Fish cage

Abstract

The invention is related to a fish cage comprising a net pen 1, walkways 2 and at least three legs 3. The legs 3 are arranged to be mounted on the sea bed 4 and the walkways 2 are arranged between the legs 3. The net pen 1 is attached to each legs 3 at two or more different attachment points 5, and the legs 3 are arranged to keep the net pen expanded.

Description

[0001] Fish cage

[0002] The present invention is related to a fish cage, designed to be used in exposed locations, according to the preamble of the independent claims.

[0003] Background

[0004] Aquaculture is one of the fastest growing food producing sectors, and is forecasted to grow between to between 102-105 million tonnes by 2027, according to OECD and FAO outlooks. Suitable new locations for inshore production are limited, and the production of fish may have to move to offshore locations. Offshore locations will offer good water quality, steady ocean currents, and low variance in temperature which will give optimal growing conditions, reduce the probability of diseases and parasite infestations as well as improving the general fish health.

[0005] In Norway, construction and strength of offshore plants, and aquaculture cages and plants in general, are regulated by the authorities. Further, it is not allowed to grow aquatic animals in the sea without approval of the cage and allowance for use of the localisation. Therefore, any new fish cage must also be made in accordance with these regulations.

[0006] A fish farming plant typically comprises several aquaculture cages and they may have a common barge, wherein feed and common equipment are arranged. The aquaculture cages may be net cages, closed cages or semi closed cages. The choice of cage depends on the location site and the preferences of the fish farmer.

[0007] A traditional fish cage is an open cage comprising a floating collar at the surface of the sea, a net bag fastened to the collar and surrounding the farmed organisms, and weights to keep the net bag expanded and in shape. The bag may be made of a net or a similar material having meshes, and the weight will expand the bag in such a way that the meshes are open. The water surrounding the net bag will flow in and out of the net, ensuring a healthy environment to the fish in the net bag. An object of the invention is to provide a fish cage being suitable for localization offshore, meaning that it should be designed to withstand increased wave height, stronger currents and interaction with larger vessels than cages suitable for inshore localization.

[0008] Another object is that the cage should ensure no escape of the farmed organisms, and it should be possible to maintain and control the cage remotely, to ensure the security of the staff. Yet another object is that the cage should be sustainable and commercially viable. Finally, the cage should be designed according to all regulations and demands.

[0009] The invention

[0010] The objects are met by a fish cage according to the characterizing part of the independent claims. Further advantageous details are stated in the dependent claims.

[0011] The invention is related to a fish cage comprising a net pen, walkways and at least three legs, wherein the legs are arranged to be mounted on the sea bed. The walkways are arranged between the legs, and attached to the legs, leaving an exposed side or axial area of each leg facing towards the net pen. The net pen is attached to the exposed side or axial area of each leg at two or more separate attachment points of the net, and the legs are arranged to keep the net pen expanded.

[0012] The legs may be provided with means for fastening to the sea bed, such as suction anchors, spud can footings or the similar which will secure the legs to the sea bed. The two or more separate attachment points of the net pen being attached to each leg, may preferably be at two opposite parts of the net pen. By “opposite parts of the net pen” it is herein meant one attachment point at an upper part and one attachment point at a lower part when the fish cage is installed in water. Two separate attachment points should be attached to each leg, meaning that the net pen will be attached both at an upper part and at a lower part of the same leg. The net pen may comprise further attachment points and be attached to a leg at any places, even between the upper and lower part. This means that if the fish cage comprises 3 legs, the net pen will be attached to the legs at least in 6 different places, and if the fish cage comprises 4 legs, the net pen will be attached at least in 8 different places etc. Each attachment points should be attached at one or more places of the leg, preferably each attachment point is attached to a separate place of the leg. The points should however be on the same side of the leg, preferably along a line, in such a way that all fastening points will be above each other when the net pen is installed in water.

[0013] The attachment points of the net pen may be strengthen parts of the net pen, or a part of the net pen already strengthen may be used as an attachment point. The attachment points must withstand all forces acting on the net pen without breaking or unfasten from the leg and without damaging the net pen.

[0014] The net pen is preferably attached to the legs by ropes, lines, wires, chains or the similar, running from the separate attachment points of the net pen to the legs. By attaching the net pen in this way, a distance between the net pen and the leg is created, and possible damage to the net pen as a result of contact between the legs and the net pen is reduced. Further, the attachments will contribute to holding the net pen expanded.

[0015] The net pen may be any bag suitable for keeping the fish inside the bag, and may be closed, open or semi-open. When the net pen is “open” it should be understood that the net pen is at the least partly made of a net having meshes wherethrough the water can flow. The net pen may comprise any equipment regularly used at fish cages, such as equipment to keep it expanded for instance weights, sinker tubes, stiffening rings or the similar.

[0016] The legs are arranged to keep the net pen expanded, and if the net pen is made of a net having a given mesh width, the fastening to and arrangement of the legs will keep the mesh expanded. When the mesh is expanded, water may flow in and out of the net pen, keeping the environment inside the net pen healthy. If the fish cage comprises three legs, they may be arranged as a triangle, if the fish cage comprises four legs, they may be arranged as rectangle, trapezoid, parallelogram etc depending on the shape of the net pen. The fish cage may also comprise 5, 6 or even more legs, depending on the localization of the fish cage.

[0017] The fastening of the net pen to the legs may be the only fastening to keep the net pen in place, and to keep the net pen expanded. In this way the net pen and walkways may be moved in relation to each other without having to release the fastening of the net pen.

[0018] The walkways are arranged between the legs, and may be arranged above or at the surface of the sea, once the fish cage is installed in the sea. The walkways will thus be above the net pen when the net pen is in the sea. When the cage comprises three legs, the cage may comprise two walkways respectively arranged between a first and second leg, and between the second and a third leg. Similarly, when the cage comprises four legs, the cage may comprise three walkways respectively arranged between the first and second legs, second and third legs, and third and fourth legs. The cage may comprise the same number of walkways as the number of legs, each walkway arranged between two legs. The cage may comprise more walkways than legs, as walkways may be arranged between legs crosswise of the cage, such as diagonally when the legs are arranged as a square or rectangle.

[0019] The walkway may be provided as one part having the desired shape, or as several parts being connected to each other and / or to the legs. The walkway may of course also be provided as one larger part, for instance a triangle to run between three legs, and in addition more parts to be arranged diagonally of the cage or any other combination of parts.

[0020] The walkways may support the legs, and reinforce the cage. When the legs are only fastened to the sea bed, the upper end of the legs may move in relation to each other, for instance due to waves and wind. The walkways will strengthen the integrity of the construction and prevent such movement as the cage will appear as a more rigid construction.

[0021] By arranging the net pen, legs and walkways of the fish cage as described above, the fish cage will become very rigid and strong, and may be used in exposed locations even offshore.

[0022] The walkways are configured to provide access for staff to area between the legs. The walkways may therefore be provided with a walking path and handrail, and possibly space for mounting and / or storing other equipment normally used during farming, such as winches, bird nets, pipes for removal of fish, system for removal of dead fish. Equipment related to feeding, such as feed and feed pipes, may also be arranged on the walkways. Further, in addition to walkways there may be a deck that is fastened at the an upper part of the legs, and any equipment may also be stored on the deck. The deck may further comprise living quarters, labs, storage rooms etc. similar to the deck of an oil drilling platform.

[0023] The walkways may be provided with buoyancy elements, either being integrated in the walkway, or separate elements being fastened to the walkway. The buoyancy may be sufficient to carry the weight of the whole fish cage. When the fish cage is being transported to the site for installation, the walkways may keep the fish cage floating, and the cage may be towed by a boat. This is an advantage as the cage may be mounted on shore.

[0024] The walkways and legs may be moved in relation to each other, by moving the walkway along the length of the legs, that is vertically once the cage is installed, and each leg may be moved individually. The legs may thus be lowered until they are installed at the sea bed. Further, the legs may be lowered individually and differently, keeping the walkways horizontal, even if the seabed is slanting. During transportation to the installation site, the legs may be raised partly or fully above the walkways and the fish cage may be towed across shallow areas without any risk of running aground. After installation, for instance in case of strong wind and / or big waves, the walkways may be raised to avoid being hit by the waves, and thus the walkways themselves, and any equipment installed on the walkways, will be protected.

[0025] The walkways may be attached to sides of the legs, preferably leaving an exposed side or axial area of the leg facing towards the net pen. For instance, if each leg has three sides, meaning that the legs have a triangular cross section, the walkways may be adjacent or attached to two sides. The third side may be exposed, meaning that is not covered by the walkways, or have at least one axial exposed area, meaning an area in axial direction of the leg, which is not covered by the walkways. Further, if the legs have four sides, the walkway may be adjacent or attached to three sides etc. If the legs have a round or circular cross section, the walkways may be adjacent or attached to the legs around parts of the circumference, such as around 180, 270 or even 300 degrees. The remaining part will then be the exposed side of the leg. Axial direction is along the length of the leg, being vertical once the fish cage is installed in the sea.

[0026] The net pen should be attached to each leg on the exposed side, or in the exposed areas, and thereby the net pen may be moved along the legs regardless of the attachment to the walkways. In case each leg has one exposed axial area, the area should be sufficiently large to allow attachments of the net pen, and to allow the net pen to be raised and / or lowered the desired distance. In case each leg has several exposed axial areas, the net pen may be attached to the leg in different areas, and each area should be sufficiently large to allow attachment of the net pen, and to allow the net pen to be raised and / or lowered the desired distance.

[0027] The attachment of the net pen to each leg, and the exposed side or area(s) of each leg may be arranged to allow the net pen to be raised above the walkways. Thereby it will be possible to transport the fish cage over shallow water even when the net pen is installed. Further it will be possible stand on the walkway and perform service on the net pen. Walkways arranged crosswise of the cage as described above, may be arranged pivotally, foldable, tiltable or the similar, in order to allow the net pen to be raised above the walkways.

[0028] The walkways may be attached to the legs by a rack and pinion system. A rack may be included in the legs, and a pinon may be arranged on the walkway. As the pinon is moved along the rack, the walkway will be lowered or raised as desired. The pinon may be controlled and powered from a suitable unit arranged on the walkway.

[0029] The walkways may be attached to the legs by a system of locking pin actuators and locking holes. A row of locking holes may be included in the legs, and locking pin actuators may be arranged on the walkways. A locking pin actuator comprises an extendable cylinder having an upper locking pin at one end, and a lower locking pin at the opposite end. The locking pin actuator is configured to insert an upper locking pin into a locking hole, then release the lower locking pin and retract the cylinder, then insert the lower locking pin, release the upper locking pin and expand the cylinder again. This will continue until the walkway is at the desired position. The actuators may be controlled and powered from a suitable unit arranged on the walkway.

[0030] The legs may be made of any suitable material, being sufficiently strong to carry the fish cage, and to withstand the harsh environments at the localization. The legs may be girders such as H-beams, also known as differdings.

[0031] The legs may have be hollow, meaning that they have an axial inner space, and any cables, pipes, ropes, wires, lines or the similar may be arranged inside the legs. Said cables, pipes, ropes, wires, lines etc may be running from the walkways to the net cage. The legs may be made of a hollow pipe or truss framework. Each leg may for instance be made of several sides connected to each other to create a leg having an axial space, and each side may be made of truss framework. In this way the legs may be light but still being sufficiently strong to carry the weight of the whole fish cage, and sufficiently rigid to withstand any forces acting on it. By having hollow legs or legs having an axial inner space, and by arranging the cables, pipes, ropes, wires, lines etc inside the legs, the cables, pipes, ropes, wires, lines etc will be protected from the harsh environment at the localization and wear and tear will be reduced. Further, when the legs are made of hollow pipes or truss framework, the weight will be substantially reduced, which will be an advantage at installation and transportation.

[0032] As described above, the net pen is attached to each leg at least at two different attachment points of the net pen. The net pen may be attached to the leg in such a way that the net pen may be moved in relation to the legs. The net pen may be attached to the legs by ropes, lines, straps, cables and the similar, and possibly by hoist trolleys. “Hoist trolleys” should be understood to include all devices which can be moved along the legs, preferably having a wheel or roller running along the leg. The legs may comprise a rail wherein the hoist trolleys are fastened.

[0033] At least one hoist trolley on each leg may be automotive, possibly controlled and powered from the walkways. The other trolley or trolleys on the same leg may be passive, or automotive. In one embodiment the uppermost and lowermost trolley may be automotive to ensure movement of the net pen in the desired direction, without risking too much tension in the net pen.

[0034] When the net pen is attached to the legs by hoist trolleys, the net pen may be submerged as a response to threats on the surface, such as algae or lice, or raised for maintenance, easy access to the net pen or the similar. The net pen may of course also be lowered and / or raised in response to weather and wave conditions to avoid damage to the net pen.

[0035] At least one hoist trolley on each leg may be connected to a winch preferably arranged on the walkway. The winch may be connected to automotive hoist trolleys as security, and / or the passive trolleys to ease the lowering / raising. In case no trolleys are automotive, the winches will be controlling the movement of the net bag. The operation of the winches must be regulated both according to desired movement of the net pen, but also according to any movement of the walkway, to ensure that the movement of the walkway does not influence the position of the net pen.

[0036] In embodiments described above, wherein the walkways are fastened to the legs leaving a side or axial area exposed, the hoist trolleys should be fastened to the legs on this side. Thereby the net pen may be moved along the legs, regardless of the position of the walkways. In case the net pen should be hoisted above the surface of the sea, and the walkways are arranged at the surface of the sea, the hoist trolleys will pass the walkways. In case the hoist trolleys are operated by winches on the walkway, the winch must then either be arranged somewhere else, or a wire of the winch may be arranged via a pulley or castor on an upper part of the leg.

[0037] The net pen may alternatively or in addition to the hoist trolleys be attached to the leg by a pulley or block system arranged between the attachment point of the net pen and the leg . By “pulley” it is herein meant blocks, sheaves, tackles and the similar. A pul ly may be arranged between the net pen and a hoist trolly, to regulate the distance between the net pen and the leg to which it is attached. When pullies are arranged at all attachments, the net pen may be moved horizontally between the legs. The pullies may be arranged singular and / or in series at each attachment between the net pen and the leg.

[0038] Upon maintenance of the net pen, or when access to the organisms in the net pen is desired, the net pen may be raised to a suitable height, and / or the height of the walkway may be adjusted until convenient distance from walkway to net pen is achieved. The staff may walk on the walkway, and as the walkway is arranged between the legs, staff will have full access to the circumference of the net pen. Further, if the net pen is attached to the legs by pullies, the net pen may be pulled closer to the walkway if desired.

[0039] A net and / or an impermeable material may be fastened to and arranged above the net pen, to form a roof or top cover of the net pen. In case the net pen is submerged below the surface of the sea, a roof is needed to prevent the organisms leaving the net pen. In case an impermeable material is used, air may be entrapped under the material to give the organisms access to air. Use of impermeable material as roof of a submerged fish cage and entrapped air is well known to a skilled person. Whether a net, an impermeable material or a combination is preferred, depends inter alia on how long and how often the net pen should be submerged and the needs of the organisms being in the net pen.

[0040] The fish cage may comprise lights, sensors, cameras and similar equipment regularly used during farming of aquatic animals. Such equipment may be arranged in or at the legs. The fish cage may further comprise well-known devices for fish farming, including systems for feeding, for removal of dead fish and sludge, and for monitoring water quality among others. Any pipes, hoses, cables etc needed for such systems may also be partly or fully arranged in or at the legs, and as described above, they will be protected from the environment. Depending on for instance the type of net pen, the localization and the fish trait to be farmed, the fish cage may also comprise pumps for adding and / or circulating water into the net pen, and possibly devices for adding air or oxygen to the water while removing any undesired substances. These systems are all well-known to a skilled person.

[0041] The fish cage may further comprise a transmitter and a receiver for signals remotely, and / or an onshore power and network cable to enable monitoring and control onshore. The control should both relate to feeding etc as is well known in relation to fish cages, but also to movement of the walkway and net pen.

[0042] Several fish cages according to the present invention may be arranged adjacent each other, whereby walkways from several fish cages may be fastened to the same leg, and whereby one walkway may give access to several fish cages. For instance two fish cages may be arranged side by side, having six legs and six walkways, or four fish cages may be arranged in a square, having nine legs and 12 walkways. A common housing for equipment, storage, feed, control room etc may be arranged between the fish cages. The fish cage according to the invention may be used to breed any aquatic animals, preferably fish such as salmonids or cod, more preferably salmon or trout.

[0043] The invention will in the following be described by way of exemplary embodiments and accompanying drawings. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. The following embodiments are discussed, for simplicity, with regard to an open net pen for fish typically deployed in the sea. However, it should be appreciated that the fish cage is also applicable and suitable for use in respect of breeding any other aquatic animal.

[0044] Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment.

[0045] In the description relative terms such as front, top, centre, bottom, side, lower, upper, downward, upward, outward, sideward, vertical, and horizontal etc. are all related to the device when in upright position i.e. when mounted in a fish cage ready for use.

[0046] Examples

[0047] Embodiments of the present invention will now be described, with reference to the following schematic figures wherein:

[0048] Figure 1 shows a fish cage according to the invention, wherein the net pen is submerged in the sea,

[0049] Figure 2 shows details of the attachment between the net pen and a leg, Figure 3 shows a cross section of through the walkway of the fish cage, Figure 4 shows the fish cage of Figure 1 , wherein both the legs and the fish cage are elevated above the walkway being on the surface of the sea, and Figure 5 shows the fish cage of Figure 1 , wherein the net pen is elevated above the walkway being on the surface of the sea.

[0050] The Figures are given for illustrative purposes only, and therefore the different parts of the Figures are not necessarily to scale in relation to each other.

[0051] Figure 1 shows a fish cage according to the invention, having a net pen 1 , walkways 2 and three legs 3. The legs are mounted on the sea bed 4, by an anchor (not shown), and the walkways 2 are arranged between the legs 3, creating a triangle. The net pen is shown submerged in the water, and a top cover 8 of net is arranged over the net pen, creating a roof of the cage and preventing fish from swimming out of the net pen. In the shown embodiment, the walkways are arranged at the surface of the sea 6, and a person 7 is indicated on the walkway.

[0052] Figures 2 and 3 show the attachments between the net pen 1 and a leg 3 and between the walkway 2 and the leg 3, in detail. Figure 2 shows fish cage from the side, and Figure 3 shows a cross section through the walkway 2 of the fish cage.

[0053] In the shown embodiment each leg 3 has three sides 3a, 3b, 3c connected to a triangle, and each side is made of truss framework. In this way the legs are light but very strong and rigid. Two of the sides 3a, 3b of each leg are adjacent to the walkways 2, and the third side 3c of the leg, facing the net pen, is provided with a rail 9.

[0054] Two hoist trolleys 10 are attached to, and arranged to be running along the rail 9. The trolleys are connected to the attachment points 5 of the net pen 1 by wires 11 , creating a distance between the net pen and the legs. This distance is not shown in Figures 1 , 4 and 5 for clarity reasons.

[0055] By adjusting the position of the hoist trolleys 10 along the rail 9, the vertical position of the net pen 1 may be adjusted. The net pen may be submerged, at the surface of the water or above the surface of the water as a response to different circumstances. In the figures the shown hoist trolleys are connected to a winch 12 by a winch wire 13, and the winch is arranged on the walkway. The hoist trolleys may of course be automotive and independent of a winch.

[0056] In Figure 2 a pulley 14 is arranged between the hoist trolley 10 and the attachment point 5 of the net pen 1. By adjusting the rope 11 between the pulley 14 and the attachment point 5 of the net pen, the net pen may be expanded, and / or moved closer or further away from any of the legs.

[0057] In Figure 2 the net pen is shown provided with a pipe 15 running from the bottom of the net pen to the leg 3. The shown pipe 15 is a part of a system for removal of dead fish and sludge being collected at the bottom of the net pen.

[0058] In Figure 3 it is shown a rack and pinion connection 16 between the walkway 2 and the leg 3, wherein the rack is arranged at the corner between sides 3a and 3b of the leg, facing away from the net pen. The means for operating the rack and pinion is not shown. Further, the walkway 2 is shown as one part having a recessed corner, wherein the leg 3 is inserted in the recess. The walkway may of course also be provided in several parts being connected to each other and / or the leg.

[0059] The walkways are adjacent to the sides 3a and 3b of the leg, and the side 3c facing the net pen 1 is exposed. The hoist trolleys are attached to the rail 9 of the third side 3c and may run along the rail 9 through the walkway, and thus the net pen may be elevated above the walkway.

[0060] In Figure 4 and 5 the net pen 1 are shown in a position above the walkway 2. This may be advantageous when the net pen should be cleaned, replaced and / or transported. In Figure 4 the legs are elevated into and above the walkways, and thus the fish cage has no parts protruding into the water. The position shown in Figure 4 will be advantageous when the cage should be moved for instance towed to a new localization. By a fish cage according to the invention, in case of bad weather or if algae or other organisms such as salmon lice appear in the upper parts of the water, the net pen may be submerge quickly by lowering the hoist trolleys. Further, the fish farmers will have full access to the fish cage from the walkways by elevating the net pen, and possibly moving it closer to one side by adjusting the pullies. When the fish in the net pen should be removed, the hoist trolleys may be elevated until parts of the net pen is above the water and thus the fish will be crowded and more easily to remove.

Claims

Patent claims1. Fish cage comprising a net pen (1), walkways (2) and at least three legs (3), wherein the legs (3) are arranged to be mounted on the sea bed (4) and walkways (2) are arranged between the legs (3), and attached to the legs, leaving an exposed side (3c) or axial area of each leg facing towards the net pen (1), the net pen (1) is attached to the exposed side or area of each leg (3) at two or more different attachment points (5), and the legs (3) are arranged to keep the net pen expanded.

2. Fish cage according to claim 1 , wherein the net pen (1) is attached to the legs (3) in such a way that the net pen (1) may be moved in relation to the legs (3).

3. Fish cage according to claim 3, wherein at net pen is attached to the legs by a least one hoist trolley (10) on each leg.

4. Fish cage according to claim 2 or 3, wherein at least one hoist trolley (10) on each leg (3) are connected to a winch (12) arranged on the walkway (2).

5. Fish cage according to any one of claims 2-4, wherein at least one pulley (14) is arranged between the attachment point (5) of the net pen (1) and the leg (3).

6. Fish cage according to any of the preceding claims, wherein the walkways (2) are attached to the legs (3) by a rack and pinion system (16), or by a system of actuators and locking holes.

7. Fish cage according to any of the preceding claims, wherein the legs have an inner axial space.

8. Fish cage according to any of the preceding claims, wherein a roof (8) of net and / or impermeable material is fastened to and arranged above the net pen.

9. Fish cage according to any one of the preceding claims, wherein the legs and / or walkways are made of truss framework.

Images