WO2024123187A1

WO2024123187A1 - Aquaculture system for raising aquatic organisms and method of raising aquatic organisms

Info

Publication number: WO2024123187A1
Application number: PCT/NO2023/060116
Authority: WO
Inventors: Kåre Olavson Hæreid
Original assignee: Fjordmerd As
Priority date: 2022-12-06
Filing date: 2023-12-06
Publication date: 2024-06-13
Also published as: NO347982B1; NO20221306A1

Abstract

An aquaculture system (100) for raising aquatic organisms, comprising: a first rigid rearing unit (111) comprising a substantially watertight wall (112) and a substantially watertight base (112'), the substantially watertight wall (112) and substantially watertight base (112') forming a containment region for containing water and aquatic organisms within in use; a first rigid buoyancy cell (141) configured to provide buoyancy to the aquaculture system (100); and a water processing room (170) comprising a first pump configured to pump water from outside of the aquaculture system (100) to the containment region; wherein the first rigid rearing unit (111), first rigid buoyancy cell (141) and water processing room (170) are constructed in a monohull construction.

Description

AQUACULTURE SYSTEM FOR RAISING AQUATIC ORGANISMS AND METHOD OF RAISING AQUATIC ORGANISMS

FIELD

The present invention relates to a system and method for raising aquatic organisms. More specifically, the present invention relates to a fish farming system and a method for maintaining fish within a closed enclosure at a point in open water.

BACKGROUND

It is common to farm fish at sea in fish pens. Typically, the fish pens comprise a floating member that encircles an enclosure. Most commonly, the enclosure is formed by a net such that water can pass through the enclosure but the fish remain contained inside. After the fish have grown to a sufficient size, they are harvested. When the nets are empty of fish, they are removed and are often replaced for the next cycle of fish. The floating members are cleaned at sea before the new nets are attached.

Fish pens with a closed enclosure are an alternative to the above-described open nets. The closed enclosure is formed by a watertight material, thereby stopping water from passing freely through the enclosure in use. In some cases the watertight material is a flexible material. In some cases the watertight material is a rigid material such as, for example, steel or concrete. A closed enclosure may be provided as a mitigating measure against salmon lice. When using a closed enclosure, the provision of water to the fish pen can be controlled.

Fish pens with a closed enclosure require a water handling system for recycling water in the enclosure. A typical water handling system may comprise one or more pumps, and water treatment systems. These components may typically be placed on an outer wall of an enclosure, where the components may be difficult to access when service or maintenance is required. Components of the water handling system may also typically be placed on an exposed deck surrounding the enclosure, where the components may be exposed to harsh weather and sea water. This may lead to more frequent service or maintenance of the components positioned on the deck.

Construction of closed enclosures for fish pens is a demanding task that often requires dedicated yards and specialised vessels. In some instances it may even be required to fabricate the pen far away from the site at which it will be used, thus requiring great transportation costs. Modularly constructed fish pens exist. However, the fish pen ultimately must be assembled onshore and towed out to sea or assembled on a vessel. Towing an assembled fish pen is time consuming and expensive. Lifting an assembled fish pen from a vessel on which it is assembled requires a vessel and crane with a large lifting capacity. Such vessels are expensive and may need to be brought to remote locations specially to perform the lift, therefore there can often be a delay when such a vessel is required, otherwise the cost of having one on standby is extremely high.

There is a constant drive to reduce energy consumption in all industries. Some aspects of aquaculture can be energy intensive. There is a need to develop floating aquaculture facilities for breeding ready-to-slaughter fish with minimal energy requirements.

In the design of the fish pens, there is a need to establish large volumes for farming of the fish whilst establishing effective buoyancy volumes to ensure the fish pen does not sink.

Fish pens must also be designed such that they minimise the expose of the fish to lice or bacteria. Infectious Salmon Anemia (ISA) is often problematic in salmon farming.

Patent document NO343173B1 discloses a fish pen utilising a vertical riser and pump that directs water into a closed cage.

Patent document W02022/186700A1 discloses an aquaculture system for raising aquatic organisms, the aquaculture system comprising a plurality of rigid receptacles and a rigid central unit provided with a plurality of arms. Each receptacle comprises a watertight rigid wall and a watertight rigid bottom. A method for adjusting the vertical positions of the components in the system is also described.

Patent document NO344977B1 discloses a method for assembling a fish pen. The fish pen comprises a bottom unit having a buoyancy exceeding its weight and being fabricated as one solid element with an impermeable body. The bottom unit comprises one or more buoyancy elements having a controllable buoyancy. The fish pen further comprises at least one impermeable wall element. The method comprises providing the bottom unit on a surface of a water body, connecting the wall element to the body, altering the draught of the bottom unit and the at least one wall element connected to the body by controlling the buoyancy of the one or more buoyancy elements.

Patent document GB2068847 discloses a plurality of rectangular buoyancy elements made of concrete, which are held together by a wire or chain. The wire or chain extends through flush, elongated channels inside the buoyancy elements. In their adjacent end faces, the elements are formed with recesses at the mouths of the channels. A spacer consisting of an elastic material is positioned in the recesses of the two adjacent end faces between two neighbouring buoyancy elements. The spacer is provided with a through bore for the wire or chain. The elastic spacer absorbs longitudinal forces so that neighbouring elements will not collide, counteracts relative vertical and horizontal lateral movements between two neighbouring elements, while, at the same time, it allows a certain degree of twisting and rotation between two neighbouring elements.

Patent document WO2016/039632 discloses a buoyancy system of modular construction for a cage. The modules are relatively large. Each module has a curved side facing in towards a circularly shaped cage. According to the description, the surrounding buoyancy system may comprise six, eight or ten modules. The modules may advantageously be made from concrete, especially reinforced concrete.

Patent document NO342556 discloses a floating arrangement for breeding fish and shellfish. The arrangement comprises an elongated cylinder element and a framework attached to the cylinder element and configured to define a cage for the fish and shellfish around the cylinder element. The cylinder element is configured with a buoyancy that constitutes a main portion of the buoyancy of the floating arrangement.

Patent document WO2018/156027A1 discloses a floating farm for rearing an aquatic organism. The farm comprising at least three rigidly connected rearing units, each rearing unit being surrounded at its upper portion by a continuous wall formed of a rigid material. The continuous wall forms a floating body, at least in a portion, and the continuous wall of a first rearing unit and the continuous wall of a second rearing unit are rigidly connected to a connecting wall formed of a rigid material, the connecting walls between the at least three rearing units together with the rearing units, seen from above, forming a triangular shape, a rhomboidal shape or a pentagonal shape.

Patent document NO166511 discloses a semi-submersible fish farm. The farm includes a deck resting on a plurality of buoyancy columns. At their bottoms, the buoyancy columns are resting on a bottom frame. The bottom frame may be formed as a box structure made of reinforced concrete. The bottom frame may be provided with buoyancy means. The farm is raised and lowered in the sea by adjusting the buoyancy of the buoyancy columns. The farm is a semi-submersible farm. The farm comprises a plurality of tanks or silos for rearing fish. The tanks have watertight walls and watertight bottoms. Water flows in and out of the tank through closable openings in the wall. The tanks may consist of steel, plastic or concrete. The tanks extend through openings in the deck and in the bottom frame, and the tanks project downwards and beyond the bottom frame.

The invention has for its object to remedy or to reduce at least one of the drawbacks of the prior art, or at least provide a useful alternative to prior art.

The object is achieved through features, which are specified in the description below and in the claims that follow.

SUMMARY

According to a first aspect of the invention, there is provided an aquaculture system for raising aquatic organisms, comprising: a first rigid rearing unit comprising a substantially watertight wall and a substantially watertight base, the substantially watertight wall and substantially watertight base forming a containment region for containing water and aquatic organisms within in use; a first rigid buoyancy cell configured to provide buoyancy to the aquaculture system; and a water processing room comprising a first pump configured to pump water from outside of the aquaculture system to the containment region; wherein the first rigid rearing unit, first rigid buoyancy cell and water processing room are constructed in a monohull construction.

The first rigid rearing unit, first rigid buoyancy cell and water processing room may be constructed of concrete or reinforced concrete or steel.

Although it is advantageous that the first rigid rearing unit, first rigid buoyancy cell and water processing room are constructed in a monohull construction, the first rigid rearing unit, first rigid buoyancy cell and water processing room may in another example be constructed as separate modular pieces which may be assembled together.

The aquaculture system may further comprise second and third rigid rearing units and second and third rigid buoyancy cells, wherein the second and third rigid rearing units and second and third rigid buoyancy cells are part of the monohull.

The second and third rigid rearing units and second and third rigid buoyancy cells may be formed of concrete or reinforced concrete or steel.

The aquaculture system may be configured to float in a body of water creating a water line on the external surface of the aquaculture system in use, wherein the first pump is configured to be located at a position below the water line in use.

The water processing room may be arranged to be directly above the water in which the aquaculture system floats in in use.

The first pump may be located within a first riser, the first riser extending from the water processing room substantially vertically downwards, such that in use the first pump can pump water from below the water processing room through the first riser and into the containment region.

The aquaculture system may further comprise a second riser in the water processing room, the second riser being configured to deliver water from below the water processing room into the containment region, wherein the first and second risers are arranged to deliver water to the containment region at different vertical locations in the containment region.

The first pump may be arranged to pump water through a first water treatment device before the water enters the containment region.

The first water treatment device may comprise one or more of: UV-radiation system; a filter; a water cleaning system; a water purification system.

The first rigid buoyancy cell may be configured to receive ballast water in use, such that the buoyancy provided by the first rigid buoyancy cell to the aquaculture system can be selectively reduced.

The first rigid buoyancy cell may comprise an upper portion and a lower portion, wherein the upper portion comprises a buoyancy cell treatment room and the lower portion comprises a buoyancy means.

The buoyancy means may be air.

The buoyancy cell treatment room may comprise a second pump fluidly connected to the containment region and configured to pump fluid from the containment region to outside of the aquaculture system.

The aquaculture system may be configured to float in a body of water creating a water line on the external surface of the aquaculture system in use, wherein the second pump is configured to be located at a position below the water line in use.

The second pump may be arranged to pump water through a wastewater treatment unit before the water is delivered to outside of the aquaculture system.

The wastewater treatment unit may comprise one or more of: UV-radiation system; a filter; a water cleaning system; a water purification system.

The first rigid rearing unit may comprise a sluice configured to be moveable between a closed configuration and an open configuration, wherein in the closed configuration the sluice does not allow fluid communication between the containment region and the body of water within which the aquaculture system floats, and in the open configuration the sluice allows fluid communication between the containment region and the body of water within which the aquaculture system floats such that water within the containment region can be drained through the sluice.

The sluice may comprise a grating cover configured such that when the sluice is in the open configuration such that water can flow through the sluice, aquatic organisms within the containment region cannot pass through the sluice.

The sluice may comprise a closing member and a biassing means configured to bias the closing member towards the closed configuration.

The biassing means may be configured such that a differential hydrostatic pressure across the closing member can move the closing member from the closed position to the open position against the bias of the biassing member, thereby allowing water to flow through the sluice.

According to a second aspect of the invention, there is provided a method of raising aquatic organisms, comprising the steps of: providing an aquaculture system according to the first aspect of the invention; floating the aquaculture system in a body of water; providing aquatic organisms and water in the containment region; and operating the first pump to pump water from the body of water outside of the aquaculture system to the containment region to maintain sufficient oxygen and/or a low carbon dioxide level in the containment region for the aquatic organisms to survive.

According to a third aspect of the invention, there is provided a method of raising aquatic organisms, comprising the steps of: providing an aquaculture system according to the first aspect of the invention; floating the aquaculture system in a body of water; providing aquatic organisms and water in the containment region; and operating the first pump to pump water from the body of water outside of the aquaculture system to the containment region to maintain sufficient oxygen and/or a low carbon dioxide level in the containment region for the aquatic organisms to survive; and operating the second pump to pump water from the containment region to outside of the aquaculture system to dispose of used water.

According to a fourth aspect of the invention, there is provided a method of raising aquatic organisms, comprising the steps of: providing an aquaculture system according to the first aspect of the invention; floating the aquaculture system in a body of water; providing aquatic organisms and water in the containment region; and operating the first pump to pump water from the body of water outside of the aquaculture system to the containment region to maintain sufficient oxygen and/or a low carbon dioxide level in the containment region for the aquatic organisms to survive and to provide a hydrostatic pressure differential across the sluice thereby moving the sluice to the open configuration such that used water drains from the containment region through the sluice.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described with reference to the following drawings, in which:

Figure 1 shows a floating farm for rearing fish;

Figure 2 shows an alternative view of the floating farm of Figure 1;

Figures 3a-3e show plan views of alternative configurations of the floating farm of Figure 1 ;

Figure 4 shows a cross-sectional view through the floating farm of Figure 1;

Figure 5 shows an alternative view of the floating farm of Figure 1;

Figure 6 shows a detailed view of risers within the floating farm of Figure 1;

Figures 7 and 8 show cross-sectional views through the floating farm of Figure 1; and

Figure 9 shows a detailed view of a sluice of the floating farm of Figure 1.

For clarity reasons, some elements may in some of the figures be without reference numerals. A person skilled in the art will understand that the figures are just principal drawings. The relative proportions of individual elements may also be distorted.

DETAILED DESCRIPTION OF THE DRAWINGS

Figures 1 and 2 show a floating farm 100 for rearing fish. Throughout the present description the term “fish” is used, and is intended to broadly refer to fish, crustaceans, shellfish or any other aquatic creature or organism which may be grown or reared in a fish pen. The floating farm 100 is shown partially submerged in water 1 with the water line being cut-away in Figure 1 to reveal the below-water portion of the floating farm 100. The floating farm 100 is shown in Figure 2 without the water-line for clarity.

The floating farm 100 comprises a plurality of rearing units 110. The plurality of rearing units 110 comprise first 111, second 121 and third 131 rearing units. Although in the presently described example three rearing units 111, 121 , 131 are provided, it will be understood that in alternative examples any number of rearing units may be provided with a substantially similar arrangement provided as is described herein.

Each rearing unit 111 , 121, 131 is formed of a hollow cylindrical shape with an open top and a closed bottom. That is to say, each rearing unit 111, 121, 131 is of a shell construction and comprises substantially watertight cylindrical walls 112, 122, 132 and a substantially watertight base portion (not visible in Figures 1 and 2) such that in use each rearing unit 111 , 121 , 131 forms a containment region wherein fish can live and grow and receive food. It will be understood that although a cylindrical structure is preferred, the rearing units in other examples may be in other shape forms.

The containment region within each rearing unit 111 , 121 , 131 contains water in use, such that the fish can survive. The water in the containment regions within the rearing units 111 , 121 , 131 cannot freely pass through the watertight walls or base of the rearing units 111 , 121 , 131. On the contrary, water is delivered and relieved from the rearing units 111 , 121 , 131 in a controlled manner, as will be explained later.

Still referring to Figures 1 and 2, each rearing unit 111, 121 , 131 comprises a net structure 113, 123, 133 arranged across the open top of the rearing units 111, 121 , 131 to stop birds or other animals from entering the rearing units 111, 121, 131. It will be understood that the net structures 113, 123, 133 are removable to provide access to the rearing units 111, 121, 131.

The floating farm 100 further comprises a plurality of buoyancy cells 140. The plurality of buoyancy cells 140 comprise first 141 , second and third buoyancy cells (not visible in Figures 1 and 2). Although in the presently described example three buoyancy cells are provided, it will be understood that in alternative examples any number of buoyancy cells may be provided with a substantially similar arrangement provided as is described herein.

The described construction utilises circular concrete shells both to effectively establish large volumes for the rearing units 110 and to establish effective buoyancy volumes in the buoyancy cells 140. Reinforced concrete may also be used. Steel may also be used.

As is shown in the plan views shown in Figures 3a-3e, in alternative examples any number of rearing units and buoyancy cells may be provided.

For example, in Figure 3a there is provided a first alternative floating farm 100’ comprising a plurality of rearing units 110’ comprising four rearing units and a plurality of buoyancy cells 140’ comprising five buoyancy cells. As shown, the plurality of buoyancy cells 140’ may be partially around the outside of the floating farm 100’ and partially in the centre of the floating farm 100’. As in this first alternative floating farm 100’, there may be a mismatch between the number of rearing units 110’ and the number of buoyancy cells 140’.

In Figure 3b there is provided a second alternative floating farm 100” comprising a plurality of rearing units 110” comprising three rearing units and a plurality of buoyancy cells 140” comprising three buoyancy cells. As in the second alternative floating farm 100”, there may be a match between the number of rearing units 110” and the number of buoyancy cells 140”.

In Figure 3c there is provided a third alternative floating farm 100’” comprising a plurality of rearing units 110’” comprising four rearing units and a plurality of buoyancy cells 140’” comprising nine buoyancy cells.

In Figure 3d there is provided a fourth alternative floating farm 100”” comprising a single rearing unit 110”” and a plurality of buoyancy cells 140”” comprising four buoyancy cells.

In Figure 3e there is provided a fifth alternative floating farm 100’”” comprising a plurality of rearing units 110’”” comprising two rearing units and a plurality of buoyancy cells 140’”” comprising six buoyancy cells.

As in the third, fourth and fifth alternative floating farm 100’”, 100””, 100’””, there may be a greater number of buoyancy cells 140’”, 140””, 140’”” compared to rearing units 110’”, 110””, 110’””.

The floating farm 100 is arranged to allow the containment of fish for the purposes of any of one or more of the following: breeding; feeding; growing; storing and/or protecting, or any other activity whereby it is desired to contain fish within a fixed containment region for a period of time. Most typically, the floating farm 100 may be used for breeding ready-to-slaughter fish with minimal energy needs, as will be described later.

Referring now to Figure 4, features of the floating farm 100 shown in Figures 1 and 2 are now described in more detail. Figure 4 shows a cross-sectional cut through the floating farm 100, through the first rearing unit 111 and second buoyancy cell 151. In this view the watertight wall 112 and base portion 112’ of the first rearing unit 111 can be seen.

As previously discussed, the plurality of rearing units 110 are not open at the bottom to the water within which the floating farm 100 is floating. Similarly, the plurality of buoyancy cells 140 are also not open at the bottom to the water within which the floating farm 100 is floating. The buoyancy cells 140 may comprise a buoyancy means. The buoyancy means may simply be air. The buoyancy cells 140 may be selectively partially or completely filled with water during use, thereby reducing the buoyancy effect of the buoyancy cells 140 and increasing the draft of the floating farm 100, as will be explained later.

Still referring to Figure 4, located centrally in the floating farm 100 between the plurality of rearing units 110 and the plurality of buoyancy cells 140 there is provided a water processing room 170 and there below an open portion 180. Although not shown in Figure 4 in the interest of clarity, the water processing room 170 comprises water pumping and/or processing and/or cleaning equipment, as will be explained later. It can be seen in Figure 4 that the water processing room 170 comprises a lowermost deck 171 and an uppermost deck 172 forming the lower and upper extremities of the water processing room 170. The lowermost deck 171 forms the boundary between the water processing room 170 and the open sea.

Open sea is used herein to refer to the body of water within which the floating farm 100 is floating. It will be understood that if the floating farm is used in a lake, reservoir, fjord or other body of water, open sea is intended to mean that body of water. In this connection, the open sea may fill the open portion 180 located below the lowermost deck 171.

It will be appreciated that, when floating in a body of water in use, the external water level will be higher than the water level within the open portion 180. Said another way, the water in the open portion 180 will come up to the lowermost deck 171, whereas on the outside of the floating farm 100, the external water level will be higher than in the open portion 180.

In the presently described example, the first rearing unit 111 may be around 33.4 meters in the longitudinal direction of the cylinder. The water processing room may have a height of around 7 meters and the open portion may have a height of around 26.4m. It will be appreciated that the dimensions may vary dramatically in alternative examples and the dimensions given herein for the preferred example are non-limiting and provided for exemplary purposes only.

Referring now to Figure 5, the floating farm 100 is shown with the rearing units 110 hidden to improve clarity. In this connection, Figure 5 shows first 141, second 151 and third 161 buoyancy cells and components located within the water processing room 170. Again, in the interest of clarity, only the lowermost deck 171 of the water processing room 170 is shown in Figure 5.

As can be seen in Figure 5, the water processing room 170 is divided into levels by means of a truss/grating structure 173. The truss/grating structure 173 provides a raised level which can be walked upon or equipment can be located on, whilst still allowing access through the truss/grating structure 173 to equipment on the lower level.

Located in the water processing room 170 there are a plurality of vertical pumps (not shown) mounted within vertical risers 190. Although not shown in Figure 5, it will be appreciated that the first 111 , second 121 and third 131 rearing units are located between the first 141 , second 151 and third 161 buoyancy cells. In this connection, the first buoyancy cell 141 is located between the first 111 and second 121 rearing units, the second buoyancy cell 151 is located between the second 121 and third 131 rearing units and the third buoyancy cell 161 is located between the third 131 and first 111 rearing units.

There is provided a first 191, second 192, third 193 and fourth 194 set of risers, configured to convey water from the open portion 180 to the first rearing unit 111. A detailed view of the first set 191 of risers is shown in Figure 6.

The first set 191 of risers comprises a first riser 19T and a second riser 191”. The first 19T and second 191” risers are each arranged to convey water from the open portion 180 to the first rearing unit 111 through respective first and second water treatment devices 191’A, 191”A.

In the presently described example the first and second water treatment devices 191’A, 191”A are UV-radiation systems for treating the water immediately before it enters the first rearing unit 111. It will be understood that the water treatment devices 191’A, 191”A may additionally or alternatively provide other water treatment functions, such as, but not limited to, water purification, cleaning and/or filtering, or any other suitable water treatment function.

As can be seen in Figure 6, the first riser 19T is arranged adjacent the second riser 191”, with the first and second water treatment devices 191’A, 191”A being arranged such that they are vertically disposed. In this connection, the first water treatment device 191’A is located between the lowermost deck 171 and the truss/grating structure 173, and the second water treatment device 191”A is located above the truss/grating structure 173.

Referring again to Figure 5, it can be seen that the second 192, third 193 and fourth 194 sets of risers are arranged as described above for the first set of risers 191. Additionally, to provide water to the second rearing unit 121 , there is provided a fifth 195, sixth 196, seventh 197 and eighth 198 set of risers. Additionally, similar risers are provided to provide water to the third rearing unit 131 , however these are not marked on Figure 5 or described in detail here in the interest of clarity and brevity.

By locating the risers 190, pumps and water treatment devices 191’A, 191”A within the water processing room 170, the risers 190, pumps and water treatment devices 191’A, 191”A may be easily accessible from the water processing room 170 when it is required to service or maintain the risers 190, the pumps and/or the water treatment devices 191’A, 191”A.

The plurality of buoyancy cells 140 can be controlled in use such that the buoyancy provided by the plurality of buoyancy cells 140 can be adjusted, thus adjusting the draft of the floating farm 100. In this connection, it can be ensured that, in use, the pumps within the risers in the water processing room 170 are located below the external water level, thus reducing the power required to pump water from the open portion 180 to the rearing units 111 , 121 , 131. The buoyancy of the buoyancy cells 140 may be adjusted in a plurality of ways depending on the buoyancy means within the buoyancy cells 140. In the preferred example described herein, the buoyancy means is simply air. In this connection, the buoyancy is adjusted by filling or partially filling the buoyancy cells 140 with water, to lower the floating farm 100 into the water.

In the preferred example described herein, the rearing units 111, 121, 131 and buoyancy cells 141 , 151 , 161 and water processing room 170 are together formed of a monohull constructure. In the present context, monohull is intended to mean that the hull, i.e. the rearing units 111 , 121 , 131, buoyancy cells 141, 151, 161 and water processing room 170 are formed of a single continuous hull, rather than the floating farm 100 being formed of multiple modular pieces which are assembled together.

In another example (not shown) the rearing units 111, 121, 131 and buoyancy cells 141 , 151 , 161 and water processing room 170 are separate modular pieces which are assembled together. As such, a monohull construction is not required but may be advantageous in some applications.

For example, a monohull construction, may allow the provision of a floating farm with larger capacity rearing units 111 , 121 , 131 compared with a modular construction, though in some circumstances a modular construction may be preferable, for example due to ease of transportation.

Said another way, a floating farm 100 constructed as a monohull is manufactured in one main piece. It will be understood that minor components, such as the vertical risers 190, net structures 113, 123, 133 etc. are attached to the floating farm 100 after the main construction of the hull, i.e. the rearing units 111, 121, 131, buoyancy cells 141, 151, 161 and water processing room 170.

Figure 7 shows a cross-sectional view through the first rearing unit 111 , the open portion 180, the water processing room 170 and the third buoyancy cell 161. It can be seen that the cross-section cuts through the first riser 191’. It will be appreciated that other risers may be visible in this cross-sectional cut but are omitted from Figure 7 in the interest of clarity for the purposes of the following explanation. Referring to Figure 7, it can be seen that the first riser 19T reaches from the water processing room 170 into the open portion 180 (where the water level is up to the lowermost deck 171 of the water processing room 170). In this connection, it can be seen that the external water level 1 is higher than the water level within the open portion 180. It will be understood that water may be pumped from the open portion 180 to the first rearing unit 111 through the first riser 19T. The energy required to pump water from the open portion 180 through the first riser 19T as shown is low compared to the energy which would be required if the water had to be pumped above the external water level 1.

It can also be seen in Figure 7 that, to allow the floating farm 100 to sit at the operational position shown in Figure 7, the third buoyancy cell 161 has received some water to reduce the buoyancy effect of the third buoyancy cell 161 , thereby maintaining the floating farm 100 at the operational draft shown.

Still referring to Figure 7, the first rearing unit 111 is provided with a sluice 200 located near the bottom of the first rearing unit 111. The sluice 200 is configured to automatically release water from the first rearing unit 111 when there is a hydrostatic pressure differential across the sluice 200. As can be seen in Figure 7, the pump within the first riser 191 ’ has been operating to deliver water to the first rearing unit 111 , which has resulted in the water level within the first rearing unit 111 being higher than the water level 1 which the floating farm 100 floats in. The sluice 200 is therefore subjected to a greater hydrostatic pressure on the inside of the first rearing unit 111 at point A compared to the outside of the first rearing unit 111 at point B. The sluice 200 therefore releases used water from inside the first rearing unit 111 when fresh water is delivered to the first rearing unit 111 from the risers and pumps in the water processing room 170. The sluice 200 ensures that the water level within the first rearing unit 111 does not overflow the open top of the first rearing unit 111. Also, referring back to Figures 1 and 2, it can be seen that if the rearing units 111 , 121 , 131 were allowed to overflow, there may be a large volume of water delivered to a walking deck 101 , where personnel may walk or equipment/feed etc. may be stored. It is therefore highly preferable to automatically eject water to the surrounding sea from the sluice 200, when required, as described.

Although the term sluice is used herein, it will be understood that the sluice may be referred to by other terms in other examples, such as for example a self-closing gate or self-closing valve, or a one-way gate or one-way valve.

Figure 8 shows a cross-sectional cut through the first buoyancy cell 141 and the third rearing unit 131. In Figure 8 an alternative method of removing wastewater from the rearing units 111, 121, 131 is described. The alternative method may be used instead of or as well as providing sluices 200 as described above with reference to Figure 7. In the alternative method, the first buoyancy cell 141 is divided into two parts. An upper portion provides a buoyancy cell treatment room 141A and the lower portion provides a ballast water space 141 B. As shown in Figure 8, the ballast water space 141 B is partially filled with ballast water to adjust the buoyancy provided by the first buoyancy cell 141 , as previously explained. The buoyancy cell treatment room 141A is similar to the water processing room 170 in that it provides a dry and accessible space to provide water processing equipment. By providing this equipment in such a space, it can be easily accessed, serviced and maintained.

Still referring to Figure 8 it can be seen that the first buoyancy cell 141 is provided with a wastewater extraction system 300. The wastewater extraction system 300 comprises a port 301 located in the wall of the third rearing unit 131 , and piping connecting the port 301 to a wastewater treatment unit 302 and a pump 303 which are located in the buoyancy cell treatment room 141A. The pump 303 can be operated to extract wastewater from the third rearing unit 131 and deliver the water to the surrounding sea. The wastewater treatment unit 302 may comprise a UV-radiation system, a filter, a water cleaning system, or a water purification system. The wastewater can be cleaned by the wastewater treatment unit 302 before the water is delivered to the surrounding sea. The described wastewater extraction system 300 can be used instead of or alongside the above-described sluice 200.

It will be appreciated that using either the described sluice 200 arrangement or the wastewater extraction system 300, used water may be extracted to the periphery of the floating farm 100. It is advantageous to extract used water at the periphery of the floating farm 100 when water is delivered to the rearing units 111, 121, 131 from the centre of the floating farm 100. This ensures that the water extracted from the rearing units 111 , 121 , 131 is not recycled back into the rearing units 111 , 121 , 131.

The sluice 200 may be set to open at a particular differential pressure thereacross. Alternatively, or additionally, the sluice 200 may be configured to open when another parameter is reached. Alternatively, or additionally, the sluice 200 may be controllable by means of a control system. Alternatively, or additionally, the sluice 200 may be controllable by remote control and may be selectively openable by a technician when it is required to open the sluice 200. One example of when it may be required to open the sluices may be when the rearing units 111, 121, 131 are to be drained for cleaning or maintenance. It will be appreciated that although only one sluice 200 is described herein, each rearing unit 111, 121, 131 may comprise one or a plurality of such sluices 200.

If the rearing units 111 , 121, 131 are drained for cleaning or maintenance, the bottom of each rearing unit 111, 121, 131 may be cleaned by a robot, for example. The robot may be programmed to clean the particular shape of the bottom of each rearing unit 111 , 121 , 131 or may comprise cameras or sensors and a control system to detect the shape of the bottom of each rearing unit and effectively clean the rearing unit.

It will be appreciated that the floating farm 100 may contain many other pieces of equipment used in aquaculture. For example, although not specifically mentioned in the present description in the interest of brevity, the floating farm 100 may comprise feed storage and distribution equipment, water quality sensing equipment and chemical injection equipment, for example.

Referring now to Figure 9, further details of the sluice 200 are now provided. The sluice 200 is provided with a grating cover 210 arranged on the inside of the sluice 200 towards the inside of the rearing unit 111 , such that fish contained within the rearing unit 111 cannot escape through the sluice 200 when the sluice 200 is opened. It will be appreciated that the grating cover 210 comprises suitably sized holes such that water flow through the grating cover 210 is sufficient to allow the rearing unit 111 to be drained without allowing fish to escape. The sluice 200 further comprises a closing member 220 which is biased towards the closed position shown in Figure 9. The biassing is provided by a biassing member 230 in the form of a weight connected by a hinge 240. The weight 230 is selected to be appropriate to allow the hydrostatic pressure to push the sluice 200 open when it is required that the water flows out of the rearing unit 111 to ensure that the rearing unit 111 does not overflow, as previously described. It will be understood that biassing towards the closed position shown in Figure 9 may be provided in myriad different forms, which will be understood by a person skilled in the art.

Clauses

Clause 1 An aquaculture system for raising aquatic organisms, comprising: a first rigid rearing unit comprising a substantially watertight wall and a substantially watertight base, the substantially watertight wall and substantially watertight base forming a containment region for containing water and aquatic organisms within in use; a first rigid buoyancy cell configured to provide buoyancy to the aquaculture system; and a water processing room comprising a first pump configured to pump water from outside of the aquaculture system to the containment region.

Clause 2 The aquaculture system according to clause 1 , wherein the first rigid rearing unit, first rigid buoyancy cell and water processing room are constructed in a monohull construction.

Clause 3 The aquaculture system according to clause 1 or 2, wherein the first rigid rearing unit, first rigid buoyancy cell and water processing room are constructed of concrete or reinforced concrete or steel.

Clause 4 The aquaculture system according to any preceding clause, further comprising second and third rigid rearing units and second and third rigid buoyancy cells.

Clause 5 The aquaculture system according to clause 4, wherein the second and third rigid rearing units and second and third rigid buoyancy cells are part of the monohull.

Clause 6 The aquaculture system according to clause 4 or 5, wherein the second and third rigid rearing units and second and third rigid buoyancy cells are formed of concrete or reinforced concrete or steel.

Clause 7 The aquaculture system according to any preceding clause, wherein the aquaculture system is configured to float in a body of water creating a water line on the external surface of the aquaculture system in use, wherein the first pump is configured to be located at a position below the water line in use.

Clause 8 The aquaculture system according to any preceding clause, wherein the water processing room is arranged to be directly above the water in which the aquaculture system floats in in use.

Clause 9 The aquaculture system according to clause 8, wherein the first pump is located within a first riser, the first riser extending from the water processing room substantially vertically downwards, such that in use the first pump can pump water from below the water processing room through the first riser and into the containment region.

Clause 10 The aquaculture system according to clause 9, further comprising a second riser in the water processing room, the second riser being configured to deliver water from below the water processing room into the containment region, wherein the first and second risers are arranged to deliver water to the containment region at different vertical locations in the containment region.

Clause 11 The aquaculture system according to any preceding clause, wherein the first pump is arranged to pump water through a first water treatment device before the water enters the containment region.

Clause 12 The aquaculture system according to clause 11 , wherein the first water treatment device comprises one or more of: UV-radiation system; a filter; a water cleaning system; a water purification system.

Clause 13 The aquaculture system according to any preceding clause, wherein the first rigid buoyancy cell is configured to receive ballast water in use, such that the buoyancy provided by the first rigid buoyancy cell to the aquaculture system can be selectively reduced.

Clause 14 The aquaculture system according to any preceding clause, wherein the first rigid buoyancy cell comprises an upper portion and a lower portion, wherein the upper portion comprises a buoyancy cell treatment room and the lower portion comprises a buoyancy means.

Clause 15 The aquaculture system according to clause 14, wherein the buoyancy means is air.

Clause 16 The aquaculture system according to clause 14 or 15, wherein the buoyancy cell treatment room comprises a second pump fluidly connected to the containment region and configured to pump fluid from the containment region to outside of the aquaculture system.

Clause 17 The aquaculture system according to clause 16, wherein the aquaculture system is configured to float in a body of water creating a water line on the external surface of the aquaculture system in use, wherein the second pump is configured to be located at a position below the water line in use.

Clause 18 The aquaculture system according to clause 16 or 17, wherein the second pump is arranged to pump water through a wastewater treatment unit before the water is delivered to outside of the aquaculture system.

Clause 19 The aquaculture system according to clause 18, wherein the wastewater treatment unit comprises one or more of: UV-radiation system; a filter; a water cleaning system; a water purification system.

Clause 20 The aquaculture system according to any preceding clause, wherein the first rigid rearing unit comprises a sluice configured to be moveable between a closed configuration and an open configuration, wherein in the closed configuration the sluice does not allow fluid communication between the containment region and the body of water within which the aquaculture system floats, and in the open configuration the sluice allows fluid communication between the containment region and the body of water within which the aquaculture system floats such that water within the containment region can be drained through the sluice.

Clause 21 The aquaculture system according to clause 20, wherein the sluice comprises a grating cover configured such that when the sluice is in the open configuration such that water can flow through the sluice, aquatic organisms within the containment region cannot pass through the sluice.

Clause 22 The aquaculture system according to clause 20 or 21 , wherein the sluice comprises a closing member and a biassing means configured to bias the closing member towards the closed configuration.

Clause 23 The aquaculture system according to clause 22, wherein the biassing means is configured such that a differential hydrostatic pressure across the closing member can move the closing member from the closed position to the open position against the bias of the biassing member, thereby allowing water to flow through the sluice.

Clause 24 A method of raising aquatic organisms, comprising the steps of: providing an aquaculture system according to any of clause 1 to 23; floating the aquaculture system in a body of water; providing aquatic organisms and water in the containment region; and operating the first pump to pump water from the body of water outside of the aquaculture system to the containment region to maintain sufficient oxygen and/or a low carbon dioxide level in the containment region for the aquatic organisms to survive.

Clause 25 A method of raising aquatic organisms, comprising the steps of: providing an aquaculture system according to any of clause 16 to 19; floating the aquaculture system in a body of water; providing aquatic organisms and water in the containment region; and operating the first pump to pump water from the body of water outside of the aquaculture system to the containment region to maintain sufficient oxygen and/or a low carbon dioxide level in the containment region for the aquatic organisms to survive; and operating the second pump to pump water from the containment region to outside of the aquaculture system to dispose of used water.

Clause 26 A method of raising aquatic organisms, comprising the steps of: Providing an aquaculture system according to clause 23; floating the aquaculture system in a body of water; providing aquatic organisms and water in the containment region; and operating the first pump to pump water from the body of water outside of the aquaculture system to the containment region to maintain sufficient oxygen and/or a low carbon dioxide level in the containment region for the aquatic organisms to survive and to provide a hydrostatic pressure differential across the sluice thereby moving the sluice to the open configuration such that used water drains from the containment region through the sluice.

Claims

1 . An aquaculture system for raising aquatic organisms, comprising: a first rigid rearing unit (111) comprising a substantially watertight wall (112) and a substantially watertight base (112’), the substantially watertight wall (112) and substantially watertight base (112’) forming a containment region for containing water and aquatic organisms within in use; a first rigid buoyancy cell (141) configured to provide buoyancy to the aquaculture system; and a water processing room (170) comprising a first pump configured to pump water from outside of the aquaculture system to the containment region; wherein the first rigid rearing unit (111), first rigid buoyancy cell (141) and water processing room (170) are constructed in a monohull construction.

2. The aquaculture system according to claim 1 , wherein the first rigid rearing unit (111), first rigid buoyancy cell (141) and water processing room (170) are constructed of concrete or reinforced concrete or steel.

3. The aquaculture system according to claim 1 or 2, further comprising second and third rigid rearing units (121 , 131) and second and third rigid buoyancy cells (151 , 161), wherein the second and third rigid rearing units (121 , 131) and second and third rigid buoyancy cells (151 , 161) are part of the monohull.

4. The aquaculture system according to claim 3, wherein the second and third rigid rearing units (121 , 131) and second and third rigid buoyancy cells (151 , 161) are formed of concrete or reinforced concrete or steel.

5. The aquaculture system according to any preceding claim, wherein the aquaculture system is configured to float in a body of water creating a water line on the external surface of the aquaculture system in use, wherein the first pump is configured to be located at a position below the water line in use.

6. The aquaculture system according to any preceding claim, wherein the water processing room (170) is arranged to be directly above the water in which the aquaculture system floats in in use.

7. The aquaculture system according to claim 6, wherein the first pump is located within a first riser (19T), the first riser (19T) extending from the water processing room (170) substantially vertically downwards, such that in use the first pump can pump water from below the water processing room (170) through the first riser (19T) and into the containment region.

8. The aquaculture system according to claim 7, further comprising a second riser (191”) in the water processing room (170), the second riser (191”) being configured to deliver water from below the water processing room (170) into the containment region, wherein the first and second risers (19T, 191”) are arranged to deliver water to the containment region at different vertical locations in the containment region.

9. The aquaculture system according to any preceding claim, wherein the first pump is arranged to pump water through a first water treatment device (191’A) before the water enters the containment region.

10. The aquaculture system according to claim 9, wherein the first water treatment device (191’A) comprises one or more of: UV-radiation system; a filter; a water cleaning system; a water purification system.

11. The aquaculture system according to any preceding claim, wherein the first rigid buoyancy cell (141) is configured to receive ballast water in use, such that the buoyancy provided by the first rigid buoyancy cell (141) to the aquaculture system can be selectively reduced.

12. The aquaculture system according to any preceding claim, wherein the first rigid buoyancy cell (141) comprises an upper portion and a lower portion, wherein the upper portion comprises a buoyancy cell treatment room (141 A) and the lower portion comprises a buoyancy means.

13. The aquaculture system according to claim 12, wherein the buoyancy means is air.

14. The aquaculture system according to claim 12 or 13, wherein the buoyancy cell treatment room (141A) comprises a second pump (303) fluidly connected to the containment region and configured to pump fluid from the containment region to outside of the aquaculture system.

15. The aquaculture system according to claim 14, wherein the aquaculture system is configured to float in a body of water creating a water line on the external surface of the aquaculture system in use, wherein the second pump (303) is configured to be located at a position below the water line in use.

16. The aquaculture system according to claim 14 or 15, wherein the second pump (303) is arranged to pump water through a wastewater treatment unit (302) before the water is delivered to outside of the aquaculture system.

17. The aquaculture system according to claim 16, wherein the wastewater treatment unit (302) comprises one or more of: UV-radiation system; a filter; a water cleaning system; a water purification system.

18. The aquaculture system according to any preceding claim, wherein the first rigid rearing unit (111) comprises a sluice (200) configured to be moveable between a closed configuration and an open configuration, wherein in the closed configuration the sluice does not allow fluid communication between the containment region and the body of water within which the aquaculture system floats, and in the open configuration the sluice allows fluid communication between the containment region and the body of water within which the aquaculture system floats such that water within the containment region can be drained through the sluice (200).

19. The aquaculture system according to claim 18, wherein the sluice (200) comprises a grating cover (210) configured such that when the sluice (200) is in the open configuration such that water can flow through the sluice (200), aquatic organisms within the containment region cannot pass through the sluice (200).

20. The aquaculture system according to claim 18 or 19, wherein the sluice (200) comprises a closing member (220) and a biassing means (230) configured to bias the closing member (220) towards the closed configuration.

21. The aquaculture system according to claim 20, wherein the biassing means (230) is configured such that a differential hydrostatic pressure across the closing member (220) can move the closing member (220) from the closed position to the open position against the bias of the biassing member (230), thereby allowing water to flow through the sluice.

22. A method of raising aquatic organisms, comprising the steps of: providing an aquaculture system according to any of claims 1 to 21; floating the aquaculture system in a body of water; providing aquatic organisms and water in the containment region; and operating the first pump to pump water from the body of water outside of the aquaculture system to the containment region to maintain sufficient oxygen and/or a low carbon dioxide level in the containment region for the aquatic organisms to survive.

23. A method of raising aquatic organisms, comprising the steps of: providing an aquaculture system according to any of claims 14 to 17; floating the aquaculture system in a body of water; providing aquatic organisms and water in the containment region; and operating the first pump to pump water from the body of water outside of the aquaculture system to the containment region to maintain sufficient oxygen and/or a low carbon dioxide level in the containment region for the aquatic organisms to survive; and operating the second pump (303) to pump water from the containment region to outside of the aquaculture system to dispose of used water. A method of raising aquatic organisms, comprising the steps of: providing an aquaculture system according to claim 21 ; floating the aquaculture system in a body of water; providing aquatic organisms and water in the containment region; and operating the first pump to pump water from the body of water outside of the aquaculture system to the containment region to maintain sufficient oxygen and/or a low carbon dioxide level in the containment region for the aquatic organisms to survive and to provide a hydrostatic pressure differential across the sluice (200) thereby moving the sluice (200) to the open configuration such that used water drains from the containment region through the sluice (200).