NO346673B1

NO346673B1 - A fish farm and method for managing fish in a fish farm

Info

Publication number: NO346673B1
Application number: NO20210040A
Authority: NO
Inventors: Per Kristian Bruun; Kristoffer Kjellså Jakobsen; Andreas Jo Falk Fredborg; Pål Lindstad
Original assignee: Aker Solutions As
Priority date: 2021-01-12
Filing date: 2021-01-12
Publication date: 2022-11-21
Also published as: NO20210040A1

Description

A FISH FARM AND METHOD FOR MANAGING FISH IN A FISH FARM

The present disclosure relates to a fish farm and a method for managing fish in a fish farm.

BACKGROUND

The use of fish farms to rear fish is widely known, and such farms are often used to rear large numbers of fish within an enclosure, thereby reducing strain and reliance on wild fish populations to satisfy consumer demand for fish products. Fish farms may be arranged offshore, such as in the sea or ocean, or in some cases a fish farm may be positioned in a river or in another body of water, e.g. in a natural lake, or in an artificially created body of water.

Documents useful for understanding the field of technology include GB 2571926 A, which shows a method and apparatus for temporarily reducing the volume of water within which fish may swim within a fish farm enclosure; EP 3671565 A1, which shows a device, system and method for fish counting; NO 890628 L, which shows a method and arrangement for sorting fish; and WO 2018117856 A1, which shows a device and method for removing lice of fish.

SUMMARY

A first aspect of the invention relates to a fish farm comprising: a first enclosure, a second enclosure; the first enclosure being connected to the second enclosure by an access arrangement for selectively permitting movement of a fish between the first enclosure and the second enclosure; the first enclosure and the access arrangement being positioned within the fish farm such that both the first enclosure and the access arrangement are fully submergible when positioned in a body of water.

According to a second example, the fish farm may comprise a restrictor arrangement in cooperation with the access arrangement for selectively permitting access between the first and second enclosures.

According to a third example, the restrictor arrangement may be located in the access arrangement.

According to a fourth example, the restrictor arrangement may selectively prevent movement of fish between the first enclosure and the second enclosure. Having such a restrictor arrangement may permit a user to control movement between the enclosures of the fish farm, by permitting or restricting access of a fish between the enclosures.

According to a fifth example, the restrictor arrangement may comprise a plurality of rigid bars with spaces therebetween for permitting a fish to pass therethrough.

According to a sixth example, the restrictor arrangement may comprise a first and a second set of rigid bars , each set having spaces therebetween for permitting a fish to pass therethrough, the first set of rigid bars being slidably may be moveable relative to the second set of rigid bars between an open position (as shown in Fig.5b), in which the spaces between the rigid bars of the first and second set of rigid bars are aligned, and a closed position (as shown in Fig.5a), in which the rigid bars of the first set of rigid bars are aligned with the spaces of the second set of rigid bars, thereby restricting passage of a fish therethrough.

According to a seventh example, the first set of rigid bars may be positioned relative to the second set of rigid bars such that the bars of the first set of rigid bars partially overlap with the spaces of the second set of rigid bars, thereby reducing the space available for passage of a fish therethrough.

According to an eighth example, each of the bars in the first set of rigid bars may be parallel to each other, and each of the bars in the second set of rigid bars may be parallel to each other, and the first set of rigid bars may be arranged such that the bars are parallel to the second set of rigid bars.

According to a ninth example, at least one of the first and second sets of rigid bars may be remotely moveable by a user. Having a plurality of rigid bars, which may comprise a moveable first and second set, may permit a user to provide a variable degree of restriction in the restrictor arrangement, thereby permitting the restrictor arrangement to only restrict the passage of fish therethrough above a certain size, which may be able to be determined by said user.

According to a tenth example, the fish farm may comprise a sensor arrangement comprising a counter for counting the number of fish passing through the access arrangement.

According to an eleventh example, the fish farm may comprise a sensor arrangement comprising a sensor for measuring the size and biomass of each fish passing through the access arrangement.

According to a twelfth example, fish farm may comprise a restrictor arrangement and the sensor arrangement may provide data to a user or a control system for enabling selective access between the first and second enclosures. Having a sensor arrangement located so as to permit sensing such as counting or size/biomass analysis of each fish passing through the access arrangement may provide the user with a convenient and accurate method for measurement. Coupling the sensor arrangement with the access arrangement may ensure that all, or a significant portion, of the fish passing through are sensed by the sensor arrangement. In contrast, other systems may attempt to measure the number and biomass of fish in a fish farm by scanning the fish in an enclosure, which technique may not be able to individually analyse each fish, and may require estimations or guesswork, thereby decreasing the level of accuracy of such systems.

Where the sensor arrangement is connected to a control system for operating the access port and/or a lure arrangement(s), this may enable a user to turn the sensor arrangement on when necessary, receive information from the sensor arrangement such as information relating to the biomass of the sensed fish, information relating to the status of the restrictor arrangement, or the like. In addition, it may enable a user to control the restrictor arrangement based upon the information provided by the sensor arrangement, such as closing the restrictor arrangement once a desired weight/biomass of fish has passed through the restrictor arrangement, estimating the biomass of fish that have passed through the restrictor arrangement (e.g. by estimating the average biomass of each fish), providing a statistical representation of the differing weights of fish that have passed through the restriction arrangement and optionally adjusting the lure arrangement and/or to monitor the health condition of the fish passing through the restrictor arrangement etc..

According to a thirteenth example, the access arrangement may comprise a first and a second access port located in each of the first and second enclosures and the sensor arrangement is located adjacent at least one of the first and second access ports.

According to a fourteenth example, the access arrangement may comprise a shaft extending between the first and the second enclosure.

According to a fifteenth example, the access arrangement comprises an aperture, and the first enclosure comprises an entry port directly connected to an entry port of the second enclosure.

According to a sixteenth example, the access arrangement may comprise a conduit extending between the first and the second enclosure. The access arrangement, and optionally the conduit may provide access in one direction, for example by comprising a one-way opening such as a unidirectional flapper, or a flapper that is able to be configured between unidirectional (the direction of which may be selectable by a user) and a bidirectional configuration if required. The configuration of the one-way opening may be controlled remotely by a user, e.g. wirelessly, who may be able to decide in which direction(s) access through the flapper is permitted. In some examples, the access arrangement may be or define a flexible sleeve. The flexible sleeve may be held open at one end, thereby permitting a fish to swim easily through the flexible sleeve from the end that is held open, but making passage in the opposite direction more difficult. As such, the flexible sleeve may function as a one-way opening.

Having an access arrangement comprising an aperture, and optionally a conduit may permit the access arrangement to connect enclosures in various configurations of fish farm, and may enable the structure of a fish farm to be reconfigured (e.g. enclosures within the fish farm moved) while still permitting functioning of the access arrangement.

According to a seventeenth example, the fish farm may comprise a third enclosure, and the access arrangement may be configured to selectively permit movement of a fish between the third enclosure and at least one of the first and second enclosures.

According to a eighteenth example, the access arrangement may permit movement of a fish between the first and third enclosure via the second enclosure.

According to an nineteenth example, the second enclosure may be located above the first enclosure.

According to a twentieth example, the second enclosure may be smaller than the first enclosure. The second enclosure may therefore be conveniently replaced for removal from a fish farm. Additionally, having the second enclosure be smaller than the first enclosure may limit the number of fish therein, making removal of the second enclosure easier, and ensuring a vessel for removing fish from a fish farm is not overwhelmed by the number of fish in the second enclosure.

According to a twenty-first example, the first and second enclosures may comprise or may be connected to a ballasting system to permit the draft (i.e. the height of the first and second enclosures relative to the surface of the surrounding fluid) of the first and second enclosures to be varied.

According to a twenty-second example, both the first and the second enclosures may be completely submerged in a subsea location. As such, the location of the enclosures may protect the fish therein, for example from waves, sea lice and from surface predators.

According to a twenty-second example, the fish farm may comprise an extraction conduit at least partially located in at least one of the enclosures for removal of a fish therefrom.

According to a twenty-third example, the fish farm may comprise a surveillance system for monitoring movement of a fish in at least one of the enclosures of the fish farm. The surveillance system may assist a user to know where in the fish tank the fish are mainly located, which may be useful in times where the fish are required to be removed from the fish farm.

According to a twenty-fourth example, the fish farm may comprise a lure arrangement for motivating movement of a fish from the first enclosure to the second enclosure.

According to a twenty-fourth example, the lure arrangement may comprise at least one of: a supply of fish feed, an air pocket, a light source, a source of sound (e.g. a speaker or sound transmitter), a source of an attractive or a repulsive smell and a fluid propeller. The lure arrangement may be attractive to a fish, may be repulsive to a fish, or may comprise some degree of attraction and some degree of repulsion to a fish (for example so as to repel fish from one enclosure while simultaneously attract said fish to a second enclosure).

According to a twenty-fifth example, the lure arrangement may be located in each enclosure of the fish farm.

According to a twenty-sixth example, the lure arrangement may be able to be selectively activated within an enclosure of the fish farm. As such, the lure arrangement may be activated to lure fish to a desired enclosure.

According to a twenty-seventh example, at least one of the first and second enclosures may comprise a volume restriction device for reducing the volume of space available to a fish therein.

According to a twenty-eighth example, the volume restriction device may be in the form of a sliding bulkhead.

According to a twenty-ninth example, the sliding bulkhead may comprise a net material. According to a thirtieth example the sliding bulkhead and at least one enclosure may each comprise a profile, the profile of each configurable to engage so as to control the position of the bulkhead.

In other examples, volume restriction may be achieved by de-ballasting the fish farm to raise the height of the fish farm above the water surface, such that at least a portion of at least the first and/or second enclosure is located above the water surface, thereby using the water surface as a form of volume restriction device. Use of a sliding bulkhead in the first and/or second enclosures may be in addition to de-ballasting the fish farm to form a volume restriction device.

According to a thirty-first example, both the first and second enclosures may be contained within an outer enclosure.

According to a second aspect of the invention, there is provided a method for managing fish in a fish farm, comprising: providing a first enclosure and a second enclosure, the first enclosure being connected to the second enclosure by an access arrangement for selectively permitting movement of a fish between the first enclosure and the second enclosure; housing a fish in the first enclosure; permitting a fish in the first enclosure access to the second enclosure by positioning the first enclosure and the access arrangement such that both are fully submerged when positioned in a body of water.

According to a second example of the second aspect, the method may comprise using the lure arrangement to motivate a fish to move from the first enclosure to the second enclosure, or from the second enclosure to a third enclosure. The lure arrangement may be attractive to a fish, repulsive to a fish, or have a combination of both attractive features and repulsive features. As such, the lure arrangement may be used to repel a fish from the first enclosure and into the second enclosure, while at the same time being used to attract a fish from the first enclosure to the second enclosure, thereby increasing the efficacy of the lure arrangement.

According to a third example of the second aspect, the method may comprise extracting a fish from the second enclosure.

According to a fourth example of the second aspect, the method may comprise closing the access from the first enclosure to the second enclosure and detaching the second enclosure from the fish farm.

According to a fifth example of the second aspect, the method may comprise housing a plurality of fish in the first enclosure, and housing a plurality of fish in the second enclosure, and feeding the plurality of fish in the first enclosure regularly, while starving the fish in the second enclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics will become clear from the following description of illustrative embodiments, given as non-restrictive examples, with reference to the attached drawings, in which:

Figure 1 illustrates a simplified sectional perspective view of a fish farm.

Figures 2-4 illustrate a side view of a fish farm and operation thereof.

Figures 5a-c illustrate an access unit of the fish farm.

Figure 6 illustrates a top view of the enclosures and access units of a fish farm.

Figure 7 illustrates a side view and operation of another example of a fish farm.

Figures 8-14 show an example of a volume restriction device.

Figures 15-21 show various examples of a fish farm and operation thereof.

Figures 22-24 illustrates a further example of a fish farm.

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.

During the course of fish farming operations, there is often the need to move a number of fish from one location to another. For example, when part of the fish farm need to be cleaned or replace. Additionally, when harvesting fish in a fish farm, the fish must be extracted from their enclosure.

Commonly, nets are used to form the enclosure and the space for the fish in the nets may be reduced, e.g. by squeezing the net structure to force the fish out of their enclosure and into a vessel, for example, where the fish may be taken to a processing centre or to another fish farm, or by forcing the fish out of a first enclosure and into a second enclosure to enable cleaning or repair of the first enclosure. While this approach provides one method of extracting fish from their enclosure, it may harm some or all of the fish as a force may be applied to the fish when reducing the space of the enclosure due to crowding with other fish, in some cases resulting in crush and/or stress induced injuries to, and potentially mortality of, the fish. In cases where the extraction or displacement of only a small number of fish is required, e.g. for sampling of live fish of for harvesting fish that have grown to a large size, this method may result in stress or injury to all fish in the fish farm, as it may not be possible to selectively extract fish from the fish farm or move fish within the fish farm. Therefore the risk of harm and/or injury to all fish in the farm is introduced. This has a negative effect not only on the fish that are desired to be harvested or moved, but also other fish that do not require to be moved or extracted, for example because they may not yet have fully matured, and/or that may be still be small in size. Ideally, such fish are intended to stay in the enclosure, where they may be allowed to grow and mature until a later time when their harvesting may be more economically viable. In some cases, it may be necessary to move a portion of the fish in the fish farm, for example because the capacity of the fish farm (or an enclosure thereof) has been reached. In this case, avoiding any stress to the remaining fish is highly desirable.

Prior to handling operations, transportation and treatment it is common practice in the fish farming industry to starve the fish, as this makes the fish more capable of handling the stress from such operation. The starving period typically lasts a few days depending on factors such as temperature, species and size of fish. Starvation can have a negative impact on fish welfare and also represents a considerable loss for the farmer in the form of lost growth. With current methods, all the fish inside a fish cage must be starved in preparation for an extraction of just a portion of the fish. It is hence an objective to limit starvation to only the fish that will be handled.

This disclosure aims at providing an apparatus and a method to move fish from or within a fish farm without harming them, as well as enabling the selection a desired amount and/or type of fish prior to extraction and facilitate starving of only the selected fish.

Figure 1 shows simplified diagram of a fish farm 100 according to the present disclosure comprising a first enclosure 130. The fish farm 100 is located in a body of water, which may be the sea or ocean. The fish farm 100 comprises a floating structure 104 having a positive buoyancy. The floating structure 104 comprises a lower pontoon collar 102 which may assist to provide buoyancy to the floating structure 104. The lower pontoon collar 102 may be hollow, or comprise a hollow portion thereof, and/or may comprise or be constructed from a buoyant material such as a buoyant foam or plastic, and/or may comprise buoyant members connected thereto, such as buoys or foam flotation members. The lower pontoon collar may additionally comprise means to selectively alter the draft thereof (as well as the draft of the floating structure 104 of the fish farm), e.g. a fluid inlet and a pump for pumping water into and out of the lower pontoon collar 102 in a ballast arrangement to alter the height of the lower pontoon collar above the water level. The floating structure 104 may additionally comprise an upper collar 103 which may assist to provide additional stability to the fish farm 100 when located in an offshore location. The upper collar 103 may have an open top section to permit easy access to the fish farm 100, or may comprise a cover, net, mesh or the like having a hatch or opening therein through which the fish farm 100 may be accessed. In addition, the upper collar 103 may comprise an access structure (not illustrated in Figure 1) to facilitate access to the fish farm 100 by a user. The access structure may be in the form of a metal frame and/or platform on which a user may be able to stand, balance against, position equipment, secure a floating vessel thereto etc.. The lower pontoon collar 102 and the upper pontoon collar 103 are connected by an arrangement comprising columns and/or trusses 101 in this example. In some examples, the fish farm 100 may comprise an additional or alternative arrangement to provide stability and buoyancy to the first enclosure 130, e.g. a system of tensioned ropes or a frame surrounding the first enclosure 130.

Below the floating structure 104 a first net 105 is arranged. In this example the first net 105 has a cylindrical shape, one end of which is conically shaped. In another example, the first net 105 may have a different shape, e.g. may be cuboid, conical, frusto-conical, or in the form of some other extruded polygonal. In some examples the first net 105 may comprise no bottom part 105a or may comprise a bottom part 105a of another shape, for example a pyramidal shape, a dome shape or the net may be flat-bottomed, in this case meaning that the bottom part would comprise a circular shape. The first net may comprise or be connected to a top net 106. The top net 106 may form one end of the cylindrical shape of the first net 105, such that the top net 106 has a circular form. In some examples, the first net 105 may not be in the form of a cylinder, but another shape (e.g. another extruded shape) and the top net 106 may be shaped correspondingly so as to form an enclosure in combination with the first net 105. The shape of the top net 106 may correspond to the shape of an opening in the first net, such that the top net 106 is able to close the opening, if necessary. For example, where the first net 105 has the shape of an extruded pentagon, then the top net 106 may be pentagonal in shape. The top net 106 may lie above the water surface, or below the water surface depending on the draft of the fish farm 100. The first net 105 and the top net 106 may together form a first enclosure 130 for the fish. Located above the top net 106 in this example is a cover 112, which in this example is a net or membrane that may be permeable to water. The cover may assist to provide protection to the fish farm, for example from predators such as seabirds and may additionally assist to prevent fish from leaping from the fish farm 100. A further enclosure may therefore be formed between the top net 106, the cover 112 and a peripheral net 114. In some examples, it may be possible to insert a vertically extending net (not shown) between the cover 112 and the top net 106, which may be used to divide the enclosure between the top net 106 and the cover 112 into further enclosures.

As illustrated, surrounding the first net 105 is a second net 111. The second net 111 may be arranged as a double barrier to protect against damage to the enclosure 130 (e.g. to protect against damage to the first net 105 of the enclosure) and additionally to protect the fish contained in the enclosure 130 e.g. by keeping predators away or by reducing impact forces of objects hitting the fish cage. The second net 111 may additionally assist to improve the security of the fish farm 100 by assisting to prevent escape of fish from the enclosure 130, should there be a breach in the first net 105. Provided sufficient spacing between the nets, two independent incidents involving damage to both nets would be required in order for fish to escape, thereby drastically reducing the chances of fish escape.

The first net 105 and second net 111 may be secured together by a securing arrangement. For example by using a series of connectors 113 such as rope or ties that may be held in tension between the nets, thereby restricting the movement of the first net 105 relative to the second net 111 which may improve the stability of the fish farm 100 by preventing erratic movement of the first net 105 inside the second net 111. The securing arrangement may be located on the first net 105 at the interface between the first net 105 and the bottom part of the first net 105a, while the securing arrangement may be located on the second net 111 at the interface between the second net 111 and a bottom part of the second net 111a. The securing arrangement may, in some examples, connect the first net 105 and the second net 111 together at the interface between each net 105, 111 and the respective bottom part 105a, 111a thereof. The securing arrangement may comprise a frame structure or two frame structures, and the frame structure or structures may be connected to one or both of the first and/or second nets 105, 111. The frame structure may be the same shape as the net to which it is attached, e.g. the same shape as the cross-section of the net 105, 111 to which it is attached. In this example, the frame structure may be circular in shape as the first and second nets 105, 111 are cylindrical in shape.

In some examples, there may be a weighting element attached to the first and second net 105,111, e.g. a metal collar, a collar filled with a weighted material such as cement or any other material with a density greater than that of the surrounding water of the fish farm 100, a plurality of weighted capsules or other components, etc.. The weighting element may assist to provide tension in the first and second net 105,111 in a direction in which the first and second nets 105, 111 extend (e.g. in a vertical direction) and reduce deformation or movement of the enclosure 130 (e.g. of the nets 105, 111 in the enclosure) due to external forces such as those caused by wave motion and sea/ocean currents. As such, having a weighted element may assist to improve the stability of the enclosure 130 of the fish farm by reducing the movement thereof.

The weighted element may be positioned on or connected to either or both of the first and second nets 105, 111, and may be located at or towards the lower end of the first and second nets 105, 111 at the connection between the first and second nets 105, 111 and the pontoon structure 104 (e.g. the lower pontoon collar 102). The weighted element may be positioned around the periphery of the first and/or second nets 105, 111, and may be positioned in a single plane (e.g. may be positioned at a constant vertical location). The weighted element may, in some examples, comprise a plurality of weighted components, positioned at a plurality of locations on the fish farm 100. The weighted element may be flexible or may be a rigid continuous structure. In the case of a rigid weighted element, the weighted element may additionally assist to prevent deformation of the nets. The weighted element, or an additional weighted element, may be provided at the interface between the first and/or second net 105, 111, and the respective bottom part of one or each of the first and second nets 105, 111, thereby assisting to hold the first and/or second nets 105, 111 in tension in the water.

At least a part of the conical section of the first enclosure 130 may be or comprise a reinforced material – in this example, the vertex of the conical section of the first enclosure 130 comprises a reinforced material. Here, the vertex of the conical section of the first enclosure 130 is located at the lowermost point of the first enclosure 130. The vertex of the conical section of the first enclosure 130 may comprise a mort collection system 131 for removing mort, i.e. dead fish and optionally other detritus, from the first enclosure 130 which may naturally sink to the vertex of the bottom part 105a, being the lowest point in the first enclosure 130. The mort collection system 131 may be connected to a fish transport means 2002 which will move the collected mort to a mort processing unit, e.g. by using a flow of water to transport the collected mort. The second net 111 has a similar shape relative to the first net 105 comprising a cylindrical shape with a conically shaped end. In another example, the second net 111 may have a different shape, e.g. cuboid or may have a shape differing from the first net 105. The bottom of the conical section of the second net 111 may also be reinforced as shown in Figure 1.

In this example, the fish farm 100 is fixed to its offshore location by an anchoring system comprising multiple lines 120a-e such as wires, chains, ropes, or the like, which may be anchored to the seabed or some other static location such as shore, a moored frame or subsea infrastructure.

Figures 2-4 show a side view of a fish farm 200 which is substantially similar to that as previously described. As such, similar reference numerals will be used to describe similar components, augmented by 100.

The fish farm 200 is illustrated comprising a first enclosure 230 and a second enclosure 240, Figures 2-4 representing a method of operating the fish farm 200 according to the present disclosure. Here, the first enclosure 230 and the second enclosure 240 are connected by an access unit 251 which is comprised in an access arrangement 250. In this example, the fish farm 200 comprises a third enclosure 232. Here, the first enclosure 230 may be substantially similar to the third enclosure 232, in that both are the same or a similar shape, and both are connected to a floating structure of the fish farm 200. The third enclosure 232 is connected to the second enclosure 240 by second access unit 252 belonging to the access arrangement 250, such that in this example the fish farm 200 may comprise several access units. For example, the number of access units may correspond to the number of enclosures present. The number of access units may be one fewer than the number of enclosures present, or more than this in the case where there is more than one access unit present between any two enclosures. Both the first and the third enclosures 230, 232 are completely submerged below the surface of the water 290, as is the access arrangement 250. The second enclosure 240 is located closer to the water surface 290 in this example, and may not be completely submerged in the water. As such, at least a part of the second enclosure 240 may be located above the water surface 290, which may be useful in times when it is required to crowd fish in the second enclosure 240, as will be described in more detail in the following paragraphs.

In this Figure, the second enclosure is located above the first enclosure 230 (and the third enclosure 232), and is located in the floating structure 204 of the fish farm. It should be noted, however, that the second enclosure 240 is not required to be located above the first and optionally the third enclosure in all examples. The second enclosure 240 may be positioned on the same level as (e.g. to the side of) the first and/or third enclosure 230, 232, or any other enclosure that may be equivalent to the first/third enclosure. The second enclosure 240 is secured to the floating structure 204, in this example by ropes or ties 258, and here occupies a volume that is smaller than the floating structure 204. The second enclosure 240 may be made from a flexible net structure that is supported by ropes or ties 258, or may be made from a collection of rigid net panels to form a rigid frame structure, with netting located in the frame openings. In some examples, the second enclosure 240 may be made from rigid panels (e.g. of steel or plastic) which may be water permeable, or in some examples the rigid panels may not be water permeable, in which case a water circulation system may be provided, for example through use of a fluid pump arrangement. The size of the second enclosure 240 relative to the floating structure 204 may permit the second enclosure 240 may be held below the water surface. To illustrate this point by way of example, where the floating structure 204 is 20 metres in height, the second enclosure may be 10 metres in height, such that it extends half-way up the height of the floating structure 204, and is located at least 10 metres below the water surface, which may be recognised as being sufficient to assist to protect fish inside the second enclosure 240 from surface predators, waves, sea lice etc.. In some examples, the second enclosure 240 may be able to be moved within the floating structure 204. The second enclosure 240 may be able to be moved closer to the water surface, which may be useful for removing the second enclosure 240, for example for cleaning purposes, or when the fish inside the second enclosure 240 are desired to be removed from the fish farm 200.

Here, the access arrangement 250 enables selective access between the first enclosure 230, the second enclosure 240 and the third enclosure 232. Access between the first enclosure 230 and the third enclosure 232 may be via the second enclosure 240, as is the case in this example. Here, the access arrangement 250 is horizontally oriented, as the second enclosure 240 is located above the first/third enclosure 230, 232. However, in examples where the second enclosure 240 is located to the side of the first/third enclosure 230, 232, then the access arrangement 250 may be vertically oriented.

The access arrangement 250 and the selective access between the enclosures 230, 240, 232 will be described in detail referring to Figures 5a-c. In another example, there may be two enclosures, e.g. the first and second enclosure 230,240 and the access arrangement 250 may enable access between these two, comprising only one single access unit 251. In yet another example, the first and third enclosure 230,232 may be present and the access arrangement 250 may enable direct access between these two, the fish farm 200 thereby comprising only one access unit 251 leading directly from the first to the third enclosure 230, 232. The access arrangement 250 comprises entry ports at the enclosures 230,232,240 to connect one enclosure to another enclosure 230,232,240 as will be shown in detail in Figures 5a-c. In addition to an entry port or entry ports, the access arrangement 250 may comprise a shaft (e.g. a hollow shaft) extending between the entry ports to connect the enclosures 230,232,240 to permit passage between the entry ports, and thereby the enclosures 230,232,240. In other examples the access arrangement 250 may comprise a tubular or conduit that connects the entry ports, thereby assisting to bridge any gap that may be present between at least two of the enclosures 230,232,240, while still permitting passage of a fish therebetween. In such examples, a shaft, tubular or conduit may enable the passage of fish between two enclosures that are not directly adjacent. In another example, the access arrangement 250 may be configured such that the entry ports of the different enclosures 230,232,240 are directly connected to one another, for example in cases where at least two of the enclosures 230,232,240 are sufficiently close that no connecting shaft, tubing or conduit is necessary.

The fish farm 200 of the described example comprises a lure arrangement, the lure arrangement comprising lure units 245a-c being arranged in the first, second and third enclosure 230,232,240 respectively for the purpose of luring a fish to the lure unit 245a-c in each of the enclosures 230,232,240. In some examples, there may be multiple lure units 245a-c in each, any or all of the enclosures 230,232,240 or there may be lure units 245a-c only in selected enclosures 230,232,240 (e.g. not all enclosures 230, 240, 232 may comprise a lure unit, but only an enclosure where the luring of fish thereto is desired) and in some examples the fish farm may not require any lure arrangements to be contained therein. The lure units 245a-c may be attached to the nets forming the enclosures 230,232,240, may be attached to the floating structure 101,102,103 introduced in Figure 1, may be connected to the access arrangement 250 or may be suspended in lines from nets, e.g. those nets forming the enclosures in the fish farm 200, or suspended from the structure. The lure arrangement 245 a-c is designed for luring the fish thereto, e.g. by distributing a supply of fish feed, by providing an oxygen supply, by providing access to air for swim bladder adjustment, by shining a light on the fish, on an area of the enclosure or on the water surface, by using sound signals or by releasing an attractive or repulsive smell, or by using a fluid propeller to create a fluid flow, which may lure the fish thereto as a result of a natural desire to swim against a flow of water – the fluid flow may be directed through an access arrangement 250, for example which may then encourage a fish to swim from one enclosure to another separate enclosure via the access arrangement. For example, the lure arrangement 245a-c may be in the form of a lamp or light source, for example an ultraviolet light source, to which fish may be attracted. A fish may be attracted directly to a light source, or may be attracted to light from the light source reflecting off a water surface in the fish farm, or to an area inside the fish farm that is lit up. Alternatively, the lure arrangement may be in the form of a supply of fish feed, a pocket of air, or a combination of all of the aforementioned. As well as using attraction to move fish inside the fish farm 200, the lure arrangement may also use repulsion, or a combination of both attraction and repulsion to move the fish in the fish farm 200. For example, access to an air supply or air pocket may be blocked or restricted in one enclosure, thereby repelling a fish away from one enclosure into another, where an air supply or air pocket may be more regularly available. Additionally, sound or light may be used that are unpleasant to a fish, thereby encouraging the fish to move away from the vicinity thereof.

In some cases, the fish may be starved for a period of time (e.g. a meal, a day or a few days) in one enclosure in order to increase the efficacy of a lure comprising a fish feeding system located in a separate enclosure. In some examples, a sound may be played to the fish before feeding, thereby training the fish to associate being fed with a sound. As such, the feeding sound may be used itself as a lure, once the fish associate the feeding sound with being fed. The lure arrangement 245a-c may be able to be selectively activated, to lure fish only when desired. For example, where the lure arrangement 245a-c is or comprises a light source, a user or a control system may be able to turn the light source on and off if desired. Where the lure arrangement 245a-c is or comprises a source of fish feed or a pocket of air, selective access may be able to be provided to the fish feed or pocket of air by containing the fish feed and/or air in a selectively accessible compartment, access to which is controlled by a user opening, for example, a door or hatch. The lure arrangement 245a-c may be able to be remotely activated by a user, for example by using wireless communication, or a wired electrical connection extending to the surface of the fish farm 200, or may be controllable by mechanical means, such as by pneumatic or hydraulic means actuated by valves, pumps etc. For example, an air pocket may be filled or replenished with air provided in a conduit by mechanical means, or a mechanical feeding device may be operated by provision of hydraulic fluid thereto. In some examples, each enclosure may comprise the same lure arrangement 245a-c or combination thereof (e.g. a combination of a light source and fish feed) or some or all of the enclosures 230,232,240 may comprise differing lure arrangements 245a-c.

In the example of Figure 2, the fish are held mainly in the first and third enclosure 230,232 – e.g. the fish may be held in the first and third enclosures 230, 232 in the long-term, or for a longer period of time, and may only be held in the second enclosure 240 for shorter periods of time, such as when it is desired to remove some or all the fish from the fish farm 200, or when there is a desire to starve only a portion of the fish in the fish farm. The second enclosure 240 is arranged above the first and third enclosure 230,232 and has a cuboidal shape, although it should be noted that other shapes may also be possible, such as a cylindrical shape, or any other shape that is desired by the user. The shape of the second enclosure 240 may be at least partially defined by the floating structure 204, as in this example the third enclosure 232 is contained therein, and in cases where a sliding bulkhead is used (as will be described in later sections), it may be beneficial having a shape with at least one uniform crosssection. In some examples, for example when the second enclosure 240 can be raised to a level above the waterline (e.g. by de-ballasting the support structure) then it may be beneficial to have a shape with a vertically reducing cross-sectional area, such as an inverted pyramid or cone, as this would facilitate crowding the fish towards a single point in the second enclosure for extraction therefrom.

As previously described, the second enclosure may be made from a flexible net structure that is supported by ropes or ties, or may be made from a collection of rigid net panels to form a rigid frame structure, with netting located in the frame openings. In some examples, the second enclosure 240 may be made from rigid panels (e.g. of steel or plastic) which may be water permeable, or in some examples the rigid panels may not be water permeable, in which case a water circulation system may be provided, for example through use of a fluid pump arrangement. The size of the second enclosure 240 relative to the floating structure 204 may permit the second enclosure 240 may be held below the water surface.

The first and third enclosure 230,232 in this example also comprise a cuboidal shape with a pyramidal lower section at their bottom part. However, in another example, the enclosures 230,232,240 may have another shape, such as that described in relation to Figure 1 (e.g. a cylindrical shape). Herein the second enclosure 240 is formed by a net structure, the net structure being connected with connectors such as ropes to the floating structure 101,102,103 to apply tension to the net structure and hold it in place/shape relative to the floating structure 204, although in some examples, the second enclosure 240 may be directly connected to the floating structure 101, 102, 103. Having a second enclosure may permit the fish farm 200 to be used to separate a portion (e.g. some) of the fish therein, for harvesting, without having to harvest all the fish therein at one time. This may enable the overall size of the fish farm to be increased, as there is no need to harvest all the fish at once and limit the farm to the number of fish which may be harvested on a single vessel. This also means that it is not necessary to starve all the fish in the first enclosure prior to extraction of only a portion of the fish.

Although illustrated is a location above the first enclosure 230 and the third enclosure 232, the second enclosure 240 may also be located to one side of the first enclosure, at the same height thereof. In some examples, the second enclosure, or at least part of the second enclosure may be located adjacent (e.g. at the side of) the first and/or third enclosure, and inside an outer enclosure 211, e.g. an outer net (illustrated in broken outline in Figure 2) which may be used as a barrier to stop the escape of a fish, should there be a breach in one of the enclosures (similar to the second net 111 illustrated in Figure 1).

In the example illustrated in the disclosure of Figure 2, fish are grown in the first and third enclosure 230,232. The second enclosure 240 may enable the selection of a number of fish from the first and second enclosure 230,232, for grouping the selected fish based on some characteristic thereof and optionally for removing said selected fish from the fish farm 100. In another example the arrangement of the enclosures 230,232,240 may differ, e.g. the enclosures may be arranged side by side or the function of the enclosures may differ.

Figure 3 illustrates the process of fish being lured into the second enclosure 240. Here, the access arrangement 250 is configured to an open position to permit fish access through at least one of the access units 251, 252 into the second enclosure 240. It may be beneficial to be able to open each of the access units 251, 252 individually, to permit selective access between the second enclosure 240 and either one or (if desired) both of the first and third enclosures 230, 232. In some examples, it may be beneficial to provide a sequential opening of the access units 251, 252, for example to move fish from the first enclosure 230 to the second enclosure 240, and then from the second enclosure 240 to the third enclosure 232.

The second enclosure 240 may be smaller than the first and third enclosures 230,232 as shown in this example, thereby enabling only some of the fish in the fish farm to move into the second enclosure 240, effectively selecting those fish from the fish held in the first and third enclosure 230,232. After a desired number of fish have been lured into the second enclosure 240, the access arrangement 250 may be closed such that it blocks the access through the access units 251,252 into the first and third enclosure 230,232, trapping the fish in the second enclosure 240. The fish in the second enclosure 240 may then be optionally starved and extracted from the fish farm 200, e.g. for slaughtering or for moving to another fish farm.

Figure 4 illustrates a step in a method of operating a fish farm 200. In the illustration of Figure 4, after luring the fish into the second compartment 240 as described in relation to Figure 3, access through the access arrangement 250 is restricted by a restrictor arrangement 260 to selectively restrict/permit access of fish between the second enclosure 240 and the first and third enclosure 230,232 (e.g. from the second enclosure 240 to the first or third enclosure 230, 232). The restrictor arrangement 260 may be configured to allow smaller fish to pass therethrough, for example by providing an opening or openings that are sized to allow only smaller fish to pass therethrough. In an example where fish of any size have been permitted into the second enclosure 240, using a restrictor arrangement 260 to permit only fish below a certain size from passing therethrough has the effect of trapping the larger fish in the second enclosure 240 as shown in Figure 4. This may be useful as it may permit a group of larger fish to be held in the second enclosure 240, for example for harvesting, while harvesting of fish that are too small is avoided.

The restrictor arrangement 260 may comprise multiple restrictor units 261,262 as shown in Figure 4, herein comprising a unit 261 at the access unit 251 and another unit 262 at the access unit 252. As shown, the restrictor arrangement 260 may be located inside the access arrangement 250. In another example, the restrictor arrangement 260 may be attached to the access arrangement 250 e.g. at an opening of the access arrangement or may be located separated from the access arrangement 250. The restrictor arrangement 260, more precisely the restrictor unit 261, is introduced in detail in Figures 5a-c.

The luring arrangement may be utilized to lure the smaller fish back into the first and third enclosure 230,232 by disabling the luring unit 245b and activating the luring units 245a,c, as well as to lure fish in to the second enclosure 240, or by changing from an attraction lure to a repulsion lure, thereby encouraging fish that have been lured into the second enclosure 240 to leave. As shown in Figure 4, then only the larger fish remain in the enclosure 240 enabling to select fish for extraction by size. This may be beneficial, when extracting only the largest fish from the fish farm 200 while leaving the smaller fish thereby permitting them further time to grow to a desired size before extraction. The described method may not only enable extraction without harming the fish, as the fish are not physically stressed or forced during the selection process, but also enables the selection of a desired group of fish to be extracted, i.e. the fish which have grown big enough, to prevent extraction of fish which may be too small for further sale/processing, or which may not be able to be sold for a high price.

Figures 5a-c show an access unit 251 of the access arrangement 250 and a restrictor unit 261 of the restrictor arrangement 260 in further detail. On the left side of each Figure, a sectional side view on the access unit 251 and the restrictor unit 161 is illustrated. On the right side of each Figure, an elevation view is provided. The restrictor unit 261 is arranged inside the access unit 251. The access arrangement 250 may comprise multiple access units 251 similar to that described, or only a single one. The restrictor arrangement 260 may comprise a restrictor unit 261 located in each access unit 251 of the access arrangement 250, or in some examples, the fish farm 200 may comprise an access arrangement 250 or access arrangements 250 that do not comprise a restrictor arrangement 260 for cases where access is required, but with no requirement for size restriction.

The access unit 251 illustrated comprises a first access port 255 and a second access port 256 in the example of Figures 5a-e. As described in reference to in Figures 2-4, the first access port 255 is located in the first enclosure 230 and the second access port 256 is located in the second enclosure 240. Here, the access unit 251 comprises a hollow shaft that connects the first access port 255 to the second access port 256, thereby connecting two enclosures between which the access unit 251 is located, such as the first and second enclosure 230,240. In some examples, the access unit 251 may be or comprise a pipe or a hose to connect the first and second enclosure 230,240, for example in situations where the first and second enclosures are not immediately adjacent.

The restrictor unit 261 comprises a plurality of restriction members, in this example in the form of rigid bars with spaces therebetween for permitting a fish to pass therethrough. In other examples, the restrictor unit 261 may comprise a single restriction member, and/or the restriction member or members may be in the form of a panel(s), plate(s) or bar(s). As shown in Figures 5a-e, the restrictor unit 261 comprises two sets of restriction members 264,265, a first set of restriction members 264 shown in an upper position in Figures 5a-e and a second set of restriction members 265 shown laterally offset from the first set of restriction members 264 in a lower position. The sets of restriction members 264,265 comprise spaces between the members to permit a fish to pass therethrough. In this example each of the members are the same size and are equally spaced. However, in some examples, the members may not be equally sized and/or may not have equal spacing, such that at least two of the spaces between each of the members may differ. The first set of restriction members 264 is slidably moveable relative to the second set of restriction members 265 between an open position and a closed position. To achieve this, either the first or the second set of restriction members 264, 265 may be moveable, or both sets of restriction members may be moveable. The open position is shown in Figure 5b, herein the first and second set of rigid bars 264,265 are axially aligned, such that the fish may pass through the space between the first and second set of restriction members 264,265. The closed position is shown in Figure 5a, in which the first set of restriction members 264 is aligned with the spaces of the second set of restriction members 265, thereby preventing passage of a fish therethrough. Shown in Figure 5c is a third configuration, in which the first set of restriction members 264 has a partial overlap with the second set of restriction members 265, thereby reducing the space available for passage of a fish therethrough. This third configuration may be used when selecting fish according to their size as described with reference to Figure 4 as a larger fish may be unable to swim through the passage while a smaller fish may be able to do so. In the case where the restriction members 264, 265 are in the form of plates, the plates may be oriented at an oblique angle relative to the direction of motion, which may assist to provide a partial overlap between the restriction members 264, 265 when a degree of size restriction is required.

In this example the restriction members within each set of restriction members 264, 265 are parallel to one another. Similarly the restriction members of the first and second set of restriction members 264,265 are parallel to one another. In another example the restriction members may be in a different configuration, e.g. each set of restriction members 264,265 may form a grid structure, rather than being elongate and parallelly disposed, or the restriction members may be positioned with the longitudinal axis of one set of restriction members 264 being oblique e.g. angularly displaced relative to the second set of restriction members 265. In this example the first set of restriction members 264 is slidably moveable relative to the second set of restriction members 265 in a direction perpendicular to the longitudinal axis of the restriction members e.g. such that motion of the first set of restriction members 264 is parallel to the motion of the second set of restriction members 265, such as motion located in parallel planes. In some examples, the first set of restriction members 264 may be moveable relative to the second set of restriction members 265 in a direction of the longitudinal axis of the restriction members or in both the direction of the longitudinal axis, and in a direction perpendicular to the longitudinal axis as previously described. The first and/or second set of restriction members 264 may be remotely moveable by a user or may be moveable by a control system controlling the operation of the fish farm 100. An actuator may be connected to either one or both of the first and/or second set of restriction members 264, 265 depending on which of the sets of restriction members are to be moved. The actuator may be in the form of a remotely (e.g. wirelessly) operated motor, or may comprise a mechanical connection to the surface, allowing a user to move the restriction members if necessary.

The access unit 251 and the restrictor unit 261 may be arranged in the vicinity of an air pocket structure 270, and in some cases the air pocket structure 270 may incorporate a structural engagement with the access unit 251 and/or restrictor unit 261. The air pocket structure may comprise an accumulation of air 271, to be held in a subsurface location, as illustrated by the location of the access units 251 in the Figures. The accumulation of air 271 is located in contact with the water 273 inside the first enclosure 230 via a water-air-interface 272.

The fish may be able to see the water surface at the interface 272 and be lured to the accumulation of air 271 for example as they may feel the need to adjust their swim bladder. By luring the fish to the air pocket structure 270, the fish will then be located in the vicinity of the access unit 251, and some fish may swim through the access unit 251, without the yet the need to utilise the lure arrangement.

In another example the air pocket structure 270 may be considered to form part of the lure arrangement, and may enhance the efficacy of the lure arrangement in a separate enclosure by encouraging fish to swim towards access to another enclosure, thereby making the fish more likely to be attracted to the lure in another enclosure. The air pocket structure 270 may be a location that is frequently visited by fish. Therefore, if the air is removed from the air pocket structure 270, or if access to the air pocket structure 270 is blocked, the fish may still be likely to swim to the structure, and then may swim through the access unit 251 in search for an air pocket in an adjacent enclosure. In some examples, a one-way opening may be used, such as an opening with a flapper structure or funnel structure, to prevent fish from returning to the previous enclosure once having moved through the access unit 251.

Figures 5d and 5e illustrate an example of an air pocket structure 270 with a sliding panel 277 that may be placed either over the access arrangement 251 (Figure 5d) or over access to the air pocket structure 270 (Figure 5e), in this example by a simple sliding motion. As such, the fish may approach the air pocket structure 270 seeking access to the air pocket. With access to the air pocket blocked, the fish may swim through the access arrangement 251 instead.

The fish farm 200 may comprise a sensor arrangement for measuring the quantity of fish moving through the access arrangement 250. Herein the sensor arrangement comprises a sensor 269 configured to count the number of fish passing through the access unit 251. The sensor arrangement may comprise a sensor at each access unit 251,252 of the access arrangement 250, and thus the sensor arrangement may have a submerged location, as the sensor arrangement comprises a sensor at each access unit 251, 252 of the access arrangement 250. The sensor 269 may be a camera comprising image processor with a counter to count the number of fish passing through the access arrangement 250, and/or may comprise a photodetector and optionally a light source. In some examples, the sensor may provide information permitting a processing unit or a user to measure the size and biomass of each fish passing through the access arrangement 250 to calculate the number or mass of the fish currently passing through the access unit 251 or approaching the access unit 251 and for example, into the second enclosure 240. The sensor 269 or sensor arrangement may be or comprise an echo sounder for measuring the biomass of fish in the proximity of the sensor arrangement. Preferably the sensor arrangement, herein the sensor 269, is located adjacent at least one of the first and second access ports 255,256 thereby permitting the sensor arrangement to register each fish passing through the access arrangement 250. This may have the effect of reducing the measurement error when compared to methods that involve the observation (e.g. scanning) of large groups of fish in an enclosure, as the sensor arrangement is able to identify each fish as it passes through the access unit 251, and measure the mass of fish passing therethrough, thereby giving a better estimate of the biomass of fish in an enclosure. The efficacy of such a system may increase further when used in combination with the described fish farm 200 comprising at least a first and second enclosure, with the fish being lured from one enclosure to another, as the fish may pass more slowly and/or in a more organised manner than in fish farms that use other methods of moving fish such as physically forcing fish from one enclosure to the next. When fish are forced from one enclosure to the next, large numbers of fish may be pushed together, making counting of such fish difficult as well as estimating the biomass weight of the crowded fish. In the present disclosure, where the fish swim from one enclosure to the next to follow a lure, the fish may move more slowly through an access unit 251, thereby facilitating counting thereof, and additionally facilitating estimating biomass weight, identifying the ID and identifying the health condition of the fish.

The sensor data provided by the sensor arrangement 269 may be used by a user or a control system to provide control to the volume of biomass in each of the enclosures in the fish farm 200, for example in the second enclosure 240. In one example, the sensor arrangement 269 may provide an indication of the biomass in an enclosure, such as the second enclosure 240, such that a control system or a user may be able to operate a restrictor unit 261 or restrictor units accordingly. This may permit a biomass of fish, or a desired number of fish, to be contained within the second enclosure that is the same as the capacity of a vessel for removing the fish from the second enclosure.

In some examples, a combination of counting, and estimating the average biomass or weight of each fish passing by the sensor arrangement 269 may be used to calculate the biomass in an enclosure, which may be a quicker or computationally less demanding method of calculating the biomass. In a further example, the weight of each fish may be registered with a view to providing a statistical representation of the size of each fish that is being sensed by the sensor arrangement 269. In the case that too many fish that are being sensed by the sensor arrangement 269 are of an undesirable size and/or weight (e.g. are too small) then the restrictor unit 261 may be configured to prevent further access of fish into an enclosure, or the operation of the lure arrangement 245 may be changed in order to try to encourage movement of fish of a desired size/weight into the desired enclosure. In cases where the sensor arrangement 269 is capable of monitoring the health condition of a fish (e.g. where the sensor arrangement comprises a camera and health identification criteria), then the sensor arrangement 269 may be used to ensure that only fish of a superior health class are permitted entry into an enclosure (e.g. the second enclosure 240). Figure 6 shows a top view on the fish farm 200 of Figures 2-4, the fish farm 200 comprises a number of enclosures, in this example a first enclosure 230, a third, fourth and fifth enclosure 236,237,238 and a second enclosure 240 located above the other enclosures 230,236,237,238. The respective enclosures are connected to the second enclosure via the access arrangement 250 and the restrictor arrangement 260 comprising four access units 251-254 each with a respective restrictor units (not shown). Also shown are air pocket structures 270a-d, which may be integrated into the access units 251-254, as illustrated. The air pocket structures 270a-d and the access arrangement 250 and restrictor arrangement 260 may be connected to the floating structure 101,102,103. As illustrated, the second enclosure 240 is located towards the centre of the fish farm 200, which may assist to protect fish in the second enclosure 240 from predators, or harsh sea conditions, and ensure that there can be access to the second enclosure 240 from each of the first, third, fourth and fifth enclosures 230, 236, 237, 238. It should be noted that, although the second enclosure 240 is illustrated as a single enclosure, it may be possible to have multiple sub-enclosures in place of one single second enclosure 240, or have the second enclosure 240 be formed of multiple parts where each part is an individual enclosure. The parts of the second enclosure 240 may be located above the first, third, fourth and fifth enclosures 236, 237, 238. In this case, there may be access arrangements positioned between each of the parts comprising the second enclosure 240, to enable a fish to move between each of the parts of the second enclosure 240 when necessary.

Figure 7 shows a side view of the fish farm 200 and in which the fish are being crowded in the second enclosure 240, which may be in addition to the method as previously described. When a desired number of fish has moved into the second enclosure 240, the access arrangement 250 and the restrictor arrangement 260 may be used to restrict at least some fish from moving back to the first and third enclosure 230,232, for example restrict the fish based on their size, as previously described. The second enclosure 240 may comprise a volume restriction device 280 for selectively reducing the volume of space available to a fish therein, thereby crowding the fish in the second enclosure 240 and facilitating extraction therefrom.

Figures 8-14 show an example of a volume restriction device 280 and component parts thereof which may be installed in the second enclosure 240. The volume restriction device 280 in this example is a sliding bulkhead 282. The second enclosure 240 comprises a first engagement profile 284, in this example comprising an elongate engagement member, and the sliding bulkhead 282 being installed in the second enclosure 240 comprises a receiving profile 285 forming the counterpart to the engagement profile 284, the receiving profile 285 being in the form of a recess in the bulkhead 282. The profiles 284, 285 are configured to fit together and enable a sliding movement of the sliding bulkhead 282 through the second enclosure 240. The sliding bulkhead 282 may comprise a net material. In some examples, the volume restriction device 280 may comprise a net or a wall, may be rigid or flexible, and may be permeable to water, while restricting movement of a fish. In some examples, the volume restriction device may be installed in any or all of the enclosures, e.g. the first, second or third enclosure 230,232,240. The first profile 284 may comprise multiple elongate members arranged in (e.g. along a wall of) the second enclosure 241 forming a rail for the second profile 285 to slide along as shown for example in Figure 9. The engagement profile 284 may comprise a male connector part being connected to and extending from the wall of the second enclosure 241 being interlockable with a female connector part of the receiving profile 285 as is shown in Figures 10-12. In other examples, the engagement profile 284 may be the female profile, while the receiving profile 285 is the male profile.

Figure 13 shows the volume restriction device 280 from a side perspective with a wall of the second enclosure 241 shown. The volume restriction device 280, herein the sliding bulkhead 282, may be connected to the wall of the second enclosure 241 by multiple interlocking profiles 284,285 as is illustrated. Preferably, the receiving profile 285 is large enough compared to the size of a single member of the engagement profile 284 so that it cannot disengage or fall off the guiding engagement profile 284 as shown in Figure 14. The sliding bulkhead may have only small openings towards the walls of the second enclosure 241 to prevent fish from passing through the openings and moving to the other side of the sliding bulkhead 282. In some examples, the sliding bulkhead 282 may comprise brushes installed along an edge thereof, at the interface between the bulkhead 282 and the second enclosure, to close any gaps between the bulkhead 282 and the walls of the second enclosure 240, thereby assisting to prevent a fish entering the gap between the bulkhead 282 and the second enclosure 240. Although not illustrated, lines may be attached to the sliding bulkhead 282 to facilitate movement of the sliding bulkhead. The lines may be connected to winches, which may be located on the floating structure 204, for example. Other means of movement may also be possible, such has having a rack and pinion engagement between the sliding bulkhead and the enclosure, using hydraulic cylinders or a worm gear to move the bulkhead.

In cases where the sliding bulkhead is not in use, or is not needed to crowd the fish, the sliding bulkhead may be positioned within the second enclosure 240 in order to form a partition in the second enclosure 240, thereby effectively separating it into two sub-enclosures. The bulkhead may be installed in this position as a temporary measure, or over a longer period of time.

In other cases, the sliding bulkhead may be able to be temporarily installed in an enclosure, such as the second enclosure 240. For example, where it is known that fish are to be crowded in the second enclosure (e.g. because fish are required to be moved from the second enclosure 240) then the sliding bulkhead may be temporarily installed in the second enclosure 240. This has the further advantage that the sliding bulkhead may be uninstalled for repairs or cleaning more easily.

Figures 15-17 show another application of the fish farm 200 according to the invention. In Figure 15 all fish in the fish farm 200 are located inside the first enclosure 230. However, the first enclosure 230 may require cleaning, repair/replacement of parts of an enclosure, or for another reason the fish might need to be moved to the third enclosure 232. The fish may be lured from the first enclosure 230 to the second enclosure 240 by opening the access unit 251 and restrictor unit 261 and activating the luring unit 245b as shown in Figure 16. When the desired number of fish are inside the second enclosure 240 (which may be all or some of the fish), the access unit 251 and restrictor unit 261 are configured to prevent access between the first and second enclosure 230,240. The access unit 252 and restrictor unit 262 are opened to enable the fish to swim into the third enclosure 232. The luring unit 245b of the second enclosure is deactivated and the luring unit 245c inside the third enclosure 232 is activated to lure the fish thereto. Figure 17 shows all the fish having arrived at the third enclosure 232. The access unit 252 and restrictor unit 262 may now be closed to keep the fish in the third enclosure 232. It should be noted that, while the luring unit 245b is illustrated as being located on the side wall of each enclosure in Figures 15 to 17, it may alternatively be located in any other appropriate location, such as on the floating structure 204.

Figures 18 and 19 show different options for extracting the fish from the fish farm 200 once a desired number of fish has been moved into the second enclosure 240. The second enclosure 240 is then able to be separated from the other enclosures 230,232 by closing the access arrangement 250 and the restrictor arrangement 260 and decoupling the second enclosure 240 from the remainder of the fish farm. In this example, the second enclosure 240 may be coupled to the fish farm 200 by a releasable fastening arrangement such as ties or releasable locks. Then the fish may be extracted from the fish farm by releasing the connection of the second enclosure 240 to the fish farm 200 and removing the second enclosure 240, e.g. by transporting the second enclosure to a nearby vessel. The net of the second enclosure 240 may be installed after extracting the fish therefrom or another net may replace the removed one, forming another second enclosure 240 at the fish farm 200 to enable further operation according to the disclosed methods. In another case the fish may be extracted by a suction pipe or hose 287, a suction device, an ROV, a robotic fishing arm or the like as shown in Figure 19, leading directly to a storage container on a vessel. In this example, the suction hose 287 is illustrated as being part of the fish farm 200, however in other examples the suction hose 287 may be provided on a vessel. Fish may be transported to the vessel (e.g. via the hose) and removed from the fish farm 200.

Figures 20 and 21 show methods of crowding the fish prior to extracting the fish from the fish farm 200. In operation of the fish farm, the enclosures 230,232,240 are preferably below the water surface which may reduce the impact of waves, predators and parasites such as sea lice on the fish population. The enclosures 230,232,240 may for example be five meters or more below the water surface. The enclosures 230,232,240 may be suspended from the floating structure or the floating structure may be itself below the water surface as shown in the illustrated examples. The floating structure, the enclosures 230,232,240 or both may comprise means to selectively alter the buoyancy, enabling to move any of them to the water surface, e.g. for crowding the fish, facilitating construction or facilitating maintenance and cleaning.

In Figure 20 the access units 251,152 and restrictor units 261,262 comprise extendible or flexible connections between the access ports 255,256 at the respective compartments 230,232,240 as introduced in Figures 5a-c. Utilizing the flexible connections, the second enclosure 240 may be moved towards the water surface, e.g. by lifting the second enclosure 240 with a hoist or other appropriate lifting device. Upon reaching the water surface, the fish are then able to be crowded between the water surface and the lower end of the second enclosure 240 as illustrated in Figure 20.

Figure 21 shows an example, wherein the whole fish farm 200 is moved towards the water surface by changing its buoyancy, e.g. utilizing pumps to pump ballast water out of the floating structure. Consequently, the second enclosure 240 is close to the water surface and similar to Figure 20 the fish will crowd between the water surface and the lower end of the second enclosure 240.

As seen in some examples, the fish farm of this disclosure is not limited to a single or two enclosures 230,232,240, but the person skilled in the art will understand to apply the inventive principle to fish farms of various sizes, structures and net arrangements.

Figure 22 illustrates an additional example of a fish farm 300, or part thereof. In this example, the fish farm 300 comprises a first enclosure 330 and a second enclosure 340 in common with previous disclosures. In contrast with the previous examples, here the entire of the first and second enclosures 330, 340 are contained entirely beneath the waterline 390, both being suspended by a floating structure 304, which in this example is in the form of a plurality of floating buoys connected to the first and second enclosures 330, 340 via mooring lines 358.

As in previous examples, the first and second enclosures 330, 340 may comprise nets, for example nets supported by frames, or may comprise panel members that are affixed together to form the first and second enclosures 330, 340, and which may be permeable to water. As in previous examples, the second enclosure 340 is located above the first enclosure 330, with the second enclosure 340 also being smaller than the first enclosure 330 in this example. Again, in common with previous examples there is an access arrangement 350, which may comprise a restrictor arrangement, and selectively enable fish to move from the first to the second enclosure 330, 340, and vice versa if desired. Here, the first enclosure 330 is directly connected to the second enclosure 340 directly, and the two are separated by a top net 306. Here, there is a lure arrangement 345a in the first enclosure and a lure arrangement in the second enclosure 345b which may be used to attract or repel a fish to/from each enclosure 330, 340.

Although not illustrated in Figure 22, in this example the fish farm 300 may comprise a floating collar, which may be positioned at the top of the second enclosure 340, or at the top of the structure comprising the enclosures in the case that the second enclosure is not positioned at the top of the enclosure structure. The floating collar may be able to be ballasted and deballasted, which may be useful if there is a requirement to bring the enclosures 330, 340 to the waterline 390 (for example for removing the second enclosure 340), or to lower the enclosures 330, 340 further below the waterline 390, for example to provide additional protection against sea lice, waves, surface predators, etc..

As in previous examples, the first and second enclosures 330, 340 may comprise vertically oriented nets or permeable panel structures to divide the first and second enclosures 330, 340 into sub-enclosures.

The described fish farm 300 has a much simpler floating structure 304 as compared to other fish farms. As such, this fish farm 300 may be cheaper and quicker to construct and maintain than a fish farm 300 having a more complex structure 304.

The same fish farm 300 is illustrated in Figure 23, however in this example rather than being suspended from a floating structure 304 on the waterline 390. Instead, in this example the enclosures 330, 340 are suspended from below, for example from the seabed, on a cable 392. The cable 392 may be connected to a winch which may enable the fish farm 300 to be raised and lowered in the surrounding fluid. As in the previous example although also not illustrated, a floating collar may be positioned at the top of the second enclosure 340 (e.g. at the top surface) or at the top of the enclosure structure in the case that the second enclosure 340 is not located at the top of the structure. In Figure 24 is illustrated a further example of a fish farm 400. In this example there is a first and a second enclosure 430, 440, with the second enclosure 440 being located above the first enclosure 430, as in previous examples. Also similar to previous examples, an access arrangement 450 is positioned between the first and second enclosure 430, 440, with the first enclosure being directly connected to the second enclosure. In this example, the lure arrangement is in the form of a lure 445a in the first enclosure 430 and a lure 445b in the second enclosure 440.

Here, one of the first or the second enclosure 430, 440 is connected to a buoyancy structure 404 (illustrated the second enclosure 440 is connected) which floats on the water surface 490. As in previous examples, a top net 406 separates the first enclosure 430 from the second enclosure 440. In this example the top net 406 may be moveable, so as to vary the volume of space available in the first and second enclosures 430, 440. This may be useful to facilitate crowding of fish in either enclosure 430, 440, and may also enable the fish to be kept deeper in water if necessary, which may assist in avoiding sea lice or adverse weather/wave conditions. The top net 406 may be connected to a frame, which may assist to hold the top net 406 in a rigid configuration. The top net 406 may then be suspended from the buoyancy structure 404 by wires, which may be connected to a hoist arrangement for raising and lowering the top net 406. Alternatively, the top net 406 may comprise a rack and pinion style engagement with the first and second enclosures 430, 440, which may enable movement of the top net 406 relative thereto. In some examples, the top net may comprise a small motorised arrangement or hydraulic arrangement that may enable a user to move the top net 406 relative to the first and second enclosures 430, 440.

In some examples, rather than raising/lowering the top net 406, the entire enclosure structure may be raised and lowered 430, 440. As such, there may be a section of loose net (e.g. net that is not supported by a frame) along the length of the enclosure structure (e.g. adjacent the floating structure 404) that may be able to be expanded or contracted as needed. In this example, winches may be provided on the buoyancy structure 404 and cables may extend along the length of the enclosure structure in order to enable raising and lowering thereof.

Claims

1. A fish farm (200) comprising:

a first enclosure (230),

a second enclosure (240); and

the first enclosure (230) being connected to the second enclosure (240) by an access arrangement (250) for selectively permitting movement of a fish between the first enclosure (230) and the second enclosure (240); characterised in that

the first enclosure (230) and the access arrangement (250) is positioned within the fish farm (200) such that both the first enclosure (230) and the access arrangement (250) are fully submergible when positioned in a body of water.

2. The fish farm (200) according to claim 1, comprising a restrictor arrangement (260) in cooperation with the access arrangement (250) for selectively permitting access between the first and second enclosures (230,240).

3. The fish farm (200) according to claim 2, wherein the restrictor arrangement (260) is located in the access arrangement (250).

4. The fish farm (200) according to claim 2 or 3, wherein the restrictor arrangement (260) comprises a plurality of rigid bars with spaces therebetween for permitting a fish to pass therethrough.

5. The fish farm (200) according to any of claims 2 to 4, wherein the restrictor arrangement (260) comprises a first and a second set of rigid bars (264,265), each set having spaces therebetween for permitting a fish to pass therethrough, the first set of rigid bars (264) being slidably moveable relative to the second set of rigid bars (265) between an open position, in which the spaces between the rigid bars of the first and second set of rigid bars (264,265) are aligned, and a closed position, in which the rigid bars of the first set of rigid bars (264) are aligned with the spaces of the second set of rigid bars (265), thereby restricting passage of a fish therethrough.

6. The fish farm (200) of claim 5, wherein the first set of rigid bars (264) may be positioned relative to the second set of rigid bars (265) such that the bars of the first set of rigid bars (264) partially overlap with the spaces of the second set of rigid bars (265), thereby reducing the space available for passage of a fish therethrough.

7. The fish farm (200) according to any preceding claim, comprising a sensor arrangement (269) comprising a counter for counting the number of fish passing through the access arrangement (250).

8. The fish farm according to any preceding claim, comprising a lure arrangement (245) for motivating movement of a fish from the first enclosure (230) to the second enclosure (240).

9. The fish farm (200) according to claim 8, wherein the lure arrangement comprises at least one of: a supply of fish feed, an air pocket, a light, speaker/sound transmitter and a fluid propeller.

10. The fish farm (200) according to claim 8 or 9, wherein the lure arrangement is located in each enclosure (230,232,240) of the fish farm (200).

11. The fish farm (200) according to any of claims 9 to 11, wherein the lure arrangement is able to be selectively activated within an enclosure (230,232,240) of the fish farm (200).

12. The fish farm (200) according to any preceding claim, wherein at least one of the first and second enclosures (230,240) comprises a volume restriction device (280) for reducing the volume of space available to a fish therein.

13. The fish farm (200) according to any preceding claim, wherein both the first and second enclosures (230, 240) are contained within an outer enclosure (211).

14. A method for managing fish in a fish farm (200), comprising:

providing a first enclosure (230) and a second enclosure (240) the first enclosure (230) being connected to the second enclosure (240) by an access arrangement (250) for selectively permitting movement of a fish between the first enclosure (230) and the second enclosure (240); and

housing a fish in the first enclosure (230); characterised by

permitting a fish in the first enclosure (230) access to the second enclosure (240) by positioning the first enclosure (230) and the access arrangement (250) such that both are fully submerged when positioned in a body of water.

15. The method of claim 14, comprising using the lure arrangement to motivate a fish to move from the first enclosure (240) to the second enclosure (232).