an air pocket 2022 therein, or a plurality of air pockets 2022 therein. The air pocket 2022, or plurality of air pockets, in the elongated buffer may be inflatable with a gas such as air. The air pocket 2022, or plurality of air pockets, may be located or define a wall cavity in the protector, for example in the elongated buffer 2012 of the protector 2010, and / or in the connection means 2014. Having an inflatable elongated buffer 2012 may permit the buffer to provide a cushioning effect, by providing a cushion of air between the structure and an external object, such as a fish enclosure, cables, or the like. The elongated buffer 2012 may comprise one air pocket, or a plurality of air pockets. The plurality of air pockets may extend along the length thereof and may be circumferentially and / or longitudinally spaced from one another. The plurality of air pockets may optionally be able to be expanded and contracted by inflation (e.g. if the protector 2010 is made from a plastic and / or elastic material).

[0522] The elongated buffer 2012 of Figure 54 is illustrated as being open at an end thereof. However, it should be noted that in some examples the elongated buffer may be closed at the ends thereof, and / or at the ends of the or each hollow 2024 thereof, such that the hollow 2024 is an enclosed volume between the elongated buffer 2012 and an external structure 2101 , such as the corner of an external structure 2101 .

[0523] The elongated buffer 2012 may comprise a curved surface, to minimise damage on an object with which it is brought into contact, such as a fish enclosure, a cable or the like, by minimising point loads on the object, and friction between the buffer 2012 and the object. The exterior surface of the buffer 2012 may be curved for this purpose.

[0524] The protector 2010 may connect to a first and a second surface 2018, 2020 of a structure, such as a floatable structure. The first surface 2018 may be non-parallel to the second surface 2020. The first surface 2018 may be obliquely orientated relative to the second surface 2020. The first surface 2018 may be perpendicular to the second surface 2020. As such, the protector 2010 may be configured to be located at, and over, and edge or corner of a structure. The protector 2010 may therefore cover and offer protection to both the first and the second surface 2018, 2020.

[0525] Illustrated in Figure 55, a fish enclosure or a suspension arrangement of the fish enclosure 2104 may be connected to the protector 2010 itself, or may be located adjacent the protector 2010. Where the fish enclosure or suspension arrangement 2104 is connected to the protector 2010, the protector may comprise an enclosure connection means 2016, such as a rib, flange, protrusion or the like that extends therefrom. The enclosure connection means may comprise a connection profile such as an aperture, a hook, a protrusion, an adhesive surface or the like for connection of a fish enclosure thereto. In both cases in Figure 55, it is illustrated that the fish enclosure or suspension arrangement 2104 is held apart from the structure 2101 via the protector 2010.

[0526] Figures 56 and 57 illustrate a second example of a protector 2010. In this example, the protector 2010 also comprises an elongate buffer 2012 and a connection means 2014, which may be similar to those as previously described. In contrast, the protector 2010 of Figures 56 and 57 does not comprise any air pockets, although comprises a hollow 2024, or in the example of Figure 57, a plurality of hollows therein. In the example of Figures 56 and 57, the protector 2010 may be made from rubber, and therefore may be sufficiently stiff to hold its shape without the requirement of air pockets, while still comprising a degree of flexibility such that it is able to elastically deform upon contact with an external object, such as a fish enclosure, suspension arrangement, or the like. As with the previous example, the protector 2010 extends across a first surface 2018 and a second surface 2020, thereby covering the surface and offering protection thereto.

[0527] As in the previous example, the connection means 2014 may be any appropriate means for connecting the elongated buffer 2012 to a structure, such as an adhesive surface, a nut-and-bolt connection, a welded connection, a tie such as a cable, wire, rope or the like, or a vulcanised connection. The connection means 2014 may cooperate with a connection profile on a structure to which it is to be connected, such as an aperture therein for receipt of a bolt or screw that may form part of the connection means 2014.

[0528] As was also illustrated in Figure 55, a fish enclosure or a suspension arrangement of the fish enclosure 2104 may be connected to the protector 2010 of Figure 57 itself, or may be located adjacent the protector 2010. Where the fish enclosure or suspension arrangement 2104 is connected to the protector 2010, the protector may comprise an enclosure connection means 2016, such as a rib, flange, protrusion or the like that extends therefrom. The enclosure connection means may comprise a connection profile such as an aperture, a hook, a protrusion, an adhesive surface or the like for connection of a fish enclosure thereto. In both cases in Figure 30, it is illustrated that the fish enclosure or suspension arrangement 2104 is held apart from the structure 2101 via the protector 2010.

[0529] Another aspect of the present disclosure relates to an improved utility structure for fish farm and method for providing utility to fish farm. According to an example embodiment there is provided a utility structure for a fish farm, the utility structure comprising: a turret configurable to be moored at an offshore location, and being rotatably connected to a supply structure such that the supply structure is rotatable about a central axis of the turret; the supply structure comprising a utility storage and a utility transfer arrangement for transferring a utility between the turret and the supply structure, and the turret comprising a utility connection for transfer of a utility between a fish farm and the turret.

[0530] In use, the utility structure may be moored in a body of water, and may be connected to a fish farm (or a plurality of fish farms) via a utility connection to enable a utility to be transferred between the utility structure and the fish farm. A turret of the utility structure may be moored (e.g. anchored) in a desired location, and the utility connection between the turret and the fish farm established. Utilities may be supplied to the turret by a utility transfer arrangement, for example from a utility storage of a supply structure connected to the turret. Once moored in a location, the supply structure rotates about a central axis of the turret. This may have the effect of shielding the supply structure, or parts of the supply structure, from harsh weather conditions, such as strong winds or large waves, as the supply structure may naturally align itself to the orientation of least resistance against weather conditions. This is particularly relevant at exposed or offshore locations. When used in combination with a fish farm, the utility structure may assist to encourage a flow of water through the fish farm by rotating to have minimal impact on fluid flow in the vicinity of the fish farm, thereby not blocking or disrupting a fluid flow though the fish farm, as may be the case with a utility structure that is moored in the vicinity of a fish farm and is unable to rotate. The described utility structure may therefore assist to improve the welfare of the fish in the fish farm by increasing the flow of water through the fish farm, which may increase the overall oxygenation of water in the fish farm, and improve hygiene in the fish farm by sweeping away waste, detritus and other contaminants that may otherwise build up within the fish farm. Further, having a fish farm connected to a moored turret may facilitate a faster connection and disconnection between the fish farm and the utility structure (e.g. of the utility connection between the fish farm and the turret), thereby reducing the likelihood of both the fish farm and the utility structure sustaining damage, or indeed causing damage to one another.

[0531] In Figures 58a-c there is schematically illustrated a plan view of two examples of a utility structure 3010, 3210. The utility structure 3010, 3210 may be a vessel such as a self-propelled vessel, or may be a towable vessel. The vessel may be in the form of a ship or a barge.

[0532] In the example of Figure 58a, the utility structure comprises a turret 3012 which is rotatably connected to a supply structure 3014, such that the supply structure 3014 is able to rotate about a central axis of the turret 3012. In this example, the turret has a generally cylindrical shape, although in other examples may have an alternative shape, such as a frustum cone. The turret 3012 may have a constant horizontal cross-sectional shape. For example, the turret 3012 may have a circular cross- sectional shape along the length of the turret 3012, which may optionally vary in diameter. The central axis of the turret 3012 is the longitudinal axis 3038 (see Figure 60) in this example. The turret 3012 is in this example located within the supply structure 3014. The turret 3012 may be laterally surrounded by the supply structure 3014. A section of the turret may be fully laterally enclosed (e.g. surrounded in 360 degrees) by the supply structure 3014. Such a connection between the turret 3012 and the supply structure 3014 may be extremely stable, and may reduce the risk of disruption or damage to communications and materials supply between the turret 3012 and the supply structure 3014.

[0533] Here, the utility structure 3010 is in the form of a vessel (e.g. a utility vessel) and is located in a body of water, which may be an exposed and / or offshore location such as in the open sea or ocean. To hold the utility structure 3010 in position in the body of water, a plurality of mooring lines are attached to the turret 3012. The plurality of mooring lines 3018 may hold the turret stationary (e.g. geostationary, relative to the seabed), or restrict movement (e.g. lateral movement) of the turret 3012 in the body of water, while permitting a degree of longitudinal movement of the turret (e.g. movement aligned in the direction with the longitudinal axis of the turret 3012).

[0534] Being rotatably connected to the turret 3012, the supply structure 3014 is permitted to rotate about the longitudinal axis 3015 of the turret, in the direction of the arrow 3016 shown in Figure 58a. The supply structure 3014 may be permitted to freely rotate about the turret 3012, for example the movement of the supply structure 3014 relative to the turret 3012 may be solely based on environmental forces, and rotation about the central axis of the turret 3012 may not be restricted by the turret 3012 or supply structure 3014. The supply structure 3014 may be able to rotate by a significant angle (e.g. not a small angle) relative to the turret 3012, for example 90, 180, 270 and 360 degree rotation of the supply structure 3014 relative to the turret 3012 may be permitted. As illustrated in Figure 58a, the supply structure may illustrate between the position shown, and the outlined position. The supply structure 3014 may be able to rotate fully around the turret 3012 - i.e. rotate through 360 degrees around the turret 3012 and may be able to rotate multiple times and / or indefinitely around the turret 3012. The supply structure 3014 may be passively rotatably connected to the turret 3012. As such, the supply structure 3014 may be able to weathervane around the turret 3012. The supply structure 3014 may rotate around the turret 3012 due to external forces acting on the supply structure 3014, for example external weather forces such as wind forces or wave forces. The supply structure 3014 may naturally rotate around the turret 3012 such that the longitudinal axis 3020 is aligned with (e.g. parallel with) the prevailing weather direction (e.g. at least one of the prevailing wind and / or wave direction). The utility structure may comprise active heading control of the rotation of the supply structure 3014 around the turret 3012, for example via a control system. The supply structure 3014 may comprise a control arrangement of at least one of thrusters, rudders or other means for active heading control e.g. to avoid excessive roll motion if wind and wave directions are not colinear. It may also be possible to temporarily prevent (e.g. lock) rotation between the turret 3012 and the supply structure 3014 e.g. in benign weather conditions to perform sporadic / periodic loading / offloading operations between turret and supply structure.

[0535] As will be described in more detail in reference to the following figures, a utility transfer arrangement (not illustrated in Figure 58a) for supplying the turret 3012 with a utility from the supply structure 3014 may extend between the turret 3012 and the supply structure 3014. For example, the utility transfer arrangement may comprise at least one fluid conduit for fluidly connecting the turret 3012 to the supply structure 3014 (e.g. a feed or water supply conduit) and / or may comprise at least one cable for electrically and / or fibre-optically connecting the turret 3012 to the supply structure 3014 (e.g. an electrical and / or fibre-optical cable for providing control and / or electrical power to the turret 3012). All critical equipment for operation of a fish farm may be located on the turret 3012, thereby meaning that a temporary disconnection of the turret 3012 from the supply structure 3014 will not affect short-term operation of the fish farm. The turret 3012 may also comprise a storage (e.g. a secondary or backup storage) of fish feed. The utility transfer arrangement may comprise corrosion resistant material for protection against corrosive fluids being transferred between the turret 3012 and supply structure 3014. For example, conduits extending between the turret 3012 and the supply structure 3014 may comprise a corrosion resistant material, such as 25CrDuplex or Titanium. Having a utility structure comprising a turret and a supply structure may limit the amount of corrosion resistant material that is required, for example by permitting the transfer of dry substances which may be less corrosive, as will be described. As such, the described systems provide the user with a means for cost savings as compared to known systems.

[0536] To facilitate connection between the turret 3012 and the supply structure 3014, as well as transfer of utilities therebetween, the utility structure 3010 may comprise a swivel arrangement such as a swivel pipe connection or a swivel stack. The swivel arrangement may permit rotation of the supply structure 3014 relative to the turret 3012 without disconnection of a connection (e.g. a utility connection) therebetween. The swivel arrangement may be located at the top of the turret 3012, for example on the uppermost deck of the turret 3012. The swivel arrangement may be an electrical swivel, comprising a rotatable electrical connection between the supply structure 3014 and the turret 3012, and / or may be a fluid swivel, compr...

Claims

CLAIMS1. A fish farming system, comprising a floatable structure comprising a collar and an access structure which is floating on a body of water; the collar defining an access opening therein for providing access to the fish enclosure, and the collar being submerged in the body of water, the access structure connected to the collar, and extending from a submerged location at which the access structure connects to the collar, to a location above a waterline of the body of water, characterised in that the system further includes a fish enclosure containing fish which is suspended from the floatable structure via a suspension arrangement so that an uppermost portion of the fish enclosure is spaced from a lowermost edge of the floatable structure.

2. A fish farming system according to claim 1 further comprising a hang-off support which is mounted on the floatable structure, the suspension arrangement comprising an elongate element and a stop, the elongate element extending from the fish enclosure to the stop, the stop engaging with the hang-off support so that the fish enclosure is supported by the hang-off support via the stop and the elongate element, so that the uppermost portion of the fish enclosure is spaced from the lowermost edge of the floatable structure.

3. The fish farming system of claim 1 or 2, further comprising a height adjustment apparartus located on at least one of the access structure and the suspension arrangement, the height adjustment apparatus being operable to raise and lower the fish enclosure relative to the floatable structure.

4. The fish farming system of claims 2 and 3, wherein the suspension arrangement comprises a further elongate element which extends from the stop to the height adjustment apparatus.

5. The fish farming system of claim 3, wherein the height adjustment means comprises an elongate member which extends from the access structure to the fish enclosure.

6. The fish farming system of any preceding claim, wherein the fish enclosure comprises at least one of an upper structure and a lower structure.

7. The fish farming system of any preceding claim, wherein the fish enclosure comprises both an upper structure and a lower structure.

8. The fish farming system of any preceding claim, wherein the fish enclosure comprises a weighted frame and an air pocket.

9. The fish farming system of claims 7 and 8, wherein the air pocket is housed in the upper structure and the weighted frame is defined by the lower structure.

10. The fish farming system of any preceding claim, wherein the collar has a polygonal vertical cross-section.11 . The fish farming system of any preceding claim, wherein the collar has a rectangular vertical cross-section.

12. The fish farming system of any preceding claim, wherein the collar comprises a collar extension in the form of a heave plate connected thereto.

13. The fish farming system of any preceding claim, wherein the suspension arrangement extends from the access structure to the enclosure.

14. The fish farming system of claim 13, wherein the suspension arrangement comprises a flexible elongate member that extends between the floatable structure and the fish enclosure.

15. The fish farming system of claim 3 and any preceding claim which is dependent on claim 3, wherein the height adjustment means comprises a connector to a winch, and is selectively operable by a user.

16. The fish farming system of any preceding claim, wherein the access structure comprises a plurality of discreet columns extending from the collar, each of the discreet columns configurable to extend from a submerged point of contact with the collar to a location above the waterline.

17. The fish farming system of any preceding claim, wherein the hang-off support is located at the base of the collar.

18. The fish farming system of claim 17, wherein the stop comprises a plug and the hang-off support comprises a restrictor having a seat for the plug, wherein when the plug is seated in the restrictor, and movement of the suspension arrangement relative to the collar is restricted.

19. The fish farming system of any preceding claim, wherein the collar has a polygonal horizontal cross-section, and comprises an access structure at each corner thereof.

20. The fish farming system of claim 19, wherein the collar has a rectangular horizontal cross-section, and comprises an access structure at each corner thereof.21 . The fish farming system of any preceding claim, comprising a plurality of access structures, each of the plurality of access structures being located radially inwardly of the collar.

22. The fish farming system of any preceding claim, wherein the fish enclosure comprises access to a source of feed.

23. The fish farming system of any preceding claim, comprising an access column extending between the access structure and the fish enclosure.

24. The fish farming system of any preceding claim, wherein the collar comprises a lice skirt.

25. The fish farming system of claim 24, wherein the lice skirt is at least partially supported by the access structure, and is configurable to extend above a waterline.

26. A method for operation of a fish farming system, comprising: providing a floatable structure, comprising a collar and an access structure located on the collar, in a body of water; submerging the collar below a waterline in the body of water such that the access structure extends between a submerged point of contact with the collar and a location above the waterline of the body of water; suspending a fish enclosure containing fish from the floatable structure via a suspension arrangement so that an uppermost portion of the fish enclosure is suspended below and spaced from a lowermost edge of the floatable structure; providing access to the fish enclosure through the collar via a central recess defined in the collar.

27. The method of claim 26 wherein the system comprises a hang off support mounted on the floatable structure, and the suspension arrangement comprises an elongate element and a stop, the elongate element extending from the fish enclosure to the stop, and the method comprises suspending the fish enclosure from the floatable structure by engaging the stop with the hang-off support.

28. The method of claim 26 or 27, comprising, prior to placing fish in the fish enclosure, connecting the fish farming system to a vessel, and towing the fish farming system to a desired location in a body of water.

29. The method of claim 26, 27, or 28, comprising, prior to placing fish in the fish enclosure, installing the fish farming system in a body of water via a crane on a vessel.

30. The method of any of claims 26 to 29, wherein the fish farming system further comprises a height adjustment apparartus located on at least one of the access structure and the suspension arrangement, the height adjustment apparatus being operable to raise and lower the fish enclosure relative to the floatable structure, the method comprising carrying out a service operation by using the height adjustment apparatus temporarily to lift the fish enclosure at least partially above the waterline.

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