NO346189B1

NO346189B1 - Fish farming system

Info

Publication number: NO346189B1
Application number: NO20200755A
Authority: NO
Inventors: Per Kristian Bruun; Svein Ersdal; Kristoffer Kjellså Jakobsen; Andreas Jo Falk Fredborg; Henrik Hannus
Original assignee: Aker Solutions As
Priority date: 2020-06-26
Filing date: 2020-06-26
Publication date: 2022-04-11
Also published as: NO20200755A1

Description

FISH FARMING SYSTEM

The present invention relates to a fish farm, and particularly to a semi-submersible offshore fish farm.

BACKGROUND

The recent years have seen a considerable growth in the fish farming industry in various countries, and it is projected that fish farming will continue to play a key role in the provision of food in the future. A continual focus on safety, fish welfare and the environmental impacts of fish farming, however, drives a demand for improved methods and solutions for fish farming. Various such improvements have been suggested over the recent years.

For conventional fish farming, there exists several types of fish pens, but the most common technology for salmon farming is to use a floating flexible collar with a suspended net. The fish pens are often moored in a grid mooring system. A nearby feed barge may be used for providing the required support systems for the fish pens.

Due to the continuous increasing demand for sea food and the limited number of sheltered locations suitable for fish farming, there is a need to develop new solutions that can, for example, be used outside these sheltered areas, where environmental influence may be more severe, or which provide advantages in relation to production efficiency, fish welfare, or other parameters.

Publications which may be useful to understand the field of technology include WO17153417A1, WO 2019093903 A1, NO 158401 B, NO 166511 B, NO 343123 B1, US 4744331 A, SE 459139 B, NO 344480 B1, NO 343071 B1, and NO 342421 B1.

The objective of the present invention is to provide systems and methods which further improve on conventional solutions and techniques in the above or other areas.

SUMMARY

According to the invention, there is provided a fish farming system comprising a polygonal shaped floating collar and a plurality of enclosures for fish suspended from and supported by the floating collar. Each of the plurality of enclosures are configured to be fully submerged in an operating state of the fish farming system, and the floating collar for each of the plurality of enclosures comprises a respective air pocket defined by and incorporated in the floating collar and arranged inside the enclosure.

Various embodiments are outlined in the following detailed description and appended claims.

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:

Fig. 1 shows a perspective view of a fish farming system.

Fig. 2 shows a cross-section of the fish farming system of Fig.1.

Fig. 3 is a plan view of a fish farming system.

Figs.4 and 5 are elevation and plan views of the fish farming system of Figure 3 showing operations performed within the system.

Figs.6 to 9 are perspective views showing various aspects of collars for fish farming systems.

Figs.10 to 12 illustrate a further example of a fish farming system having a triangular shaped collar.

Fig. 13 is a top view of a fish farming system in an embodiment.

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.

Aspects of the present disclosure relate to a fish farming installation with a semisubmersible floating collar for a submersible fish pen. This installation may operate on two or more operational drafts such that the top of a net cage can be in a surface or near-surface position, or completely submerged. The top of the net cage can, for example, be submerged to a depth of 5-10 meters or more below the water surface, in order to reduce the exposure to, for example, sea lice, algae, and jellyfish and also reduce the environmental loads from ocean currents and waves or from impacts from floating objects. The installation may optionally be designed for deeper submergence to further reduce environmental loads.

The fish farming system may be designed with a favourable ratio between water line area and displacement to provide an effective construction for handling bending moments from waves and ocean currents, less movement of the floating collar during bad weather conditions. Since the effect of waves tends to be less in deeper water, less movement will be transferred from the floating collar to the net cage, which in turn reduces the change of damage to the net cage and escape of fish.

A semi-submersible fish-farming system, such as a fish pen, according to aspects described herein may be operable between at least two different semi-submerged positions, a first position and a second position, by ballasting and de-ballasting. The system may comprise a rigid floating collar comprising a ring-shaped or polygonal lower buoyancy member, a ring-shaped or polygonal upper buoyancy member, a plurality of columns connecting the buoyancy members, a net cage suspended from the floating collar and a net roof closing off the top of the net cage, the net cage with the net roof forming an enclosure for fish.

Fig. 1 is a principle drawing showing some elements of a fish farming system according to an aspect and Fig.2 is a cross-section of the system shown in Fig.1. In a preferred embodiment, the system comprises a fish pen 1 with a floating collar 2 comprising a lower buoyancy member 7, an upper buoyancy member 9 and a plurality of columns 8 which are mounted to the lower buoyancy member 7 and the upper buoyancy member 9. The columns 8 connect the lower and upper buoyancy members 7,9. The upper and lower buoyancy members 7,9 and columns 8 are preferably made of a rigid material, such as steel. For additional stiffness, for example to restrict torsion, bending or shear, tie struts or plates may be placed between some of the columns. The upper and/or the lower buoyancy members 7,9 can, for example, have a circular or polygonal shape.

The lower buoyancy member 7 is a continuous, closed pontoon encircling the central portion of the fish pen 1 in which a net cage 3 is suspended, the net cage 3 forming an enclosure 3 for the fish and the net cage 3 being supported by the floating collar 2. The enclosure 3 is defined by sides 4 and a bottom 44, either or both of which can be flexible, such as a pliable net, or a stiff or semi-stiff construction. Further, the enclosure 3 can have a closed roof 5, arranged to close a top section of the enclosure 3, thereby preventing fish from leaving the enclosure 3 and/or preventing predators from entering the enclosure 3. The roof 5 may be a net, grid, or other suitable arrangement. The roof 5 may be of the same material as the sides 4 and/or bottom 44. Even if phrased a "net" here, this does not preclude other types of materials used in the roof 5, sides 4 or bottom 44. These elements can be separate elements or an integrated construction. The enclosure 3 may also comprise a bottom ring 26, which may be temporarily or permanently installed and which can be pulled towards the surface using winches and wires or other mechanical means for example for fish crowding. The bottom ring 26 may also provide weight to keep the enclosure 3 in a desired form (e.g. keeping the sides 4 substantially vertical), and it may be arranged semi-stiff or stiff in order to assist keeping the shape and form of the enclosure 3 in the case of water currents or other loads.

The bottom ring 26 may be connected to an outer net, an inner net, or both an outer and an inner net defining the enclosure 3, described in further detail below. In such a case, the bottom ring 26 may be arranged to support either the outer net or the inner net, or both the outer net and the inner net.

The lower buoyancy member 7 can, for example, have a circular, square, hexagonal or octagonal design. The cross-section of the lower buoyancy member can for instance be circular, square or have another form. The interior of the lower buoyancy member 7 can, for example, be divided into one or more sections by means of partition walls. Further, the cross-section area and shape of the lower buoyancy member 7 does not need to be uniform. The upper buoyancy member 9 may have any of the above stated configurations and may also have a different design compared to the lower buoyancy member 7. The upper buoyancy member 9 and/or the lower buoyancy member 7 may be arranged with dedicated space for storage, operational equipment or the like. Such space may, for example, be in one or more partitioned sections in the structure.

The cross-section of the columns 8 can be circular, square or any other shape. Further, the columns 8 can each be identical or have different sizes and crosssections. The distance between the columns 8 can be uniform or varying. The distance from a column 8 to the centre of the fish pen 1 can also be uniform or varying. The interior of at least some of the columns 8 is preferably in fluid communication with the interior of the lower buoyancy member 7. For trimming, water may be supplied or removed from the interior of the lower buoyancy member 7 and possible also the interior of some or all the columns 8. There may, optionally, be not multiple, but only one single column connecting the lower buoyancy member 7 and the upper buoyancy member 9.

The interior of one or more of the columns 8 may be may be arranged with dedicated space for storage, operational equipment or the like. One or more of the columns 8 can, for example, be divided into one or more sections by means of partition walls for this purpose. Such space may, for example, be in one or more partitioned sections in the structure.

To lower the fish pen 1 to an operational or submerged position 16, wherein the water line at the operational or submerged position 16 is indicated, water can be pumped into the interior of the lower buoyancy member 7 and possibly also into whole or parts of some or all of the columns 8, until the desired draft is achieved.

The interior of the upper buoyancy member 9 and/or the columns 8 or parts thereof can, if desirable, be closed and filled with air or a foam material that provides buoyancy when the fish pen 1 is submerged. In this position, the roof 5 of the enclosure 3 can be kept at a certain depth to avoid or reduce the exposure to sea lice, jellyfish and algae. By submerging the enclosure 3, also the environmental impact of waves and currents can be reduced, since these impacts in general are more pronounced at or near the water surface and are reduced with increasing depth. By submerging the enclosure 3 a distance below the water surface, the movements transferred to the enclosure 3 from the collar 2 can also be reduced and the risk for damaging the enclosure 3 and escape of fish be reduced, due to less movement of the floating collar 2 and consequently less movement of the enclosure 3.

In order to raise the fish pen to a service position 15, wherein the water line at the service position 15 may be as indicated in Fig.2, water can be pumped out of the lower buoyancy member 7 and/or the columns 8. The service position 15 may be a position wherein the lower buoyancy member 7 is at or near the water surface. In the service position 15, the floating collar 2 may then be floating with the lower buoyancy member 7 on the water surface such that the roof 5 of the enclosure 3 can be at or above the water surface. By removing the roof 5 (or parts thereof) of the enclosure 3 when the floating collar 2 is in service position 15, access to the enclosure 3 can be obtained for inspection, maintenance and different operations such as crowding and delousing. The upper buoyancy member 9 can function as support for travelling cranes, winches, personnel basket to facilitate operations in enclosure 3. All necessary tubes, hoses, cables etc. can be connected to the upper buoyancy member 9, led down the columns 8 to the lower buoyancy member 7 and out into the enclosure 3. Consequently, there is no need to take the enclosure 3 to surface for inspection or connection and the operation is not relying on divers/ROV.

The construction of the fish pen 1 may be so robust and strong that it is possible to utilize a direct-coupled mooring system 22 (see Figs 1-2) and it is not necessary to use a frame mooring, such as used for conventional systems with flexible plastic rings. This involves that each individual fish pen 1 can move independent of each other, if more fish pens 1 are placed in the same area, and the distance between each fish pen can be larger for increased safety and improved water quality.

In any of the embodiments described herein, the floating collar 2 may, alternatively or additionally, be configured for changing the vertical position by means of for example a pull-down mechanism, such as a winch arranged at the sea floor or a winch arranged elsewhere which provides a pull-down force via a wire and a sheave mechanism at the sea floor. Such a pull-down mechanism may operate as the main mechanism for adjusting the vertical position of the floating collar 2 in the water, or it may operate in conjunction with ballasting of the floating collar 2.

Illustrated in Figures 3 to 12 is an embodiment of a fish farming system 1 that comprises a polygonal shaped floating collar 2 and a plurality of enclosures 3a-d for the containment of fish therein. The plurality of enclosures 3a-d are supported by the floating collar 2, and the collar 2 additionally comprises an air pocket 220a-d that is arranged at least partially within the enclosure 3a-d.

According to the example shown in Figures 3 to 9, the collar 2 has a square or rectangular shape, as can be seen clearly in Figure 3. The collar 2 is made up of four side members 2a-d that form a square or rectangular frame. In the centre of the collar 2 formed by the side members 2a-d is a recess, which is divided into quadrants 3a-d. In use, fish are contained within the recess formed by side members 2a-d, and in this example fish may be contained in one, some or each of the four quadrants 3a-d. Each of the four quadrants 3a-d may be separated by a partition, which may be in the form of a net, plate, grid or the like. The partition may be a stiff partition, such as a rigid grid, and/or a flexible partition such as a pliable net structure.

Incorporated in the square/rectangular collar 2 is an air enclosure or air pocket 220a-d which may extend downwardly from the collar, and may provide fish that are contained in the quadrants 3a-d access to a water surface and air also when the collar 2 is in a submerged state and the roof 5 is located a distance below the waterline 201. This may be seen most clearly in Figure 4. The air enclosure may thus hold a bubble of air in a location that is below the waterline 201. The fish farming system 1 may comprise means to replenish the bubble of air, if and when it is depleted, such as an air compressor and appropriate air supply pipes into the air pocket 220a-d.

In Figure 4, there is illustrated a side elevation view of the fish farming system 1 of Figure 3. Here, two of the quadrants 3a, 3b can be seen in their location below the waterline 201. Here, the outer bounds of the quadrants 3a-d may be formed by any appropriate material, such as a net, mesh, plate, etc., and in some cases may be held taught by a weight 228. In Figure 4 it is illustrated that the outer bounds of the quadrants 3a-d may be extended as shown with quadrant 3a, by providing a downwards force on the outer bounds material, for example in the direction of the arrow shown. The lower part of the enclosure 3a may be permanently held in a cone shape by a weight suspended below the enclosure 3a. In quadrant 3b is illustrated a means for crowding fish in quadrant 3b, which may involve sweeping a crowding device, such as a net, up from the bottom of the quadrant 3b. A similar principle is illustrated in Figure 5 in quadrant 3b, although in this case the crowding device is swept horizontally through the quadrant 3b.

Illustrated in Figure 6 is a three dimensional structure of the collar 2 of an example of the fish farming system 1. The collar 2 comprises side members 2a-d and air pockets arranged as a part of corner structures 225a-d. There is an area of overlap between each of the air pockets 220a-d and their respective quadrant 3a-d, which may enable any fish or other sealife in the quadrant 3a-d access to the air pocket 220a-d. Similarly, the air pockets 220a-d may provide an operator access to the quadrants, for example for providing food into the quadrant, or for introducing tooling, netting, measurement equipment, medication, or other things into the quadrant.

Also illustrated in Figure 6 are connection members 223, in this example in the form of beams, that connect each of the side members 2a-d together and provide a rigid structure for the collar 2.

Illustrated in Figure 7 is a similar collar 2 to that shown in Figure 6. As such, alike features will not be described again. In the example of Figure 7, the side members 2a-d are connected by cables or ties 223 that are held in tension. The cables or ties 223 may be tightened until each is under sufficient tension to hold the collar 2 together as a rigid structure. Using tension members such as cables 223 as illustrated may provide a cheaper and lighter option for construction of the collar 2 than in other examples.

The air pockets 220a-d illustrated in Figure 7 are located on the lower buoyancy member and are confined to a subsea location under the waterline 201. In the case of Figure 7, a channel or opening may extend through the collar 7 to the air pocket, to permit access to the air pockets 220a-c if necessary. Figure 8 illustrates a further view of one of the air pockets 220 from below the collar 2. It is illustrated that the air pocket consists of a hollow housing in which air may be captured and stored for access by fish in the enclosure 3a-d.

Figure 9 illustrates a further example of a collar 2, having air pocket(s) in the centre of the collar, in a centre structure 222. The air pocket(s) in the centre structure 222 may be a single air pocket accessible from all enclosures 3a-d, or it may be several separate air pockets. In this example, the four air pockets, which in previous examples were located at each corner of the polygonal collar 2, are now located together in one central structure. Optionally, the collar 2 may have air pockets both in a central structure and along the outer structure of the collar 2.

In all embodiments, the air pocket(s) may have an access point within the collar structure from a position located above the water line 201. This may be used to provide access to the fish farm system 1 below the waterline 201, for example into the quadrants 3a-d. As such, the collar 2 may provide a hatch or opening (not shown) in any of the examples described herein, for such access.

Figures 10 to 12 illustrate a further example of a fish farming system, this time having a collar 2 that is substantially triangular in shape. The collar 2 comprises three sides 2a-c and a centre structure 222. The centre structure 222 is connected to each of the three sides by connection members 223. Together the centre structure 222 and the connection members define three separate enclosures 3a-c. In this example the three separate enclosures 3a-c are separated from one another by netting, which is suspended from the collar 2. In line with previous examples, and although not illustrated in Figure 10, the central structure 222 may comprise an access port such as a hatch or opening through which a user may be able to gain access to each of the enclosures 3a-c, for the provision of food to the enclosures, or for the introduction of tooling into the enclosures 3a-c.

As described in relation to previous examples, the collar may comprise a lower buoyancy member 7 and an upper buoyancy member 9 which are connected together via a plurality of columns 8. The three separate enclosures 3a-c can be suspended from the lower buoyancy member 7.

The centre structure 222 is in this embodiment in the form of a vertically oriented cylinder (i.e. the axis of the cylinder is approximately vertically oriented) and in this example the cylinder has an enclosed upper surface.

The centre structure 222 may be attached to the collar at both the upper buoyancy member 9 and the lower buoyancy member 7 and extends therebetween.

Having a structure as illustrated may permit a fish farming system 1 that has multiple enclosures 3a-d, while also providing a robust collar 2, the structural integrity of which may be reinforced by the centre structure 222, while also permitting secure access to a source of air, without allowing the fish to escape or be exposed to aerial predators.

Illustrated in Figure 12 is an example of a farming system 1 that comprises mooring system, and is held in place by mooring lines 226. In this example, as the collar 7 is triangular in shape, there is a mooring support 224 located at each corner thereof. The mooring support 224 comprises a plurality of vertically extending bars that are attached to both the upper buoyancy member 9 and the lower buoyancy member 7. Mooring lines 226 attach the collar 2 to a location (not shown) which may be on the seabed, thereby restricting the movement of the system 1.

Illustrated in Fig.13, the connection members 223 may in any embodiment be arranged such as to span a central axis of one or more of the enclosures 3a-d. The central axis means a vertical axis extending from a midpoint of the enclosure or from a lowermost point of the enclosure, such as the tip of a cone-shaped bottom of the enclosure. The lowermost point can be effected by a weight suspended from the enclosure 3a-d, which may be a net structure. Reference is made also to Fig.4 which shows such a cone-type shape having a lowermost point for the enclosure 3a.

Having the connection members 223, which is this case can be any internal structure arranged in the collar 2 at any height (such as at the same height as the upper or lower buoyancy members 7,9 or at the same height as the columns 8) provides the advantage that access directly above the centrepoint of each enclosure 3a-d can be ensured. For example, it may be desirable to be able to raise or lower equipment directly vertically down to the lowermost point in the enclosure, for example to collect dead fish or to inspect the enclosure 3a-d.

The connection members 223 may be, for example, beams which allow an operator to walk on them, and/or allows equipment to be suspended from them, e.g. by a winch, sheave, or suspension / hang-off point.

Although not illustrated in relation to Figures 3 to 12, the upper and/or lower buoyancy members 9, 7 may comprise ballast tanks, as has been previously described, and therefore the buoyancy of the farming system 1 may be adjusted as necessary. Therefore, the mooring lines 226 may comprise a degree of slack to permit vertical movement of the system 1 without causing damage to the mooring lines 226.

The invention is not limited by the embodiments described above; reference should be had to the appended claims.

Claims

1. A fish farming system (1) comprising:

a polygonal shaped floating collar (2); and

a plurality of enclosures (3a-d) for fish suspended from and supported by the floating collar (2), each of the plurality of enclosures (3a-d) being configured to be fully submerged in an operating state of the fish farming system (1), characterised in that the floating collar (2) for each of the plurality of enclosures (3a-d) comprises a respective air pocket (220a-d) defined by and incorporated in the floating collar (2) and arranged inside the enclosure (3ad).

2. A fish farming system (1) according to claim 1, wherein each air pocket (220a-d) is arranged in an intersection between two sides (2a-d) of the floating collar (2).

3. A fish farming system (1) according to any of claims 1 or 2, comprising a centre structure (222), the centre structure (222) spanning the plurality of enclosures (3a-d).

4. A fish farming system (1) according to the preceding claim, wherein the centre structure (222) comprises an opening into each of the plurality of enclosures (3a-d) for access to the enclosures (3a-d).

5. A fish farming system (1) according to any of the two preceding claims, wherein the air pocket (220a-d) is arranged in the centre structure (222).

6. A fish farming system (1) according to any of the three preceding claims, comprising at least one connecting portion (223) connecting the centre structure (222) to the sides (2a-d).

7. A fish farming system (1) according to any of claims 1-6, wherein the enclosures (3a-d) have:

a rectangular cross-section in the horizontal plane, or

a circular cross-section in the horizontal plane.

8. A fish farming system (1) according to any one of claims 1-7, the fish farming system (1) having a lower buoyancy member (7), an upper buoyancy member (9) and a plurality of columns (8) interconnecting the upper and lower buoyancy members (7,9).

9. A fish farming system (1) according to any one of claims 1-8, wherein the polygonal shaped floating collar (2) is a triangular collar or a rectangular collar.

10. A fish farming system (1) according to any one of claims 1-9, comprising connection members (223) arranged to span a central axis or central point of one or more of the enclosures (3a-d).