FIELD OF THE INVENTION

The present invention relates to an aquaculture farming arrangement and in particular to an apparatus for the containment and cultivation of molluscs, in particular abalone and other suitable underwater species of the genus Haliotis.

BACKGROUND OF THE INVENTION

Abalone are large edible marine molluscs of the genus Haliotis having an ear- shaped shell with pearly interior. Abalone has become a high value product, grown in Australia specifically for export markets in Asia, but can be grown in the seas about many other countries. Two species are commonly harvested those being: Haliotis rubra (blacklip abalone) and Haliotis laevigata (greenlip abalone). Abalone are mobile bottom dwellers and graze on drift seaweeds and algae on rock surfaces. Abalone prefer rocky bottoms which they can crawl over or reside under in the darker areas.

In response to the increased global demand for abalone, numerous businesses have made attempts to farm abalone since natural sources are being depleted. Land based aquaculture methods are the most popular methods used to farm abalone, however there are a limited number of ocean-based (or sea-based) aquaculture farming methods that have been attempted.

Land based methods suffer from a number of disadvantages, most notably the high capital and operational costs involved in pumping sea water onto land. An additional disadvantage to the high capital costs is the risk associated with mechanical failure. Land based methods also require a great deal of space in order to set up an efficient farming operation and suitable locations are restricted to those with suitable site facilities. It is preferred that the sites have access to 3-phase power, gently sloping land and suitable water temperature,

etc. A further problem is that land-based farming methods rely on feeding manufactured pellets to the abalone. The current arrangements therefore require input of labour to feed and clean the abalone containers.

Ocean-based aquaculture arrangements can also be costly where the farming methods require divers to maintain and introduce feed into the farming containers by hand. From a farming perspective it is desirable to have as many abalone in a container as possible. If feed is not introduced then the population which a container can support is significantly decreased.

Prior arrangements also struggle to achieve consistent growth rates and problems with disease which have caused significant mortalities resulting in ongoing commercial losses.

As demand for abalone has increased, the cost-effectiveness of existing abalone farming apparatus and methods has deteriorated. Accordingly there is a need for an abalone farming arrangement which produces high yields of abalone at reduced costs. It is an object of the present invention to reduce or eliminate some or all of the disadvantages of abalone farming arrangements discussed above, or to at least provide a useful alternative.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided an abalone cultivating container for use in a flowing body of water, the container including; a cultivation region where abalone reside; and a water flow control arrangement to control the flow of water such that the flow is slower over the cultivation region than flow higher above the cultivation region.

Preferably the container further includes; at least one side wall; wherein the water flow control arrangement includes apertures in at least portions of the at least one side wall so as to control flow of water through said container.

More preferably, at least a portion of at least one of the at least one side walls is a mesh.

Preferably, the apertures in at least one of the at least one side walls of the cultivating container decrease in size towards the cultivation region thereby providing the water flow control arrangement.

Preferably, the container further includes; at least one buoyant support arrangement; wherein at least one of side walls is supported and depends from the buoyant support arrangement in the body of water.

Preferably the container is formed from mesh.

Preferably, the container further includes at least one structure for encouraging algae growth within the container.

More preferably the container further includes at least one support for at least one of the at least one algae growth structures that keeps the structure above the cultivation region.

Preferably at least one of the at least one structures that encourages algae growth is a net.

Preferably the at least one support is a rope.

Preferably, the at least one structure for encouraging the growth of algae is positioned so that algae which populates the structure rubs off when the structure rubs against itself or another structure.

More preferably, the at least one structure for encouraging algae growth within the container is located such that approximately half of the structure is on one side of the at least one supports and the other half of the structure is on the other side of at the at least one supports so that the halves of the structure are in proximity to one another so as to rub against itself.

Preferably, the cultivation region of the container is attached to at least one of the at least one side walls.

Preferably, the container further includes moveable and removable abalone habitats located at the cultivation region.

More preferably, the abalone habitats are moulded plastic.

Preferably, the surfaces of the abalone habitats are shaped so as to maximise surface area by providing surface undulations.

More preferably, the abalone habitats are elongated structures having a plurality of troughs and peaks.

Preferably, the abalone habitats are disposed within mesh pockets secured to the cultivation region by clips.

More preferably, the clips are snap-clips.

Perferably, the buoyant support arrangement includes a plurality of buoys.

Alternatively, the buoyant support arrangement is an elongate length of buoyant pipe.

Preferably, the buoyant support arrangement is partially filled with water.

More preferably, the buoyancy of the buoyant structure arrangement is adjustable by adding or discharging water ballast from the buoyant support.

Preferably, the at least one side wall of the container is joined to the buoyant support arrangement by ropes.

More preferably, the ropes which join the buoyant support arrangement to the container are slack, thereby allowing floating debris to flow through the container at the water surface level of the flowing body of water.

Preferably, the container is cylindrical in shape having at least one side wall.

More preferably, the container is annular in shape having at least two side walls.

Preferably there is a means for holding the container stationary with respect to a bottom surface of the body of water.

More preferably, the means for holding the container stationary with respect to the bottom surface of the body of water is an anchor.

According to a further aspect of the invention there is provided a method for cultivating abalone in a cultivating container according to any preceding claim disposed within a body of water, the method including the steps; placing the cultivating container in a body of water having algae; introducing immature abalone into the container at the cultivation region, if and only if a growth of algae exist on and in the container on or above the cultivation region.

Preferably the method further includes the steps: selecting abalone; and removing selected abalone from the cultivating container.

Preferably the method further includes placing within the cultivating container at least one structure for encouraging algae growth within the cultivating container.

More preferably the method further includes placing at least one support for at least one of the algae growth structures that keeps the structure above the cultivation region.

Preferably,, the method further includes positioning the structures for encouraging growth of algae so that algae which populate the structures rubs off when the structure rubs against itself or another structure.

More preferably the method further includes positioning the structure for encouraging algae growth such that approximately half of the structure is on one side of the at least one supports and the other half of the structure is on the other side of the at least one supports so that the halves of the structures are in proximity to one another so as to rub against itself.

Preferably, the method further includes placing of moveable abalone habitats within the container at the cultivation region.

According to another aspect of the invention there is provided a mesh for use in an abalone cultivating container disposed within in a flowing body of water having a cultivation region, the mesh being adapted to control the flow of water within the container such that the flow of water is slower over the cultivation region than flow higher above the cultivation region.

Preferably, the apertures in the mesh decrease in size towards the cultivation region.

Throughout this specification and the claims that follow unless the context requires otherwise, the words 'comprise' and 'include' and variations such as 'comprising' and 'including' will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that such prior art forms part of the common general knowledge.

Specific embodiments of the invention will now be described in some further detail with reference to and as illustrated in the accompanying figures. These embodiments are illustrative, and not meant to be restrictive of the scope of the invention. Suggestions and descriptions of other embodiments may be included within the scope of the invention but they may not be illustrated in the accompanying figures or alternatively features of the invention may be shown in the figures but not described in the specification.

BRIEF DESCRIPTION OF THE DRAWINGS An illustrative embodiment of the present invention will be discussed with reference to the accompanying drawings and examples wherein:

FIGURE 1 shows a perspective view of an abalone cultivation container for use in an abalone farming arrangement according to the preferred embodiment of the present invention;

FIGURE 2 shows a side view partial cut away of the nets using in the abalone farming arrangement of Figure 1;

FIGURE 3 shows a top view of the nets used in the abalone farming arrangement of Figure 1;

FIGURE 4 is a close up view of the net of Figure 3;

FIGURE 5 shows a top view of the abalone farming arrangement of Figure 1;

FIGURE 6 shows a side view partial cut away of the abalone farming arrangement of Figure 1;

FIGURE 7 A, 7B, 7C and 7D are side views of abalone cultivation containers according to other embodiments of the invention;

FIGURE 8 shows a perspective view of the abalone habitats; and

FIGURE 9 is a cross-section of the container showing the abalone habitats over the cultivating region.

DESCRIPTION OF PREFERRED EMBODIMENT Wild abalone, such as greenlip abalone, spawn in the southern hemisphere between August and November. Adult abalone are induced to spawn primarily by using temperature shock technique or other means as necessary. Spawning is conducted in a hatchery and the larvae allowed to develop in an environment conditioned to mimic the natural environment. An ongoing supply of abalone is produced by this spawning and hatchery technique.

The juvenile abalone are maintained in an artificial nursery for 6 months and are fed on a microalgae diet. After 6 months the immature abalone are graded for size and those which have reached a certain size, are transferred to a cultivating container in a body of water such as the ocean. Essentially the culturing of abalone in this embodiment consists of three stages, hatchery, nursery and grow-out. The grow-out period is performed in a cultivating cage or cultivating container located in the ocean. The offshore location of the container in the ocean is selected so as to optimise abalone development. A good site is characterised by a body of water having:

• consistent water tidal flow;

• having sufficient water depth;

• being in relatively sheltered offshore waters;

• having a water temperature which is suitable to the grow-out of abalone;

• being remote from urban development;

• being clean and free from pollutants, or the risk of pollutants.

One suitable region of the Australian coastline in Southern Australia is located adjacent to the coastline approximately 15 kilometres to the south east of the town of Ceduna, South Australia, in the region known as Cape D'Estrees at which there are a number of suitable locations for positioning one or more cultivating containers.

Allowing the grow-out period for the abalone to occur in the natural environment of the ocean has the benefit of reducing stress to the animal by minimising handling during the all important grow-out period. The abalone is exposed to normal sea conditions yet are protected from predators by the container structure thereby maximising abalone yield. Harvesting occurs when the abalone has matured and the abalone has a shell size of between 70- 100mm or at approximately 3-4 years of age, dependant upon market demands.

The abalone reside in a cultivating region of the container. This region may be the base of the container or it may be a level or platform disposed above the base of the container as desired. The region can be flat or curved (bowl- shaped) or the region can have undulations.

While in the container, the abalone are able to feed on algae which collect and grow on the surfaces of the container and other structures located within the container. Preferably structures are disposed in the container so as to optimise algae productivity therefore providing a natural food source to the abalone.

This is discussed further below. In order to induce and promote the growth of algae, the flow of current(s) and/ or tidal flow within the container is regulated by a water flow control arrangement. The water flow control arrangement ensures that the flow of water is slower over the cultivation region of the container than higher above the cultivating region of the container. This permits algae to settle on the cultivating region and to proliferate before the tidal flow or water currents can dislodge and wash the algae away. It also allows any algae which rubs off onto the cultivating region to settle for abalone to consume.

Figure 1 depicts an abalone farming or cultivating container floating in the ocean. The container is supported by a buoyant support arrangement which provides buoyancy to the cultivating container. In the preferred embodiment, the buoyant support arrangement is two circular inflated tubes or pipes. The pipes have side walls which depend from the pipes and connect with a base. The side walls have apertures which are graduated in size towards the cultivation region of the container. In Figure 1 the cultivation region is the base of the container. The smaller apertures toward the base reduce current or tidal flow by impeding water flow though the container, hence, water flows more slowly over the cultivation region of the cage than higher above the cultivation region.

In addition to concerns regarding flow, the depth of the container is chosen, so as to optimise the photosynthetic processes of the algae settling on the side walls, the base of the container as well as structures within the container, the algae thereon establishing themselves and growing. The depth of the container will depend upon water clarity and sea conditions. The type of algae will vary from site to site and the target algae species will vary for the different abalone species. In general the target algae species are

Rhodoyphytes (also called red algae), Phaeophyta (also called brown algae) and Chlorophyta (also called green algae).

Prior to the introduction of abalone, the container and all structures within the container such as the nets and habitats (discussed below) are placed for 2-4 months in offshore waters having algae within the water. Once there is adequate coverage of algae on and in the cultivating container, the nursery abalone are introduced into the container for cultivation. While the abalone reside in the container there is a continual build up of algae on and in the cultivating container. Algae is the primary food source for the abalone therefore the abalone do not need to be fed manufactured or introduced natural feed, such as pellets or kelp, etc. This means the container of the present invention is less labour and resource intensive than prior arrangements. Abalone are introduced at a density that will not require relocation of the abalone as they grow. Preferably initial and on-going algae growth is in excess of abalone consumption of the algae in the first 2 years, therefore the algae will be established sufficiently to sustain the abalone throughout the third and fourth year of abalone residence.

Referring to Figure 1, there is shown an abalone farming arrangement comprising a cultivating container 10 floating in a body of water 11. In this case, the body of water is the ocean having water flow. The flow may be tidal flow or currents within the water. The cultivating container 10 houses abalone 12 which are sustained by the growth of algae 14 that colonise on the container 10 surfaces. The container itself is not buoyant and floats at the ocean surface with the aid of flotation devices, preferably in one embodiment being two 400mm polypropylene tubes 16a and 16b. The first tube 16a has a diameter of 20m-40m and supports the external wall of the container 10 whilst

the second tube 16b, which floats inside the area formed by the first tube 16a, has a diameter of 10m-20m and supports the inner wall of the container 10.

It should also be understood that flotation of the container can be effected by any suitable means, for example, a plurality of independent buoys rather than annular tube(s). It is an option that these independent buoys be joined together by a rigid ring to improve shape integrity to the top surface of the container 10. It should also be understood that the buoys can be partially filled with water and that the container buoyancy can be adjusted by adding or discharging water ballast.

In a preferred embodiment the container is annular in plan view with a diameter of 20m - 40m and depends to a depth of 3m-7m. It should be understood that the container can have any shape in plan view, the outer dimensions of which allow abalone to reside within the container, and can depend to any depth in which algae growth upon the container will occur. For example, the container can be circular instead of annular and have only one flotation device e.g. a polypropylene tube for support in the ocean. The container can also be square, triangular, etc. The inner base of the container is preferably flat but other shapes are possible.

The top 17 of the annular container 10 is open thereby improving the amount of sunlight into the container and promoting the movement of water through the container 10. The container has at least one side wall 20. In the case of a cylindrical container, there is one side wall. The preferred annular shape depicted in Figure 1 has two side walls (one cylinder disposed within the other). Side walls 20 includes apertures within at least a portion of the walls 20 to control the flow of water through the container. For example, the side walls may be a rigid material such as a plastic having apertures in the plastic.

In the preferred embodiment, however, the sides 20 of the container 10 are made from a 3-7m length of 15mm nylon mesh 18. The mesh 18 is secured to the polypropylene tubes 16a and 16b by ropes (not shown). It is an option that the mesh forms a portion of a side wall (the mesh supported, for example, by a rigid frame), however, the flow of water within the container will be better regulated if all of the side walls are formed from mesh.

To further promote and provide a convenient structure for the growth and delivery of algae to the abalone within the container, particularly the growth of Chlorophyta (or green algae), supports are strung radially within the annular container at sea level to support one or more structures for inducing, encouraging or promoting algae growth. In the preferred embodiment the supports are ropes 21. It is an option that the ropes are maintained at sea level by floats. Ropes 21 support one or more structures such as netting or nets 23 which are draped over ropes 21 so that the nets depend into the annular cultivating container above the cultivation region. The structures can be nets or any other structure which acts to promote or induce algae growth such as lengths of rope or pieces of shade cloth. In Figure 1 four ropes are shown strung over the container. It will be understood that any number of ropes could be used. Only one net 23 is shown in Figure 1 for clarity, however, each rope could have a net depending from it into the container.

Figure 2 is a side view of the nets in the container. The depth to which nets 23 depend into the container may vary. Nets 23 are made from nylon, however, the nets may be made from any material suitable for growing algae on, for example, polyester or other durable fibres such as Manila hemp, etc. The nets have a mesh construction which is similar or the same as the mesh at the top level of the sides 20 of the container.

Figure 3 is a top view of ropes 21 supporting nets 23. Figure 4 shows that preferably each net is hung with approximately half on one side and the other half on the other side of rope 21. The net is then tied to rope 21 to secure it in place. This ensures that the net does not shift or fall off the ropes due to wave motion and/ or rough seas. Any method which secures the nets to the ropes could be used, for example, clips.

The depending nets 23 become a growing environment for algae since the nets are close to the surface and in the flow of algae that flows into the container. In rough seas and/ or when the net halves rub together, the algae which have established on the net rubs off the net and falls onto the abalone growing area below (cultivation region).

The mesh 18 of the side walls depends, in this embodiment, approximately 3- 7 m into the water and is then connected to the cultivation region 22 (in this case the cultivation region is also the base of the container). The central column 24 is formed by a mesh side wall depending from the tubes 16a and 16b. Column 24 is said to increase water flow through the cultivating container 10.

The mesh is adapted to control the flow of water in the cultivating container since the apertures in the mesh 18 are graduated in size to the cultivation region 22. For example 100 mm apertures at the top of the container graduating to 14 mm-16 mm apertures at the cultivation region. The aperture size may decrease gradually, or the aperture size may decrease by way of bands of mesh, each band having apertures of smaller dimensions. This decrease in aperture size acts as a water flow control arrangement; controlling the flow of water which passes through the cultivating container and over the cultivation region upon which the abalone reside. Effectively, the smaller

apertures at the base of the container decrease water flow and permit algae to proliferate at the base. Furthermore, the decreased flow at the base of the container ensures that algae which rubs off nets 23 and falls onto the base is not washed out of the container by natural tidal or current flows.

The cultivation region 22 (and/ or the base if separate from the cultivation region) is attached (preferably removably attached) to at least one of side walls 20. When in use, the cultivation region 22 is joined by sewing it directly to the mesh 18 forming the side walls 20. Any method of connecting the base and the side walls could be used. Alternatively the base and side walls may all be formed from one piece of material. The cultivation region 22 is preferably made of mesh in which the apertures are so small that the base is almost an enclosed surface (for example, finely knit shade mesh e.g. shade cloth). This provides a substantially solid but flexible base over which the abalone can move. Abalone habitats 30 can be placed on the cultivation region 22 of the container 10, in one example evenly spaced from one another.

The container 10 is secured to the bottom surface of the ocean 24 by lines 26 and anchors 28. The anchors 28 are 600kg AlO Danforth type with 700mm flukes that sink directly into the sea bed. The anchors 28 have lines 26 attached to them, the lines being 6m of 32mm stud link chain which links onto 30m of 40mm 8 plat Super Dan (polypropylene) rope. The rope is secured to a 200L float (not shown) and then to the container 10, using a 5m V-bridle (not shown). The skilled addressee will understand that any suitable means for anchoring the container 10 could be used. The anchor and chain size and length is determined by site conditions and sea bed type.

Turning now to Figure 5, the container 10 of Figure 1 is seen from the top view. The annular shape of the container 10 can be seen to be formed by the

two polypropylene tubes 16a and 16b. The cultivation region 22 is enclosed while the column 24 area is open to the surrounding sea and, at the top, air. Ropes 21 and nets 23 are omitted from this figure. In Figure 6, the container 10 of Figure 1 is seen from the side view. The annular shape of the container 10 can be seen to be formed from mesh 18, which depends from the two polypropylene tubes 16a and 16b, to a depth of approximately 4m. The cultivation region 22, upon which the abalone reside, can be seen in this Figure. The abalone habitats 30 are removable and movable and are positioned upon the cultivation region 22. In Figure 6 it can be seen that the mesh 18 which is joined to the polypropylene tubes 16a and 16b is not pulled tight at the top 17, rather the mesh is slack and is only secured at 2-3m intervals 31. This loose attachment means that debris such as seaweed will not get caught on the mesh 18 but rather will flow through the container, and pass out the other side at the water surface level. Again, for clarity, ropes 21 and nets 23 are omitted from this figure.

It is an option that the mesh wall(s) of the container do not depend directly from the buoyant tubes 16a and 16b but rather there are ropes extending from one or more buoys at the surface and which support mesh walls below the water surface. An example of this arrangement is shown in Figure 7a; tube 16a floats at the surface of the water (and may be an independent buoy rather than an annular tube if desired), ropes depend from tube 16a to join with tube 16b and tube 16c. Mesh wall 18 depends from tube 16b to tube 16c, there being an open area between tube 16a and 16b. This arrangement also ensures that debris such as seaweed will not get caught on mesh 18 but rather will flow through the cultivating container, and pass out of the other side of the container at the water surface level. Further alternative cultivating container arrangements deemed to be within the scope of the invention are shown in Figures 7b, 7c and 7d. In 7a and 7b the container is supported from ropes

depending from buoys. In 7ά the mesh side walls of the container depend from buoys and form a cultivating region at the base.

Figure 8 shows a close up of an array of abalone habitats 30. The abalone habitats are elongate moulded poly-plastic structures with a plurality of troughs and peaks. The habitats 30 are approximately 30 cm in height and are secured by ropes to the cultivation region 22 of the container 10 (not shown). Securing the habitats ensures that the habitats are stable with respect to cultivation region 22 for abalone to attach and move about on while growing. It should be understood that Figure 8 shows one shape of artificial habitats and that other shapes could be usefully employed. Furthermore, it is a preferred option that cultivation region 22 has mesh pockets, the pockets secured to the base by clips (in the preferred embodiment snap clips), into which habitats 30 can be disposed to provide further stability to the habitats. The pockets ensure that the habitats 30 cannot move with respect to the cultivation region.

Figure 9 is a cross-section showing the arrays of abalone habitats disposed within mesh pockets 38 over the cultivating region 22. (Referring back to Figure 1, abalone habitats 30 are shown over a portion of the cultivating region 22 and it will be understood that they can cover the entire cultivating region 22). The purpose of the habitats 30 is to simulate the natural environment of abalone, allowing the abalone to crawl and attach themselves over the top of the habitats 30 as well as move and attach themselves underneath the habitats 30 in darker areas. Referring back to Figure 8: each habitat has a top section or peak 32 in which there are a plurality of slots 34. The slots are wide enough such that the abalone 12 can move through the slots if they desire to reside in a darkened environment, shielded by the walls of the habitats 30. Alternatively the abalone 12 can reside between adjacent

habitats 30 in a trough 36 formed by any two habitats 30. The size and shape of the habitats 30 may vary. The abalone move about the habitats 30 as they seek food (e.g. algae) and different light conditions. The reduced water flow over the base (reduced by the water flow control arrangement (in this case apertured side-walls)) ensures that the abalone can move about the cultivating region 22 and habitats 30 without being impeded or dislodged by water flow.

The abalone farming arrangement described above is more environmentally friendly than current farming techniques. Structures such as ropes and nets are placed in the container to encourage the growth of algae, particularly Chlorophyta (also called green algae) (but also red and/ or brown algae in some cases), which provides a constant natural food source to the abalone. Feeding becomes self-regulated with the container being colonised with a sustainable number of abalone per m ² of feed production area so as to allow the abalone to grow from spat to harvest without need to disturb the stock. To reduce the number of unwanted weeds and unwanted algae which grow in the container and encourage the growth of preferred weeds and preferred algae, the containers can be control-weeded by divers. Most of the weed and algae will populate nets 23.

The area of nets 23 over which algae will grow will vary depending upon the diameter of the container. A container having a diameter of 40 metres will preferably have approximately 6100 m ² of nets depending into the container. Such a container would also preferably have approximately 2500 m ² of a habitat 30 surface area, on and in which the abalone will live. A container is generally stocked with 16 abalone per m ² of artificial habitat area and/ or 5 abalone per m ² of netting available for producing feed in the form of algae.

The container is also able to withstand changing environmental conditions and can therefore be located in more exposed off-shore sites than current farming arrangements. Mature abalone are selected and then removed or harvested from the cultivating container once they are ready for consumption. Abalone which are selected are generally those which can be sold, for example, as small as 50 mm or as large as 200 mm. Preferably abalone are sold in the third or fourth year of cultivation, the shell size being approximately 70 mm or the in shell weight being 50 g (the size and weight measured in accordance with standard practices known to the person skilled in the art).

Overall the arrangement may produces larger volumes of abalone over a shorter period of time with lowered per unit production costs under intensive aquaculture conditions. The abalone that are produced are larger which are more attractive in the international markets. The present arrangement also operates at lower capital and operating costs than on-shore operations and provides consistent growth rates and reduced problems associated with disease compared to on-shore operations since the abalone are grown in the ocean rather than an artificial onshore environment.

Although a preferred embodiment of the apparatus of the present invention has been described in the foregoing detailed description, it will be understood that the invention is not limited to the embodiment disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the invention. Modifications and variations such as would be apparent to a skilled addressee are deemed within the scope of the present invention.