NO20220268A1

NO20220268A1 - Fish farming system

Info

Publication number: NO20220268A1
Application number: NO20220268A
Authority: NO
Inventors: Inge-Bertin Almeland; Kristoffer Kjellså Jakobsen; Andreas Jo Falk Fredborg; Henrik Hannus; Svein Ersdal; Christian Kosacki
Original assignee: Aker Solutions As
Priority date: 2022-03-03
Filing date: 2022-03-03
Publication date: 2023-09-04

Description

FISH FARMING SYSTEM

FIELD

Some examples relate to a fish farming system and a method of operation thereof.

BACKGROUND

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

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

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

While positioning a fish farm in an open-water location provides more space, problems such as parasites (e.g. sea lice), and some diseases, still persist. This is particularly the case near the water surface, or in the upper part of the water column. Further, where the fish farm is located in a colder climate, ice can form on the net and other structural components of the fish farm that are positioned above the water. Floating ice may produce large loads on the net structure and the collar at the surface.

In response to these challenges, some attempts have been made to provide submersible fish farms that move both the fish and the structure, including the net, away from the parasites, diseases, ice and environmental loads found at or towards the surface. However, such attempts have been met with different problems, such as a lack of vertical stability of submerged structures, a lack of an air supply for swim bladder adjustment of physostomous fish, and straightforward and robust access to the fish enclosure for maintenance, replacement and monitoring of equipment and systems, while simultaneously permitting long-term submergence.

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

SUMMARY

It is an object of the present disclosure to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages in the prior art and solve at least the above mentioned problem. According to a first aspect there is provided a fish farming system, comprising a floatable structure comprising a collar and an access structure, a fish enclosure suspended from the floatable structure via a suspension arrangement, the collar defining an access opening therein for providing access to the fish enclosure, and the collar being configurable to be submerged, and the access structure connected to the collar, and being configurable to extend from a submerged location at which the access structure connects to the collar, to a location above a waterline.

According to some examples, the fish farming system may comprise a height adjustment means located on at least one of the access structure and the suspension arrangement.

The fish enclosure may comprise at least one of an upper structure and a lower structure. The fish enclosure may comprise both an upper structure and a lower structure.

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

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

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

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

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

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

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

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

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

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

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

The method may comprise connecting the fish farming system to a vessel. The method may comprise towing the fish farming system to a desired location in a body of water.

The method may comprise installing the fish farming system in a body of water via a crane on a vessel.

The method may comprise using the height adjustment means to lift the fish enclosure at least partially above a waterline.

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

CLAUSE 1. A fish farming system, comprising:

a floatable structure comprising a collar and an access structure;

a fish enclosure configurable to be suspended from the floatable structure via a suspension arrangement;

at least one of the collar and the access structure being configurable to have positive buoyancy in a body of water.

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

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

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

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

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

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

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

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

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

CLAUSE 11. The fish farming system according to any preceding clause, wherein the floatable structure comprises a plurality of collars, for example two collars, three collars or four collars.

CLAUSE 12. The fish farming system according to clause 11, wherein adjacent collars of the plurality of collars share at least one edge.

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

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

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

CLAUSE A1. A fish farming system, comprising:

a floatable structure;

a fish enclosure configurable to be suspended from the collar via a suspension arrangement;

height adjustment means for raising and lowering the enclosure relative to the floatable structure; and

the collar comprising a selectively deployable protector comprising a lice skirt extending around the periphery thereof, the selectively deployable protector being configurable between a retracted and a deployed configuration.

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

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

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

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

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

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

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

CLAUSE A9. The fish farming system of any of clauses A1 to A8, wherein the collar is configurable to be fully submerged in a body of water.

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

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

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

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

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

CLAUSE A15. A method of surfacing a fish enclosure of a submersible fish farming system, comprising:

suspending a fish enclosure in a first position from a floatable structure of a fish farming system in a body of water via a suspension arrangement;

configuring a selectively deployable protector located on the floatable structure to a retracted configuration when the fish enclosure is in the first position;

raising the fish enclosure to a second position, which is closer to the floatable structure than the first position;

configuring the selectively deployable protector to a deployed configuration when the fish enclosure is in the second position.

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

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

Further aspects described herein may be summarised by the following series of inventive B-clauses.

CLAUSE B1. A fish farming system, comprising:

a floatable structure;

an access tube comprising a conduit extending between the suspended fish enclosure and the floatable structure.

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

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

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

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

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

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

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

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

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

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

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

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

BRIEF DESCRIPTION

The above objects, as well as additional objects, features and advantages of the present disclosure, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of example embodiments of the present disclosure, when taken in conjunction with the accompanying drawings. Figure 1 illustrates a known example of a fish farm.

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

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

Figures 4a and 4b illustrate an elevation view of examples of an access structure. Figures 5a and 5b illustrate a plan view of access of a collar and access structures. Figures 6a and 6b illustrate examples of a fish farming system.

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

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

Figure 9 illustrates a further example of a fish enclosure in elevation and plan views. Figures 10 to 12 illustrate various examples of features of a fish farming system. Figures 13a and 13b illustrate further details of a fish farming system.

Figures 14a and 14b are further examples of a fish farming system comprising a floatable structure.

Figures 15a to 15c, 16 and 17a and 17b illustrate a fish farming system comprising a selectively deployable protector.

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

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

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

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

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

DETAILED DESCRIPTION

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

An aspect of the present disclosure relates to a fish farming system comprising a floatable structure comprising a collar and an access structure, a fish enclosure is suspended from the floatable structure via a suspension arrangement. According to some examples the collar may define an access opening centrally therein for providing access to the fish enclosure through the collar. The collar is configurable to be submerged in an exposed open-water location, such as an offshore location. The access structure is located on the collar, and is configurable to extend from a submerged location at a point of contact with the collar, to a location above the waterline, for example to permit raising and lowering of the fish enclosure relative to the collar.

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

Figure 1 illustrates a known example of a fish farm 1, as is disclosed in International application No. PCT/NO2021/050128. Here, the fish farm 1 comprises a fish enclosure with a floating collar 2 comprising a lower ring 7, and upper ring 9, connected by a plurality of columns 8. The fish farm 1 comprises a net cage 3 suspended from the floating collar 2. In use, the floating collar 2 may be located on the surface of a body of water, while the net cage 3 extends below the floating collar 2. The entire floating collar 2 may therefore be exposed to surface waves, which in open waters can be very large, and use of the fish farm 1 may be restricted to locations where the magnitude of waves is known to be limited.

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

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

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

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

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

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

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

The floatable structure 101 also comprises an access structure 102 located on, and extending from, the collar 102. The access structure 108 may extend vertically from the collar 102, in this example vertically upwardly. The access structure 108 extends above a waterline 110, while the collar 102 is fully submerged (i.e. substantially all the collar 102 is located below the waterline). The floatable structure 101 therefore comprises a submerged portion (the collar 102 and a lower section of the access structure 108) and a portion above the waterline (an upper section of the access structure 108) and therefore the floatable structure 101 can be considered to be a semi-submersible structure.

The access structure 108 may connect to the collar by any appropriate means, for example by bolting, welding, chemical bonding or the like. The access structure 108 may be integrally formed with the collar 102, in which case the connection between the access structure 108 and the collar 102 may be defined by a change in geometry of the annularly structured collar 102 and the geometry of the access structure 108, which may be a column or prism shape.

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

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

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

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

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

The floatable structure 101 may be buoyant (or comprise a degree of buoyancy) such that the collar 102 is configurable to be completely submerged, while the access structure 108 (or plurality thereof) is configurable to extend above a waterline from the collar 102. For example, the buoyancy of the access structure 108 or structures and the buoyancy of the collar 102 may be adapted or selected so as to provide the floatable structure 101 to permit the collar 102 to be completely submerged in a body of water, and for the access structure 108 or structures to extend above the waterline of the body of water. As previously described, at least one of the collar 102 and the access structure 108 or structures may be positively buoyant, one of the collar 102 and the access structure 108 may be positively buoyant and the other negatively buoyant, or the like, in order to provide the floatable structure 101 with the desired degree of buoyancy.

In the example of Figures 2a and 2b, the access structure 108 is in the form of a plurality of columns (e.g. pillars) extending upwardly from the collar 102. At least one, or each, of the plurality of columns may extend vertically upwardly from the collar 102, or may extend upwardly at an oblique angle to the collar 102 (e.g. relative to an upper surface, or to a circumferentially or peripherally extending axis through the centre of the collar structure). The plurality of columns of the access structure 108 may be equidistantly spaced around the collar, or may be located in a plurality of groupings of two or more columns (where the columns in each grouping are adjacently located).

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

In Figure 15c, the fish farming system 100 is illustrated as having an expanded lice skirt 142 along each side of the square frame of the collar 102. In the example of Figure 15c, the lice skirt 142 may be expanded simultaneously along each side of the frame of the collar 102 as a single lice skirt 142, or may be deployable individually as four separate lice skirts 142, one along each side of the collar 102.

The, or each, lice skirt 142 may be expanded during times where it is desirable to surface the fish enclosure e.g. bring fish in the fish enclosure 104 to the surface (e.g. waterline) of the body of water in which the fish farming system 100 is positioned, such as for harvesting or inspection of the some/all of the fish. In such cases, the fish enclosure may initially have a first, operational, position and the fish enclosure 104 may then be raised towards the waterline 110 to a second, maintenance or access, position to provide easier access to the fish therein. As the fish are brought to the surface of the water, they may become vulnerable to infestation from parasites located towards the water surface such as sea lice. By deploying the lice skirt 142 prior to raising the fish enclosure 104, sea lice and other parasites may be prevented from entering the space in the centre of the collar, where fish are accessible to be monitored, inspected and/or harvested.

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

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

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

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

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

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

During transportation and initial positioning of the fish farming system 100, the fish enclosure 104 may be in a collapsed configuration, in which the boundary material is held together (e.g. folded or rolled together) about a rigid frame 140 or rigid frames 140a, 140b (see Figures 14a and 14b), of the upper and/or lower structures 112, 114 of the fish enclosure 104. In the case where the fish farming system 100 comprises both an upper and a lower structure 112, 114, the structures may be held together by a tie 154 during transport. The tie 154 may enable the fish farming system 100 to be transported stably, and may then be undone, removed or severed once the fish farming system 100 is positioned in an offshore location, and it is to be installed.

Although not shown in Figure 18, a suspension arrangement connects the fish enclosure 104 to the collar 102.

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

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

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

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

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

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

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

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

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

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

Alternatively or additionally, the support arrangement 152 may be used to provide access to the fish enclosure for the purpose of providing a net replacement.

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

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

An additional measure that may be taken to increase the stability of the air pocket structure 132 is the attachment or integration of weights to a lower part thereof.

Figure 18b illustrates weights 162 attached to the lower periphery of the air pocket structure 132. Similar to the buoyancy element(s) 156, the weights may assist to prevent the air pocket structure 132 from tipping or flipping.

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

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

In Figures 22a and 22b, the collars 102, 102a, 102b comprise an access structure 108 at each vertex thereof. In the example of Figure 22c, some vertices of the collar 102 are absent an access structure 108, while an access structure 108 is present at a midpoint of an edge (e.g. a side) of the collar 102.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

The person skilled in the art realizes that the present disclosure is not limited to the preferred embodiments described above. The person skilled in the art further realizes that modifications and variations are possible within the scope of the appended claims. Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed disclosure, from a study of the drawings, the disclosure, and the appended claims.

Claims

1. A fish farming system, comprising

a floatable structure comprising a collar and an access structure;

a fish enclosure suspended from the floatable structure via a suspension arrangement,

the collar defining an access opening therein for providing access to the fish enclosure, and the collar being configurable to be submerged, and

the access structure connected to the collar, and being configurable to extend from a submerged location at which the access structure connects to the collar, to a location above a waterline.

2. The fish farming system of claim 1, comprising a height adjustment means located on at least one of the access structure and the suspension arrangement.

3. The fish farming system of claim 1 or 2, wherein the fish enclosure comprises at least one of an upper structure and a lower structure.

4. The fish farming system of claim 1 or 2, wherein the fish enclosure comprises both an upper structure and a lower structure.

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

6. The fish farming system of claims 4 and 5, wherein the air pocket is housed in the upper structure and the weighted frame is defined by the lower structure.

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

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

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

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

11. The fish farming system of claim 10, wherein the suspension arrangement comprises a flexible elongate member that extends between the floatable structure and the fish enclosure.

12. The fish farming system of any preceding claim, wherein the access structure comprises a height adjustment means for raising and lowering the fish enclosure relative to the floatable structure and the height adjustment means comprises an elongate member extending from the access structure to the fish enclosure.

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

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

15. The fish farming system of any preceding claim, comprising a hang-off arrangement located at the base of the collar, the suspension arrangement being coupled to the hang-off arrangement.

16. The fish farming system of claim 15, wherein the hang-off arrangement comprises a restrictor comprising a seat for a plug located on the suspension arrangement, wherein when the plug is seated in the restrictor, and movement of the suspension arrangement relative to the collar is restricted.

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

18. The fish farming system of claim 17, wherein the collar has a rectangular horizontal cross-section, and comprises an access structure at each corner thereof.

19. The fish farming system of any preceding claim, comprising a plurality of access structures, each of the plurality of access structures being located radially inwardly of the collar.

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

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

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

23. The fish farming system of claim 22, wherein the lice skirt is at least partially supported by the access structure, and is configurable to extend above a waterline.

24. A method for operation of a fish farming system, comprising:

providing a floatable structure, comprising a collar and an access structure located on the collar, in a body of water;

submerging the collar below a waterline in the body of water such that the access structure extends between a submerged point of contact with the collar and a location above the waterline of the body of water;

suspending a fish enclosure from the floatable structure via a suspension arrangement;

providing access to the fish enclosure through the collar via a central recess defined in the collar.

25. The method of claim 24, comprising connecting the fish farming system to a vessel, and towing the fish farming system to a desired location in a body of water.

26. The method of claim 24 or 25, comprising installing the fish farming system in a body of water via a crane on a vessel.

27. The method of any of claims 24 to 26, comprising using the height adjustment means to lift the fish enclosure at least partially above a waterline.