A bouyancy apparatus for use in a shellfish growing system

Abstract

The apparatus, system and method of the present invention is for the cultivation of shellfish, such as oysters, in subtidal environments. The apparatus includes a buoyancy module for baskets in which the shellfish are cultivated. In use, the baskets are supported by the buoyancy module, either from underneath, with baskets uppermost in the water, or from above, with the buoyancy module uppermost. The buoyancy module is configured with a vent structure such that the user of the system is able to adjust its buoyancy as needed, for example to submerge the baskets beneath the water to avoid or reduce damage that may be caused by adverse weather conditions.

Description

[0001] A BOUYANCY APPARATUS FOR USE IN A SHELLFISH GROWING SYSTEM

[0002] STATEMENT OF CORRESPONDING APPLICATIONS

[0003] This application is based on New Zealand Patent Application No. 800965, filed 16 June 2023, and New Zealand Patent Application No. 808561 , filed 23 February 2024, the entire contents of which are incorporated herein by reference.

[0004] TECHNICAL FIELD

[0005] The present invention relates to an apparatus for use in a shellfish growing system for the cultivation and harvesting of shellfish, such as oysters. The present invention may have particular application to providing buoyancy to shellfish cultivation baskets used in subtidal (i.e. offshore) locations.

[0006] BACKGROUND ART

[0007] Shellfish can be cultivated in a number of ways. One technique is the use of "single seed" growing systems may be used wherein the shellfish spat is contained relatively freely within a holding container such as a basket, to grow to maturity and / or a harvestable size. It is generally considered that single seed systems tend to produce higher quality shellfish than techniques involving attachment of shellfish spats to a growing medium.

[0008] A common configuration for a single-seed growing system is known as the "adjustable longline system". This system, which may be used intertidally or sub-tidally, comprises a plurality of substantially cylindrical baskets that may be openable at one or both ends. Each basket includes clips or structures for attachment to one or more longlines, i.e. cables or ropes that are strung across the intended farming region.

[0009] In some systems, the baskets may include floats or buoyancy aids proximate the top of the basket, such that, in use, the basket is submerged while being maintained proximate the surface of the water by the buoyancy aid. Both subtidal and intertidal systems may include this feature. In the case of intertidal systems, the inclusion of a buoyancy aid allows for additional movement of the basket with the rise and fall of the tide, which may help to shape the growing oysters.

[0010] One such system used sub-tidally is described in PCT Publication No. WO2019 / 151879; in this system, the basket is mounted to a cable such that it is able to be rotated or flipped. This allows the shellfish farmer to periodically expose the shellfish inside the basket to air.

[0011] The system of WO2019 / 151879 is advantageous since it allows the shellfish farmer to utilise the benefits of the subtidal zone, such as relatively inexpensive farming locations, remote from shore, as well as cheaper growing infrastructure and access to the farming site independently of tides, while at the same time potentially gaining the growth characteristics seen in shellfish cultivated in an intertidal zone, which typically are a harder shell, better adductor strength (which can result in longer shelf life) and better overall conditioning. This may be due to the shellfish being alternately submerged and exposed to air, prompting behavioural responses (such as adductor muscle activity) as well as allowing the shells to dry out when elevated from the water, which may mitigate biofouling. Intertidal systems may also have fewer issues with biofouling and less risk of damage to growing infrastructure as a result of wave action.

[0012] The use of a buoyancy aid is important for such systems since these allow the baskets to be floated on or proximate the water surface. In many cases, the buoyancy aids are blocks of foam or the like.

[0013] However, in some instances it may be necessary to place the cultivation system beneath the water surface, particularly when the system is being used in unsheltered or open water and where there is potential for seasonal ice formation.

[0014] This may be desirable, for instance, in the event of adverse weather conditions. When wave action is particularly turbulent, such as may occur during periods of high winds or a storm event, this may affect the rate of growth of the shellfish being cultivated. Placing the system beneath the water surface or on the substrate may help minimise the effects of wave action and lower stress on the shellfish.

[0015] In another example of a situation where it may be desirable to fully submerge the cultivation system is in winter months. This may be preferable in order to avoid issues around ice formation on the water surface. This has the potential to damage the apparatus of the cultivation system as well as affecting or even fatally harming shellfish.

[0016] In these instances, instead of foam being used as a buoyancy aids, structures with a hollow interior are used instead. To access to the interior of these hollow buoyancy aids, an aperture, governed by caps or similar structures, is provided.

[0017] When it is necessary to reduce the overall buoyancy of the basket, and thus lower it within the water column, the caps are removed to allow water to enter the interior of the buoyancy aid. However, this is a time consuming process, particularly if some partial buoyancy is still desired (such as when the basket only needs to be slightly below the water surface rather than on the substrate) since the farmer or worker has to wait for an appropriate amount of water to enter the buoyancy aid before replacing the cap.

[0018] These arrangements are also problematic when it is desirable to raise the basket within the water column. In order to achieve this, the basket must be lifted out of the water to drain. When full of water, the buoyancy aid can be extremely heavy and care must be taken to ensure that the basket and attached buoyancy aid is safely lifted out of the water.

[0019] Furthermore, the caps themselves may fail or leak which could lead to water unintentionally entering the buoyancy aid and affecting buoyancy of the overall cultivation system.

[0020] Alternatively, the buoyancy modules themselves may be removed from the baskets. However, this has the drawback leaving the shellfish farmer of no option but allowing the baskets to fall to the substrate; there is no possibility of only partially submerging the basket. Furthermore, this then leaves the shellfish farmer having to transport and store the buoyancy modules once removed. As the modules tend to be bulky, the transportation and storage of these can create logistical problems.

[0021] It is an object of the present invention to address the foregoing problems or at the very least to provide the public with a useful choice.

[0022] All references, including any patents or patent applications that may be cited in this specification are hereby incorporated by reference. No admission is made that any such reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications may be referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.

[0023] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of "including, but not limited to".

[0024] DISCLOSURE OF THE INVENTION

[0025] According to one aspect of the invention, there is provided a buoyancy module for use with a basket for cultivation of shellfish, wherein the buoyancy module includes: a body with a hollow interior, wherein the body has a length dimension, wherein the length dimension has a first end portion, a centre portion, and a second end portion, and wherein the body has an upper side and a lower side; a vent structure provided to or proximate the lower side of the body, wherein the vent structure is located substantially on one of the first end portion, centre portion, or second end portion of the length dimension of the body; and wherein the vent structure is configured with an aperture that is communicative with the hollow interior of the body.

[0026] According to one aspect of the invention, there is provided a buoyancy module for use with a basket for cultivation of shellfish, wherein the buoyancy module includes: a body with a hollow interior, wherein the body has a length and width dimension, wherein the length dimension has a centre portion and the width dimension has a centre portion, and wherein the body has an upper side and a lower side; a vent structure provided to or proximate the lower side of the body, wherein the vent structure is located substantially along one of the centre portions of the length or width dimensions of the body; and wherein the vent structure is configured with an aperture that is communicative with the hollow interior of the body.

[0027] According to one aspect of the invention, there is provided a buoyancy module for use with a basket for cultivation of shellfish, wherein the buoyancy module includes: a body with a hollow interior, wherein the body has a length dimension, wherein the length dimension has a first end, a second end, and a centre portion, wherein the first end and second end are separated by the centre portion, and wherein the body has an upper side and a lower side; a vent structure provided to or proximate the lower side of the body, wherein the vent structure is located substantially at one or both of the first and second ends of the length dimension of the body; and wherein the vent structure is configured with an aperture that is communicative with the hollow interior of the body. According to one aspect of the invention, there is provided a system for cultivation of shellfish, the system including: a cable; and one or more baskets for cultivation of shellfish, and one or more buoyancy modules buoyancy module for use with a basket, wherein the buoyancy modules are as substantially as described above.

[0028] According to another aspect of the invention, there is provided a method of using a system for growing shellfish substantially as described above, the method including the steps of: a) seeding at least one basket with a plurality of shellfish; b) mounting the at least one basket to a cable; c) attaching the buoyancy module to the at least one basket; and d) placing the at least one basket in a marine or freshwater environment.

[0029] According to another aspect of the present invention, there is a method substantially as described above, the method including the additional step of: e) rotating the at least one basket about an axis of rotation defined by the cable to invert one or more baskets.

[0030] The apparatus, system and method of the present invention is for the cultivation of shellfish in subtidal environments. In particular, the invention should be understood to be a buoyancy module for the baskets used for the cultivation of shellfish. In use, the baskets are supported by the buoyancy module, either from underneath, with baskets uppermost in the water, or from above, with the buoyancy module uppermost. The buoyancy module is configured such that the user of the system is able to adjust its buoyancy as needed. Although reference is made to the cultivation of shellfish taking place in a marine environment, i.e. used in seawater to cultivate marine species of shellfish, it will be understood that the invention may be used in bodies of fresh water, such as lakes, to farm freshwater species of shellfish.

[0031] In exemplary embodiments of the invention, the shellfish are oysters and reference to this effect shall be made throughout the remainder of the present specification. However, this is not meant to be limiting and the invention may be used for cultivation of other shellfish and marine or freshwater species such as scallops, sea urchins, or crustaceans.

[0032] The baskets used for the cultivation of the oysters should be understood to be a substantially enclosed structure having a top, bottom, left and right sides, front and rear ends. The sides of the basket are mesh-like or otherwise provided with apertures to allow water to enter the basket.

[0033] In exemplary embodiments, the baskets have an elongate dimension such that they assume a substantially rectangular or cylindrical form, but in other embodiments the length and width of the baskets may be substantially the same.

[0034] The mesh is sized such that the oysters to be contained by the basket is not allowed to escape. In most embodiments, the oysters are free to move within the basket. This allows them to move to favourable positions for feeding and optimising growth. However, in some embodiments, the basket may be provided with growing surfaces, such as racks or the like, on which oyster spats may be "seeded" or otherwise attach themselves to.

[0035] The baskets may be provided with a range of mesh sizes, depending on the relative mature of the oysters contained therein. For example, baskets in which spats are seeded may have a relatively fine mesh. Once the spats have grown, they may be graded and transferred to another basket having a coarser mesh. The front and rear ends of the basket should be understood to be configured to allow access to the interior of the basket. This will be achieved in a number of ways readily apparent to persons skilled in the art; for example, the front and rear ends may be configured as flaps, with one edge hinged ly mounted to the basket such that it can be opened and closed. A locking mechanism may be present ensure that the basket is not accidentally opened.

[0036] Note that in the following discussion, reference to the top of the basket should be understood to mean the uppermost side of the basket which engages and contacts the buoyancy module in use. In a first condition, when in the water, the basket hangs beneath the buoyancy module immersing the oysters contained therein. In a second condition, when the basket, and therefore the buoyancy module, has been rotated though an arc of around 180° from the first condition, the basket sits substantially on top of the buoyancy module with the bottom, or lowermost side exposed. In this second condition, depending on the buoyancy provided by the buoyancy module, the oysters contained within the module may be substantially out of the water.

[0037] In some examples, the baskets are configured to be used with cables or wire ropes which connects or otherwise links a plurality of baskets to each other in series. In some of these examples, the cable may be connected or otherwise mounted to or proximate the bottom of the baskets such that they (the baskets) may be rotated or flipped in order to invert them. The cable may be connected directly to the ends of the baskets or in some embodiments, connect or pass through support brackets provided to the bottom of the baskets.

[0038] In other examples, the cable may alternatively be connected or otherwise mounted to the buoyancy modules of the system. This connects or otherwise links a plurality of buoyancy modules to each other in series. In some of these examples, the manner of connection is such that they (the buoyancy modules) may be rotated or flipped in order to invert them. In some embodiments of the invention, the cables may be mounted to the baskets or buoyancy modules such that the axis of rotation is along the elongate dimension of the basket or buoyancy module. In other embodiments, the cables may be mounted to the baskets or buoyancy module such that the axis of rotation is substantially perpendicular to the elongate dimension of the basket or buoyancy module.

[0039] The basket is to be used with a buoyancy module substantially as herein described. In some embodiments, the buoyancy module may be configured as part of the basket, i.e. integral to the basket, but in exemplary embodiments is separate to the basket. Reference to the latter embodiment shall now be made throughout the remainder of the specification but persons skilled in the art will appreciate the modifications that may be required for an integrated basket and buoyancy module.

[0040] The buoyancy module has a body that has a void in its interior, i.e. it is substantially hollow. It will be understood that the body is at least partially buoyant due to the presence of air within the hollow interior of the buoyancy module.

[0041] In exemplary embodiments of the invention, the buoyancy module may be a blow, injection or rotationally moulded structure of a plastics material, such as high density polyethylene (HDPE) or similarly robust and hardwearing plastics material such as polyethylene (PE). Note that these are nonlimiting examples, and other materials recognised as being suitable for the purpose may be used, including, and without limitation, the likes of fibreglass or even sheet metal.

[0042] The body of the buoyancy module has a length dimension, a width dimension and a depth dimension, which collectively defines the overall volume of the buoyancy module. The relative dimensions may vary in respect of each other but it will be understood that whatever dimensions are used, they should be sufficient such that there is sufficient buoyancy achieved by the interior of the body to remain afloat even when loaded with a basket and shellfish. In exemplary embodiments, the length dimension of the body is substantially longer than its width dimension such that the buoyancy module assumes a substantially rectangular or cylindrical form. In alternative embodiments the length and width of the buoyancy module may be substantially the same. It will be appreciated that at least a portion of the body of the buoyancy module should be substantially complementary to the shape of the basket with which it is to be used.

[0043] In some embodiments, the length dimension of the body may have three substantially equal portions, two end portions and a centre portion, at the middle of which is a centre axis, a line along which the buoyancy module may be split into equal halves. It will also be understood that the width dimension also may have three substantially equal portions, two end portions and a centre portion, at the middle of which is a centre axis, a line along which the buoyancy module may be split into equal halves.

[0044] In other embodiments, the length dimension of the body may have three portions: two end portions (or a first end portion and a second end portion) and a centre portion. The centre portion may form a substantial proportion of the overall length dimension. In one non-limiting example, the centre portion may form 90% of the overall length dimension, and each end portion forms 5% of the overall length dimension. In another non-limiting example, the centre portion may form 70% of the overall length dimension, and each end portion forms 15% of the overall length dimension. At the middle of the centre portion is a centre axis, a line along which the buoyancy module may be split into equal halves.

[0045] The body of the buoyancy module should be understood to have an upper side and a lower side.

[0046] The lower side should be understood to mean the side of the buoyancy module that in use engages or otherwise contacts and bears against the top side of the basket with which it is to be used. In the first condition, the lower side of the buoyancy module faces the sea or lake bed, with the basket hanging beneath the buoyancy module. Conversely, the upper side of the buoyancy module faces away from the sea bed. Depending on the overall buoyancy, the upper side of the buoyancy module may be out of the water.

[0047] The engagement between the basket and buoyancy module may be achieved in a number of ways. For example, straps or fasteners may be used to secure the buoyancy module to the basket. In other embodiments, large fasteners such as pins or bolts may pass through the buoyancy module into the basket, which is configured with threaded apertures to receive the fasteners or receives complementary fasteners to secure the buoyancy module.

[0048] Alternatively, the lower side of the buoyancy module may be provided with structures that interlock or receive with complementary structures on the basket. The interlocking functionality may be through the use of a snap-fit type connection, pegs, or complemented with the use of basic fasteners, such as pins or bolts.

[0049] Persons skilled in the art will readily appreciate other ways in which the lower side of the buoyancy module and the basket may be configured to allow them to engage with each other. Given the nature of the environment in which the invention is to be used, it will be appreciated that whatever the manner of engagement between the basket and the buoyancy module, it should be durable and robust.

[0050] It will be appreciated that it could be useful to control the buoyancy of the basket with which the buoyancy module is to be used. For example, if a major weather event such as a storm is likely to occur, the shellfish farmer may opt to admit water into the interior of the buoyancy module such that it, and the basket, sinks below the surface of the water or even to the substrate. This reduces the risk of damage to the equipment. The same approach may be used if there is a risk of ice formation.

[0051] The lower side of the buoyancy module is configured with at least one vent structure. This should be understood to be a protrusion extending away, in a manner similar to a funnel, from the lower side of the buoyancy module. In some examples, the at least one vent structure may be provided to a surface proximate the lower side, for example at or just above the juncture between the lower side and a surface linking the lower side and the upper side.

[0052] The vent structure includes at least one aperture or opening which is communicative with the interior of the body of the buoyancy module. Preferably, the apertures are provided at or proximate the ends of the protrusions that form the vent structure.

[0053] In some embodiments, the vent structure should be understood to be placed substantially in the centre portion of one of the length or width dimension of the buoyancy module. It should be appreciated that this locates the vent structure generally centrally on the lower side of the buoyancy module.

[0054] Preferably, the vent structure is placed to one side of the centre portion, off the line of the centre axis. Even more preferably, the vent structure is placed to the extreme side of the centre portion, i.e. the edge of the centre portion. This will be understood to correspond to one end of the width dimension of the body of the buoyancy module

[0055] In other embodiments, the vent structure should be understood to be placed substantially at one of the end portions of the length or width dimension of the body of the buoyancy module. It should be appreciated that this locates the vent structure generally at one end of the lower side of the buoyancy module.

[0056] Preferably, the vent structure is dimensioned to substantially span the width dimension of the body of the buoyancy module. However, in some embodiments the vent structure may be dimensioned smaller than the width dimension.

[0057] Preferably, the buoyancy module is provided with a first vent structure as described herein, and a second vent structure, also as described herein. In one example, the vent structures are provided on respective sides of the centre portion. In another example, the vent structures are provided to both ends of the length dimension of the body of the buoyancy module.

[0058] Having two vent structures may be helpful in providing an avenue, via the first vent structure, for air to escape the interior as water ingresses via the second vent structure (or vice versa as the case may be). This can help with efficiency in filling the buoyancy module, as well as better assisting in draining water as required.

[0059] In some embodiments, a portion of the buoyancy module is configured with a recess or depression that is complementary to the shape and dimensions of the vent structure. This is advantageous for storage and transportation of the buoyancy modules, since this allows them to be stacked.

[0060] When in use, this central position for the vent structure optimises the placement of the apertures depending on the usage of the invention.

[0061] For example, when the buoyancy module is in the first condition, such that the basket is suspended in the water, the aperture is located below the water level.

[0062] It will be appreciated that when the cultivation system is in the first condition, i.e. the vent structure of the buoyancy modules making up the cultivation system depends downwards towards the seabed, the air within the hollow interior prevents significant undesired ingress of water into the interior of the buoyancy module or, already if present, undesired egress of water.

[0063] In embodiments so configured, the placement of the vent structure at the centre portion of the lower side of the buoyancy module means that even in relatively strong wave action, there is substantial contact with the surface of the water. If the vent structure was located towards the ends of the elongate dimension of the buoyancy module, it is possible that the vent structure, and the aperture of same, will not contact the water. In this case, if water is present in the interior of the body, it is able to drain away, possibly making the buoyancy module more buoyant and increasing its height in the water.

[0064] In embodiments configured with vent structures at one end of the lower side of the buoyancy module, the relative height of said structure may be increased so as to keep its aperture of same below the level of the water for as long as possible during relatively strong wave action.

[0065] The vent structure is also useful when the cultivation system is in the second condition as it also makes it relatively easy for the user to artificially decrease its buoyancy if needed. For instance, in particularly adverse weather conditions, to avoid damage to the overall cultivation system, the user may deliberately apply a force to the buoyancy module, by pushing it under the surface of the water to such an extent that the ends of the vent structure are under water, thereby allowing water to enter. This decreases the buoyancy, settling the cultivation system deeper in the water column and reducing its exposure. Alternatively, the buoyancy module may be rotated through an arc of around 90° from the first condition; this places the vent structures substantially horizontal, thereby allowing water to enter. Similarly, this decreases the buoyancy, and once this has been sufficiently achieved, the buoyancy module may be allowed to return to the first condition.

[0066] In some embodiments, the vent structure may include a plurality of apertures; for instance, the aperture may be configured as a mesh to filter water which may enter the interior of the body of the buoyancy module. This may help reduce the possibility that waterborne debris, such as seaweed and the like, may enter the interior of the body.

[0067] In exemplary embodiments, the vent structure is tapered, such that it narrows as it extends away from the lower side of the buoyancy module, with the aperture provided to the end of the funnel. In other embodiments, the vent structure lacks tapering and has a generally consistent cross-sectional area along its length. In use, a buoyancy module as described herein is secured to the top side of each basket of an oyster cultivation system. Following the introduction of oyster spats to the baskets, they are lined up and a cable connected or otherwise mounted to the baskets (or buoyancy modules).

[0068] In one example, if not already in the seawater, the baskets are then lowered into the sea, orientated such that the lower sides of the buoyancy modules face downwards, i.e. the vent structures of the respective buoyancy modules are below the water surface. This is the first condition, which effectively suspends the baskets from the undersides of the buoyancy modules.

[0069] In another example, the baskets are lowered into the sea such that the vent structures, or at least the apertures provided to the vent structures, of the buoyancy modules are above the water surface; this places the baskets above the water surface, in the second condition. With appropriate equipment, the buoyancy modules of the cultivation system may be flipped or otherwise rotated through an arc of 180° to move between the first and second conditions as required.

[0070] At either end, the cable is secured, either by an anchor or, depending on the area in which the invention is to be used, to poles or moorings. This allows the cultivation system to be used in seawater of any depth.

[0071] Placed such that the buoyancy module is uppermost, the basket itself is just below the water surface. This fully immerses the oysters in the seawater, encouraging faster growth. The presence of the buoyancy module also protects the growing oysters from seabirds that may otherwise penetrate the mesh of the baskets and eat the oysters.

[0072] Although the vent structures of the buoyancy module have apertures at their ends, the air trapped inside the body prevents the water from entering the interior of the buoyancy. At the same time, the dimensions of the buoyancy module are such that it displaces less water than its weight, even with the basket attached, that it too remains buoyant. Thus, the respective components remain buoyant, floating on the surface with the basket containing the oysters suspended in the water beneath (or above the water, when in the second condition).

[0073] If necessary, for example to reduce the exposure of the cultivation system to inclement weather by reducing its height in the water column, the operator may place the buoyancy module into the second condition, with the vent structures uppermost and then push or otherwise urge the buoyancy module downwards such that the apertures of the vent structures are beneath the water. Alternatively, the baskets could be slowly rotated from the first condition, through an arc of 90° such that the vent structures are orientated substantially horizontally. Either way, this allows water to enter the buoyancy module, thereby making it less buoyant.

[0074] Conversely, through the use of appropriate handling equipment, for example a winch-operated hook, a vessel can come alongside the cable and by rotating it, such that the vent structures face downwards and lifting it out of the water, this facilitates the raising of an immersed cultivation system. If raised above the water surface by a sufficient height, any water is able to drain from the interior of the buoyancy module, making it more buoyant. If required, the baskets of the cultivation system may be rotated. The buoyancy module remains substantially on the water surface but now in the second condition, with the basket exposed. This allows the basket to opened, inspected and so on. There is no need for the entire basket to be lifted and located onto the deck of the vessel. This saving in handling means considerable space and labour reductions. It is not necessary to transport the baskets to shore for collection and grading. Once graded, the oysters can put into an appropriate basket and returned to the sea.

[0075] The vessel will move along the line, raising and emptying the baskets as required. In the interim, the empty baskets, now floating on their buoyancy modules, are exposed to the air. This helps dry them out and minimise or control any fouling. Alternatively, the raising and rotation of the baskets may be for the purpose of exposing the oysters and basket to the air for a period of time. By repeating this on a regular basis, this can simulate an intertidal growing environment even though the baskets are being used in a subtidal environment. Benefits of this could include improved shell hardness and better conditioning.

[0076] The present invention provides a buoyancy module for use with a basket of a system for the cultivation of shellfish in a sub-tidal environment that offers a number of advantages, including:

[0077] • ability to control the extent of buoyancy of the cultivation system;

[0078] • ability to temporarily sink the cultivation system to the substrate to avoid climatic events such as hurricanes or ice and minimise risk of equipment damage; or

[0079] • may be easier to maintain the cultivation systems, with subsequent reduced costs in time and labour.

[0080] At the very least, the present invention offers the public a useful choice.

[0081] Further aspects of the invention, which should be considered in all its novel aspects, will become apparent to those skilled in the art upon reading of the following description which provides at least one example of a practical application of the invention.

[0082] BRIEF DESCRIPTION OF THE DRAWINGS

[0083] One or more embodiments of the invention will be described below by way of example only, and without intending to be limiting, with reference to the following drawings, in which:

[0084] Figure 1 is a perspective view of a buoyancy module of one exemplary embodiment of the present invention;

[0085] Figure 2 is a second perspective view of the buoyancy module of Figure 1 ; Figure 3 is a perspective view of the buoyancy module of Figure 1 with an oyster cultivation basket; and

[0086] Figure 4 is a perspective view of a buoyancy module of an alternative exemplary embodiment of the present invention.

[0087] BEST MODES FOR CARRYING OUT THE INVENTION

[0088] One embodiment of the buoyancy module, generally indicated by arrow 100, of the present invention is illustrated in Figures 1 and 2.

[0089] The buoyancy module 100 is blow moulded from plastics material, such as high-density polyethylene (HDPE) or polyethylene (PE), which is relative robust and hard wearing, even in a marine environment. However, this is not meant to be limiting and other types of material, plastics or otherwise, and manufacturing techniques, such as injection or rotational moulding, may be used.

[0090] The buoyancy module 100 of Figures 1 and 2 is substantially hollow and configured more or less as a rectangle in plan view, and as indicated in Figure 1 , has a length dimension (L-L), a width dimension (W-W), and a depth dimension (D-D). These collectively define the volume of the buoyancy module. Each of the length and width dimension has a centre axis line as indicated.

[0091] The length dimension (L-L) has three distinct portions, each being the same size; two end portions, identified by E1 and E2, and a centre portion, identified by C and demarcated by lines W1 -W1 (which define end portion E1 ), and W2-W2 (which define end portion E2) respectively. As can be seen, the centre axis line of the width dimension is central to the centre portion.

[0092] It should be appreciated that the buoyancy module 100 has an upper side US and a lower side LS. In use, as shown in Figure 3, a basket B, when being used as part of a shellfish cultivation system (not shown), is secured or otherwise engaged with the lower side of the buoyancy module 100. Returning to Figures 1 and 2, the lower side LS of the buoyancy module 100 is configured with a pair of vent structures 102. In the illustrated example, the vent structures 102 are placed slightly off the centre axis line W-W of the width dimension of the buoyancy module but still substantially within the centre portion C. It is also placed favouring one edge of the length dimension L-L of the buoyancy module. This is advantageous since the surface of the buoyancy module defining its depth dimension D-D may be configured with a recess 104 having complementary dimensions to those of the vent structures. This allows multiple buoyancy modules to nest together and be stacked atop of each other for storage and / or transportation purposes.

[0093] Having two vent structures 102 on opposing edges of the lower side LS is also useful in that this may provide greater efficiencies when filling / emptying the buoyancy module 100. Water may preferentially ingress one of the vent structures while the air displaced from the interior egresses the other vent structure. It will also be noted that the vent structures could be provided to the upright sides, linking the lower side and the upper side US of the buoyancy module, close to the juncture between the upright sides and the lower side.

[0094] As can be seen in Figures 1 and 2 of the buoyancy module 100, the depth dimension D-D varies along the length dimension L-L. In particular, the depth dimension is greater in the portion of the buoyancy module to which the vent structure is provided. However, the remaining portion has a depth dimension that is at least substantially equal, if not greater, than the height of the vent structure. This is so that when stacked, as discussed above, no part of the vent structure extends beyond the plane of the upper side US of the buoyancy module.

[0095] As already described, the lower side LS of the buoyancy module 100 is configured with a vent structure at the end of which is provided at least one aperture 106. This aperture is communicative with the interior of the buoyancy module. When the buoyancy module 100 is attached to the basket (not shown) with which it is to be used and has been rotated such that the basket is suspended in the water column, i.e. with the upper side of the buoyancy module facing upwards, the amount of water displaced is insufficient for it to come over the end of the vent structure and enter its interior. Thus, the air contained within the interior of the body of the buoyancy module provides buoyancy for the basket in use.

[0096] The placement of the vent structures 102, on opposing edges of the lower side LS of the buoyancy module 100, is helpful in use as it may assist in location and placement of the baskets with which it is to be used, as depicted in Figure 3.

[0097] In some embodiments not shown here, the lower side (LS) of the buoyancy module 100 may be configured in such a manner as to define a cradle or similar structure. This may be useful in helping orientation and placement of the buoyancy module relative to the basket (not shown). For example, two or more flanges or similar structures may be provided along the edges of the lower side of the buoyancy module to define a cradle or recess into which the basket may be located.

[0098] In use, when the buoyancy module is in the orientation shown in Figure 2, the basket (not shown) is effectively suspended under the buoyancy module 100, which is on the water surface. The lower side LS of the buoyancy module faces downwards, towards the sea or lake bed. This is the first condition of the buoyancy module, which immerses the basket in the water. To expose the basket, it just needs to be quickly flipped substantially through an arc of substantially 180° such that it rotates about the cable (not shown) connected to the basket (or the buoyancy module in some examples not shown here). This places the buoyancy module in the second condition, which is the orientation shown in Figures 1 and 3.

[0099] While the buoyancy module 100 remains more or less on the surface, although now inverted with the lower side LS uppermost, the basket (B in Figure 3) is now just above the surface of the water. It remains buoyant, through any air that is trapped within the interior of the body. The end of the vent structure is above the surface of the water.

[0100] The basket (B in Figure 3) may then be emptied and left on the surface to dry out or its contents inspected or simply left on the water surface to replicate the regular exposure that oysters grown i ntertidal ly may experience. This allows the shellfish farmer to replicate an intertidal environment using a subtidal growing system, which can result in superior oysters.

[0101] However, if the buoyancy module 100 is forced downwards upon application of a force, such that the vent structure 102 and the apertures 106 provided to the ends of same is beneath the water surface, this allows water to enter the interior of the buoyancy module. Alternatively, the buoyancy module is flipped slowly and held at a substantially 90° angle, this may allow water to enter the interior of the buoyancy module if desired. In some situations, this may be preferable to add some weight to the system for sake of stability while still allowing the basket (B in Figure 3) to be substantially exposed. Once a sufficient amount of water has entered, the basket may be released to complete its 180° rotation.

[0102] In some instances, it may be desirable to submerge the entire basket and buoyancy module 100, for example in winter months to prevent the system from becoming encased in ice or to reduce adverse wave action, such as typically occurs in a storm event and high swell.

[0103] In such a scenario, the baskets may be flipped, as described above such that they are above the surface. The baskets, with the attached buoyancy module 100, are then pushed below the water surface. It will be appreciated that this places the vent structure under water, allowing their interior to be filled with water.

[0104] Alternatively, rather than flipping the buoyancy module through a full arc of movement of substantially 180°, it may be rotated from the first condition through an arc of substantially 90° or sufficient such that water is able to enter the vent structures. This reduces the buoyancy of the buoyancy module 100, lowering the cultivation system in the water column. If the flipping of the basket is done sufficiently slowly enough, air is allowed to escape from the interior of the body of the buoyancy module such that it does not contribute much, if any, buoyancy. By controlling the amount of water entering the buoyancy module, the user can achieve the desired buoyancy for the cultivation system. In some instances, this may be used to create a negative buoyancy such that the entire system sinks to the substrate if necessary.

[0105] Once the system is ready to be used again, the basket and buoyancy module 100 is simply raised using a winch or the like and flipped about the cable to return it to the configuration shown in Figure 2; if raised to a sufficient height such that the vent structures are clear of the water surface the water within the body is allowed to drain away and the cultivation system regains its buoyancy. The placement of the apertures 106 at the tip of the vent structures 102 helps facilitate full drainage of the buoyancy module if desired.

[0106] An alternative embodiment of the buoyancy module 200 is shown in Figure 4. In contrast to the previous embodiment described, the vent structure 202 is provided to the end of the lower side LS of the buoyancy module. The vent structure substantially spans the width dimension of the buoyancy module, with the aperture 206 in the form of a slot. In this embodiment, the lower side includes structures 204 that interlock with complementary structures provided to the contact side of the basket (not shown) that is to be secured to the buoyancy module.

[0107] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of "including, but not limited to".

[0108] The entire disclosures of all applications, patents and publications cited above and below, if any, are herein incorporated by reference. Reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in the field of endeavour in any country in the world.

[0109] The invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features.

[0110] Where in the foregoing description reference has been made to integers or components having known equivalents thereof, those integers are herein incorporated as if individually set forth.

[0111] It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be included within the present invention.

Claims

THE CLAIMS DEFINING THE INVENTION ARE:

1. A buoyancy module for use with a basket for cultivation of shellfish, wherein the buoyancy module includes: a body with a hollow interior, wherein the body has a length dimension, wherein the length dimension has a first end portion, a centre portion, and a second end portion, and wherein the body has an upper side and a lower side; and a vent structure provided to or proximate the lower side of the body, wherein the vent structure is located substantially on one of the first end portion, centre portion, or second end portion of the length dimension of the body; and wherein the vent structure is configured with an aperture that is communicative with the hollow interior of the body.

2. The buoyancy module as claimed in claim 1 , wherein the body also has a width dimension, wherein the width dimension has a centre portion, and wherein the vent structure is located substantially along the centre portion of the width dimension of the body.

3. The buoyancy module as claimed in claim 1, wherein the first end portion and the second end portion of the length dimension are separated by the centre portion of the length dimension, and each of the first end portion and second end portion has a first end corresponding with the end of the buoyancy module and a second end adjacent the centre potion, and wherein the vent structure is located substantially at one or both of the first and second ends.

4. The buoyancy module as claimed in any one of claims 1 to 3, wherein the buoyancy module has a length dimension, a width dimension and a depth dimension, which collectively defines the overall volume of the buoyancy module.

5. The buoyancy module as claimed in claim 4, wherein the length dimension of the body is substantially longer than its width dimension such that the buoyancy module assumes a substantially rectangular or cylindrical form.

6. The buoyancy module as claimed in claim 4, wherein the length dimension and the width dimension of the buoyancy module is substantially the same.

7. The buoyancy module as claimed in claim 4, wherein the first end portion, the centre portion and the second end portion are substantially equal portions, wherein the centre portion has a centre axis, a line along the length dimension in which the buoyancy module is split into substantially equal halves.

8. The buoyancy module as claimed in claim 7, wherein the centre portion forms a substantial proportion of the overall length dimension.

9. The buoyancy module as claimed in claim 8, wherein the centre portion may forms between 70% to 90% of the overall length dimension, and each end portion forms 5% to 15% of the overall length dimension.

10. The buoyancy module as claimed in claim 4, wherein the width dimension also may have three substantially equal portions, two end portions and a centre portion, at the middle of which is a centre axis, a line along which the buoyancy module is split into substantially equal halves, wherein the centre axis of the width dimension is substantially perpendicular to the centre axis of the length dimension.11 . The buoyancy module as claimed in any one of claims 1 to 10, wherein the lower side of the body is configured to engage or otherwise contact and bear against the basket.

12. The buoyancy module as claimed in claim 11 , wherein the lower side of the body is configured with a) straps or fasteners to secure the buoyancy module to the basket; and / or b) structures that interlock or receive with complementary structures on the basket.

13. The buoyancy module as claimed in any one of claims 1 to 12, wherein at least a portion of the body of the buoyancy module is substantially complementary to the shape of the basket with which it is to be used.

14. The buoyancy module as claimed in any one of claims 1 to 13, wherein the vent structure is a protrusion extending away from the lower side of the body of the buoyancy module.

15. The buoyancy module as claimed in any one of claims 1 to 14, wherein the vent structure is a protrusion provided to a surface proximate the lower side of the body.

16. The buoyancy module as claimed in claim 15, wherein the protrusion is provided at or just above the juncture between the lower side of the body of the buoyancy module and a surface linking the lower side and the upper side of the body of the buoyancy module.

17. The buoyancy module as claimed in any one of claims 14 to 16, wherein the protrusion is tapered, such that it narrows as it extends away from the lower side of the body of the buoyancy module.

18. The buoyancy module as claimed in any one of claims 14 to 16, wherein the protrusion is untapered and has a generally consistent cross-sectional area along its length.

19. The buoyancy module as claimed in any one of claims 14 to 18, wherein the protrusion is dimensioned to substantially span the width dimension of the body of the buoyancy module.

20. The buoyancy module as claimed in any one of claims 14 to 18, wherein the protrusion is placed to one side of the centre portion of the width dimension, off the line of the centre axis.

21. The buoyancy module as claimed in claim 20, wherein the protrusion is placed to an extreme side of the centre portion of the width dimension, i.e. an edge of the centre portion.

22. The buoyancy module as claimed in any one of claims 14 to 21, wherein the aperture of the vent structure is provided at or proximate the end of the protrusion.

23. The buoyancy module as claimed in any one of claims 1 to 22, wherein the aperture of the vent structure is provided with a mesh.

24. The buoyancy module as claimed in any one of claims 1 to 23, wherein a portion of the buoyancy module is configured with a recess or depression that is complementary to the shape and dimensions of the vent structure.

25. The buoyancy module as claimed in any one of claims 1 to 24, wherein the vent structure is the first of two vent structures, wherein the second vent structure is positioned on an opposing side of the buoyancy module to the first vent structure.

26. The buoyancy module as claimed in any one of claims 1 to 25, wherein the buoyancy module is configured as part of the basket.

27. The buoyancy module as claimed in any one of claims 1 to 25, wherein the buoyancy module is a blow, injection or rotationally moulded structure of a plastics material.

28. The buoyancy module as claimed in claim 27, wherein the plastics material is high density polyethylene (H DPE) or polyethylene (PE).

29. A system for cultivation of shellfish, the system including: a cable; and one or more baskets for cultivation of shellfish, andone or more buoyancy modules for use with the one or more baskets, wherein the buoyancy modules is as claimed in claim 1.

30. A method of using a system for growing shellfish as claimed in claim 29, wherein the method includes the steps of: a) seeding at least one basket with a plurality of shellfish; b) mounting the at least one basket to a cable; c) attaching the buoyancy module to the at least one basket; and d) placing the at least one basket in a marine or freshwater environment.

31. A method of using a system for growing shellfish as claimed in claim 29, wherein the method includes the steps of: a) seeding at least one basket with a plurality of shellfish; b) attaching the buoyancy module to the at least one basket; c) mounting the buoyancy module to a cable; and d) placing the at least one basket in a marine or freshwater environment.

32. The method as claimed in claim 30 or claim 31, wherein the method includes the additional step of: e) rotating the at least one basket about an axis of rotation defined by the cable to invert one or more baskets.

33. The method as claimed in any one of claims 30 to 32, wherein the cables are mounted to the baskets or buoyancy modules such that the axis of rotation is substantially along an elongate dimension of the basket or buoyancy module.

34. The method as claimed in any one of claims 30 to 32, wherein the cables are mounted to the baskets or buoyancy modules such that the axis of rotation is substantially perpendicular to an elongate dimension of the basket or buoyancy module.

35. The method as claimed in any one of claims 30 to 34, wherein the shellfish are oysters.

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