NO20190905A1

NO20190905A1 - Fish farm

Info

Publication number: NO20190905A1
Application number: NO20190905A
Authority: NO
Inventors: Leif Salthaug
Original assignee: Fiskevelferd As
Priority date: 2019-07-18
Filing date: 2019-07-18
Publication date: 2021-01-19
Also published as: NO346348B1

Description

FISH FARM

The present invention relates generally to a fish farm, and in particular to a module based offshore fish farm.

Most fish farms are currently located in protected or shielded coastal areas, which has resulted in fewer available fish farming is such protected or shielded areas. This excessive fish farming has also led to major damages to the marine environment.

The growing global demand for aquatic animals, such as fish, crustaceans and mollusc, as a source of food, as well as concerns about harvesting and potential pollution have led to the growth and expansion of aquaculture industry, where new concepts of fish farms have been forced into unprotected or unshielded sea areas.

Traditional open fish farms represent a practical and common aquaculture technology, which technology has made significant progress in recent decades.

Such open fish farms usually comprise one or more flexible floating rings, fishing net, bottom ballasts, mooring systems, and so on. The floating rings are typically subjected to harsh environmental loads, which may lead to fatigue and destruction of the floating rings. Large deformation of the fishing nets in water due to fluid flow is another major problem faced by open fish farms. Furthermore, various organisms that accumulate on fishing nets increase the deformation of the fishing nets, this additional resistance brought by the accumulation affects also the load of the mooring system and may further lead to structural damage of the open fish farming cages.

Installing a fish farm in an unshielded area may have many benefits, including the access to large amounts of space to scale up, large seawater loading capacity, reduction of conflicts with numerous users, reduction of exposure to human sources of pollution and reduction of negative environmental impacts. However, problems and/or disadvantages found in previous studies indicate that conventional open fish farms with flexible floating rings and fishing nets are not suitable for harsh environmental conditions in unshielded sea areas.

Therefore, new and powerful marine fisheries are required to withstand the challenges.

In order to increase the production of seafood, several new fishery concepts with the potential to be used in the open sea have been proposed. Unlike the flexible floating rings widely used in currently operating fish farms, these new concepts make use of rigid support structures to withstand harsh environmental loads.

For instance, a boat-like fish farm has been proposed, where the boat-like fish farm has a single point mooring system working as a weather vane. The fish farm may rotate around a head structure in various environmental directions. Such a system may increase the spread of waste of fish resources and reduce the likelihood of infection. However, the proposed concept faces the following challenges. As the weather vane system allows the system to orient toward water flow and wave directions in most environmental conditions, in this boat-like fish farm downstream net pens are subjected to less water exchange than upstream net pens for the reason that multiple net pens are arranged in a row adjacent to each other. Therefore, levels of dissolved oxygen of the downstream net pens will be lower, than in upstream net pens and the amount of waste increases, which may seriously affect the health of fish. In order to improve water exchange, dynamic positioning systems have been proposed to orient the fish farm at an angle in relation to water flows, but this significantly increases energy consumption as well as operational and maintenance costs.

A rigid semi-submersible fish farm is also proposed and designed, where the concept combines the technology in the field of aquaculture with the offshore oil and gas development technology. The design includes palisade supports, floating body units and a loose mooring system. The fishing nets are pulled tightly and fixed to the supports to avoid deformation in the water flow.

Other have proposed rigid semi-submersible fish farm for unshielded sea areas, which comprises two buoys that are connected by vertical and diagonal brackets. Net pens of the fish farm are fully submerged in the sea to avoid large wave loads near the water surface, and an underwater bag of air is designed to provide air to the fish. It should be noted that this concept uses the traditional gravity net pen, which relies on bottom ballasts to maintain the volume. Such net pens encounter bigger deformation in the high-speed water flow in an unshielded area than in a shielded area. This could threaten the health of fish. In addition, there are also challenges with the use of the underwater bag of air.

In addition to the technology of open fish farms, closed fish farms are also proposed., for instance an oval fish farm. This design mainly considers that living environment is easier to control in closed units. For instance, the possibility of sea lice infection is expected to be smaller than that in the open cages.

Escaping of fish may also be avoided through such a concept. However, because of the complexity of control system and cabin structures used, the cost of such an oval fish farm is expected to be very high. In addition, due to its huge enclosed space and waterline area, the oval structure may suffer from huge environmental loads and internal impacts. As a result, oval structures are difficult to use in unshielded sea areas.

Thus, new configurations of marine fish farms, especially of fish farms in deep seas and high seas, are constantly emerging at present. However, each new fish farm system typically comes with its own problems and/or challenges, such as low sea use, high construction and maintenance costs, and being unfriendly to the environment, to mention a few.

CN 107996483 A relates to a breeding net cage, where the net cage comprises a net cage frame, a top connecting frame, a bottom connecting frame, a net, a balance lifting sinking and floating mechanism and a control mechanism of the balance lifting sinking and floating mechanism. An outer frame and an inner frame of the net cage are formed by the connection between buoyancy risers and horizontal double-connected pipes arranged at the top and bottom, a whole large net cage frame is formed by the outer frame, the inner frame and medium and small bottom frames, a plurality of trapezoidal buoyancy pipe frames are connected with the tops and bottoms of the outer frame and the inner frame in a radiating mode, a circle of multiple sub net cages are arranged within the trapezoidal buoyancy pipe frames, the sub net cages are honeycomb-shaped looking down from the top, and each sub net cage is provided with a balance lifting mechanism. A central net cage is arranged in the center of the whole frame. The sub net cages can be lifted up or lowered down to change depth positions in the water of the sub net cages according to changing conditions of climate and water temperature, living habits of the bred organisms in each of the sub net cages and the like to provide the most suitable living and growing environment for different aquatic organisms.

WO 8704590 A relates to a fish enclosure-construction comprising a rigid, platform-forming construction member which is made of concrete and is adapted to float on or at the surface of the sea. The construction member is provided with a number of cavities for the reception of their respective enclosure pouches. The construction is provided with an upper and a lower, horizontal, rigid construction component which are mutually supported via intermediate pressure-absorbing columns together with a network of tension-absorbing connecting means. A process for making the construction on the sea permits fabrication of the construction components in turn and order individually followed by a mounting of the columns in a supporting abutment between the construction components and securing the components into a coherent construction means of the connecting means.

WO 9009100 A relates to a fish breeding construction comprising a rigid, upper frame-forming construction component and a rigid lower, frame-forming construction component, where the construction components are connected to each other by means of intermediate connection members. In the construction components there are arranged rows of fish pound bags, which are freely flowed through by surrounding sea. The construction components and the connection members are produced in the form of a monolithic frame structure of mutually communicating pipe elements which form a part of a valve-controlled system of ballast-forming or float-forming framework portions.

There is thus a need for alternatives to today's fish fishing farms, or at least supplementary solutions for fish farms.

An object of the present invention is to a provide modular fish farm which from the constructional point of view is simple and robust, and which may be used without the danger of collapse under various climatic conditions, including particularly exposed oceanic regions having heavy wave undulations. Another object is to provide a modular fish farm which is easier to handle at sea. Another object is to provide a modular fish farm which can protect the fish from undesirable environmental incidents, such as lice infestation, algal blooms or the like. Yet another object is to provide a modular fish farm that can be adapted to each location.

These objects are achieved according to the present invention with a modular fish farm as defined in independent claim 1. Further embodiments of the invention are defined in the dependent claims.

The present invention relates to a modular fish farm, where the fish farm comprises at least one adjustable net pen, the adjustable net pen comprising an upper structure and a lower structure, where a net is arranged around an outer circumference of the net pen, a substantially vertical center column further extending through the upper and lower structure of the adjustable net pen, the adjustable net pen being vertically movable relative the center column.

In one embodiment the upper and lower structures of the net pen may have, when seen in a cross-section that forms a plane in which an axis that extends through the center column lies, a form of a truncated cone. However, a person skilled in the art would know that the upper and lower structures of the net pen could be designed to have other forms; the upper structure of the net pen could, for instance, have a flat or plan shape or form, while the lower structure of the net pen could have the form of a truncated cone or the form of a semicircle. It could also be envisaged that both the upper and lower structures of the net pen could have a semicircular form.

According to one aspect the modular fish farm may further comprise at least one frame structure to accommodate a net pen, where the frame structure may comprise an upper ring and a lower ring, where a plurality of beams is arranged around a circumference of the upper ring and lower ring and extending between the upper and lower rings, thereby supporting the upper and lower ring of the frame structure.

In one embodiment the frame structure may be constructed to have an open upper end, while a plurality of girders, beams, struts or the like is connected to the lower ring to form a “closed” bottom in the frame structure. The center column of the net pen may then be supported by the “closed” bottom of the frame structure when a net pen is arranged within the frame structure.

According to one aspect the plurality of girders, beams, struts or the like that are used to form the “closed” bottom in the frame structure may be provided with a plurality of air nozzles, where the air nozzles are used to pump out air or oxygen into the net pen in order to increase the oxygen content in the net pen. The plurality of air nozzles is then connected to one or more pumps through a number of hoses or pipes.

The frame structure may, when arranged in a body of water and seen from above, have a form of a square, a circle or even a polygonal form.

In one embodiment the modular fish farm may also comprise a framework, where the framework is arranged to support the at least one net pen/ the at least one frame structure accommodating the net pen.

Each of the upper structure and lower structure of the net pen may comprise an inner, smaller ring forming the guide for the center column and an outer, larger ring forming the outer periphery of the net pen, where a plurality of spaced apart connecting elements is arranged to extend between the inner, smaller ring and the outer, larger ring. The connecting elements may be rigid, such as beams, girders or the like, or the connecting elements may be more flexible, such as wires, (fibre) ropes, chains or the like. The connecting elements may further be connected to the net in appropriate ways to support and/or reinforce the net in the upper and lower structures of the net pen.

Furthermore, the inner, smaller ring of the upper structure of the net pen may in one embodiment have such a form that air may be entrapped inside the inner, smaller ring. When the net pen is fully immersed in water, where this is done, for instance, in order to avoid salmon lice and/or algal bloom, air may be pumped into the net pen, whereby some of the air will be collected and entrapped inside the inner, smaller ring of the upper structure of the net pen. The fish may then use this entrapped air to fill up their swim bladder/air bladder.

According to one aspect of the fish farm the upper structure of the net pen may be arranged to have a permanent positive uplift or buoyancy while the lower structure of the net pen may be arranged to have a permanent negative buoyancy that is somewhat larger than the positive buoyancy of the upper structure. Such an arrangement of the upper and lower structures will, if a locking system for the net pen fails or is not active, result in that the lower structure of the net pen will sink towards a bottom of the center column, whereafter the lower structure will “rest” on the bottom of the center column when the lower structure reaches the bottom of the center column, while the upper structure will, due to its permanent positive buoyancy, “stretch” the net pen, such that the net pen maintains its form and volume.

However, it may also be envisaged that the upper and lower structures of the net pen could comprise a ballasting and deballasting system, where such a ballasting and deballasting system may be used to arrange the net pen in a specific position, and/or to use the ballasting and deballasting system when the net pen is to be raised or lowered relative the center column. Such a ballasting and deballasting system may also be used to “stretch” the net pen, such that the net pen maintains its form and volume.

The center column and/or frame structure of the fish farm may comprise a locking system to lock the net pen in a specific position relative the center column and/or frame structure, for instance in a normal position of use (where the net pen is not fully immersed in the body of water), in a fully immersed position (in order to avoid salmon lice and/or algal bloom), or in a “drying” position above a surface of the body of water (when the net pen is to be dried and/or washed).

The locking system may, in one embodiment, comprise a number of electromagnets arranged in different planes or levels in or at the center column and/or frame structure, the electromagnets being such arranged that a number of electromagnets may retain or lock the inner, smaller ring and/or the outer, larger ring of the upper structure of the net pen in one position, simultaneously as a number of electromagnets retain or lock the inner, smaller ring and/or the outer, larger ring of the lower structure of the net pen in this position (i.e. a normal position of use, a fully immersed position or a “drying” position).

The electromagnets of the locking system are then connected to a control system.

However, a person skilled in the art will know that the locking system also may comprise hydraulic or mechanical arrangements to obtain the locking of the net pen in a position. As the person skilled in the art will know how these mechanical or mechanical arrangements can be designed, this is not described any further herein.

The upper structure and/or lower structure of the net pen may further comprise a locking arrangement, such that the larger, outer rings of the upper structure and the lower structure may be locked to each other when the net pen is closed together, for instance when the net pen is brought to a “drying” position above the surface of body of water. A crane, winch, hoist may then be used to lift the lower structure of the net pen up towards the upper structure of the net pen, and when the outer, larger rings of the upper structure and lower structure of the net pen are brought close to each other, the outer, larger rings may be locked to each other through the locking arrangement. Thereafter the “closed” net pen is lifted to the “drying” position and is locked in this position through the locking system. A person skilled in the art would know how such a locking arrangement should be arranged, whereby this is not described any further herein.

The center column may, in one embodiment, be provided with a number of openings arranged in a number of levels over a length of the center column, where the number of openings in a level may be used to supply fodder into the net pen, the number of openings in another level may be used to supply air or oxygen to the net pen, the number of openings in yet another level may be used to transport dead fish out from the net pen and the number of openings in yet another level may be used to transport out fish from the net pen when the net pen for some reason is to be emptied, for instance if the fish is to be transported to a slaughter place, if the fish is to be treated or the like.

The number of openings of the center column may then be connected to one or more hose bundles and/or pipes, where these hose bundles and/or pipes extend to an interior of a floating structure, where the interior of the floating structure is provided with a number of rooms, compartments and facilities for storage. The one or more hose bundles and/or pipes will then provide a connection between the center column(s) and the floating structure, such that fodder, air or oxygen may be supplied to the net pen, and that living and dead fish may be transported out from the net pen.

Furthermore, the center column may in one embodiment comprise a lifting arrangement arranged inside or outside the center column, where the lifting arrangement may be used to move the net pen relative the center column. The lifting arrangement may comprise at least one winch, hoist or the like.

The fish farm according to the present invention may, in one embodiment, further comprise a floating structure, where the floating structure may comprise a crane, a number of facilities for storage of, for instance, fish fodder, different pumps, one or more air compressors, delousing unit or the like. The floating structure may also comprise one or more treatment chambers for fish, a control room, one or more tanks for cleaner fish and dead fish and tank for fresh water etc.

The floating structure may also comprise a quay or dock, such that one or more vessels may come alongside the quay or dock.

Furthermore, the fish farm may comprise a device for collecting of feces and/or excess fodder dropping down from the net pen. One device for collecting of feces and/or excess fodder may then be arranged under each net pen, where the device for collecting of feces and/or excess fodder may be connected to the center column, frame structure or framework.

The device for collecting of feces and/or excess fodder may in one embodiment comprise a ring, a number of struts and a net arranged to tapper into a funnel-shaped form. A lowermost part of the device for collecting of feces and/or excess fodder may be connected to a hose of flexible pipe, such that sediments from the net pen could be transported away from the device for collecting of feces and/or excess fodder in order to be treated at a nearby structure.

According to one aspect the fish farm may also include a lighting system, where the lighting system comprises a number of light sources that are at different levels over a length of the center column and/or the frame structure. The light sources may be used to steer, hold and “influence” the fish in specific layers and/or areas of the net pen.

Depending on the wavelength of the light of the light sources, the light sources may be used to “scare away” and/or “attract” the fish in the net pen, to provide better welfare, later maturation, faster growth and greater survival for the fish in the net pen.

Other advantages and features of the invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims, wherein:

Figure 1 shows a perspective view of a first exemplary embodiment of a modular fish farm according to the present invention,

Figure 2 shows a perspective view of an alternative exemplary embodiment of the modular fish farm according to figure 1,

Figure 3 shows a perspective view of another exemplary embodiment of a fish farm according to the present invention,

Figure 4 shows in greater detail a net pen arranged in a frame structure,

Figures 5A-5B show different positions the net pen may be arranged in, where figure 5A shows the net pen arranged in a normal position, figure 5B shows the net pen arranged in a submerged position, and figure 5C shows the net pen in a “drying” position above water, where the net pen is “closed” together,

Figure 6 shows an exemplary floating structure of the fish farm according to the present invention,

Figure 7 shows connection between the floating structure and the net pens,

Figures 8 to 10 show details of the net pen,

Figure 11 shows how the net pen can be maintained in a position within the frame structure,

Figure 12 show in a perspective view another exemplary embodiment of the fish farm according to the present invention, and

Figure 13 shows how the net pen can be transferred from the fish farm to a vessel.

Figure 1 shows in a perspective view of a first exemplary embodiment of a modular fish farm 1 according to the present invention, where the fish farm 1 comprises at least one net pen 2.

The net pen 2 comprises an upper structure 3 and a lower structure 4, where a net is arranged around an outer circumference of the net pen 2 in order to form a “closed” enclosure.

In one embodiment the net that covers the net pen 2 may be in one piece, thereby covering the entire circumference of the net pen 2.

In an alternative embodiment the net may comprise a number of separate pieces, where, for instance, a piece of net 5 may be arranged to cover the upper structure 3 of the net pen 2, another piece of net 6 will be arranged to cover the lower structure 3 4 of the net pen 2, and yet another piece of net 7 will extend between the upper and lower structure 3, 4 and around the outer periphery of the net pen 2 in order to form the “closed” enclosure.

A person skilled in the art would know that the net could be arranged on an outside or an inside of the net pen 2.

Each of the upper structure 3 and lower structure 4 of the net pen 2 comprises an inner, smaller ring 9 forming the guide for a center column 8, and an outer, larger ring 10 forming the outer periphery of the net pen 2. Furthermore, a plurality of spaced apart connecting elements 50, such as wire, fibre ropes, chains or the like, are arranged to extend between the inner, smaller ring 9 and the outer, larger ring 10, in order to support and/or to stiffen the net 5, 6 of the upper and lower structure 3, 4 of the net pen 2. However, a person skilled in the art would know that the connecting elements 50 could be of a more rigid type, such as beams, girders or the like.

The upper structure 3 and the lower structure 4 of the net pen 2 will, when seen in a cross-section that forms a plane in which an axis A that extends through the center column 8 lies, has a form of a truncated cone.

In one embodiment the upper structure 3 of the net pen 2 may be arranged in such a way that the inner, smaller ring 9 of the upper structure 3 of the net pen 2 will be closest to a surface of a body of water, while the lower structure 4 of the net pen 2 may be arranged in such a way that the outer, larger ring 10 of the lower structure 4 of the net pen 2 will be closest to the surface of the body of water.

Furthermore, the upper structure 3 of the net pen 2, with the weight of the net, is arranged to have a permanent positive uplift or buoyancy, while the lower structure 4 of the net pen 2, with the weight of the net, is arranged to have a permanent negative buoyancy that is somewhat larger than the positive buoyancy of the upper structure 3 of the net pen 2.

The center column 8 will have a positive uplift or buoyancy.

A device C for collecting of feces and/or excess fodder is arranged under the net pen 2, where the device C for collecting of feces and/or excess fodder in appropriate ways is connected to a lower end of the center column 8.

The device C for collecting of feces and/or excess fodder comprises a ring 11A, a number of struts 11B and a net 12 arranged to taper towards a bottom of the body of water, thereby having a funnel-shaped form. Furthermore, the device C for collecting of feces and/or excess fodder is, at its lowermost part, connected to a hose or flexible pipe 13, such that the sediments could be transported away from the device C for collecting of feces and/or excess fodder in order to be treated at a nearby structure (not shown).

The ring 11 of the device C for collecting of feces and/or excess fodder is supported and stiffened through pipes or struts 11C.

The center column 8, see also figures 8-10, is provided with one or more openings 23, 24, 25, 26 arranged in a number of levels over a length of the center column 8 and around a circumference of the center column 8, where the one or more openings 23 arranged in a first level may be used to deliver out fodder to the net pen 2. The one or more openings 24 arranged in a second level near a lower part of the center column 8 may be used to transport away dead fish collected in a lowermost part of the net pen 2. The one or more openings 25 arranged in a third layer may be used to supply or deliver air or oxygen to the net pen 2. The one or more opening 26 arranged in a fourth layer may be used to empty the fish from the net pen 2, for instance when the fish is to be transported to a slaughter place or another location, if the fish for some reason must be treated or the like.

The one or more openings 23, 24, 25, 26 are then connected to one or more hoses (not shown), where these hoses further are connected to appropriate equipment arranged in a nearby (floating) structure (not shown).

Each net pen 2 is movable relative the center column, i.e. along the axis A extending through the center column 8, whereby each center column 8 is provided with one or more winches or hoists (not shown) inside the center column 8. The one or more winches (not shown) may be used when the net pen(s) 2 is/are to be positioned as described according to figures 5A-5C or when the net pen(s) 2 of the fish farm 1 is/are to be emptied.

One or more mooring lines (not shown) is used to anchor the net pen 2 to a bottom of the mass of water.

Figure 2 shows an alternative exemplary embodiment of the fish farm 1 according to figure 1, where the fish farm 1 in this embodiment comprises five net pens 2 that are connected to a floating structure 14 through a framework 51.

An interior of the floating structure 14 is divided into a number of rooms, compartments or facilities for storage, of, for instance, fish fodder, different pumps and/or pump systems, one or more air compressors, treatment chambers for fish, one or more tanks for cleaner fish and dead fish, a control room, one or more tanks for fresh water etc.

The floating structure 14 may further be provided with equipment, components and/or elements needed for the running and/or operation of the fish farm 1 throughout the lifetime of the fish farm and under all operating conditions, where this, for instance, may be hoses, sludge handling system, oxygenation system for fish or the like.

The framework 51 according to this embodiment of the fish farm 1 comprises a number of pipes, where a longitudinal pipe will support three transverse pipes. Two of the transverse pipes will, through each of their ends, be connected to the center column 8 of a net pen 2, while the last transverse pipe will, through one of its end, be connected to the center column 8 of the net pen 2 and through an opposite end be connected to the floating structure 14.

A device C for collecting of feces and/or excess fodder is also connected to each end of the transverse pipes of the framework 51.

As the net pens 2 in this embodiment are designed or fabricated in the same manner as the net pen 2 described through the first embodiment, reference is made to the description of the net pen 2 according to figure 1.

The device C for collecting of feces and/or excess fodder is also described through the first embodiment, whereby reference is made to the description of the device C for collecting of feces and/or excess fodder according to figure 1.

The center column 8 is, also in this embodiment, provided with one or more openings 23, 24, 25, 26 arranged in a number of levels over a length of the center column 8 and around the circumference of the center column 8, whereby reference is made to the description of the center column 8 according to figures 1 and 8-10.

Figure 3 shows another exemplary embodiment of a modular fish farm 1 according to the present invention, where the fish farm 1 in this embodiment in addition comprises a frame structure 15 for the net pen 2.

The fish farm 1 according to this embodiment comprises three net pens 2, each net pen 2 being arranged in a dedicated frame structure 15, where the frame structures 15 and the net pens 2 arranged in the frame structures 15 are arranged around a floating structure 14.

Although not shown in figure 3, the fish farm 1 according to this embodiment also comprises a device C for collecting of feces and/or excess fodder, whereby reference is made to the description of the device C for collecting of feces and/or excess fodder according to figure 1.

Each net pen 2 is furthermore connected to the floating structure 14 of the fish farm 1 through one or more hose bundles and/or pipes 22, where the one or more hose bundles and/or pipes 22 extend from an inner interior of the floating structure 14 and to each center column 8 of the net pen 2, where the one or more hose bundles and/or pipes 22 are connected to dedicated one or more openings 23, 24, 25, 26 provided in the center column 8.

One hose or hose bundle (or pipe) 22 may then form a connection between a compartment for storage of fodder inside the floating structure 14, a feeding machine (not shown) and one or more openings 23 provided in each center column 8 in order to deliver out fodder in each net pen 2.

Similarly, one or more hose bundles and/or pipes 22 form a connection between one or more openings 24, 25, 26 provided in each center column 8 and appropriate equipment arranged inside the floating structure 14 in order to transport away dead fish from the net pen 2, to supply or deliver air or oxygen to the net pen 2, and to empty the fish from the net pen 2, for instance, when the fish is to be transported to a slaughter place or another location, if the fish for some reason must be treated etc.

The frame structure 15 comprises an upper ring 17 and a lower ring 18, where a plurality of beams 19 are arranged around a circumference of the upper and lower rings 17, 18, the beams 19 further extending between the upper and lower rings 17, 18.

The frame structure 15 will have an open upper end, while the lower ring 18 is provided with girders 20 to form a “closed” bottom in the frame structure 15. The girders 20 will also support the center column 8 of the net pen 2, as the center column 8 in appropriate ways is connected to the girders 20 of the frame structure 15.

In this embodiment the upper and lower rings 17, 18 are shown to have a polygonal form, but it could also be envisaged that the upper and lower rings 17, 18 could have other forms, for instance a circular form, a square form or the like, as long as the shape of the frame structure 15 support the net pen 2 arranged inside the frame structure 15.

A crane 21 is furthermore arranged centrally on the floating structure 14, where the crane 20, for instance, is used to lift and transport the net pens 2 from the fish farm 1 and to a vessel (not shown) when the net pens 2 are to be replaced, or when the net pen(s) 2 is/are to be positioned relative the center column 8 as described according to figures 5A-5C, or when the net pen(s) of the fish farm 1 is/are to be emptied.

Figure 4 shows in greater detail the net pen 2 according to figure 3 arranged in the frame structure 15.

The girders 20 that form the “closed” bottom in the frame structure 15 may be provided with a plurality of air nozzles (not shown), where these air nozzles may be used to pump out air or oxygen into the net pen 2 in order to increase the oxygen content in the net pen 2. The plurality of air nozzles is then connected to one or more pumps through a number of hoses or pipes.

Figures 5A-5C show how the net pen 2 can be arranged in different positions inside the frame structure 15, where figure 5A show the net pen 2 arranged in a normal position of use, i.e. in a position where the net pen 2 is not fully immersed in the body of water. Figure 5B shows the net pen 2 in an immersed position, where the net pen 2 can be lowered to this position in order to avoid salmon lice and/or algal bloom. Figure 5C shows the net pen 2 in a “drying” position, where the net pen 2 has been lifted up by the crane 21 to this position, whereafter the net pen 2 is “closed” together.

The inner, smaller ring 9 of the upper structure 3 of the net pen 2 is designed in such a way that it will “collect” or entrap air on an inside of the inner, smaller ring 9. When the net pen 2 is lowered to the fully immersed position, as shown in figure 5B, air is pumped into the net pen 2 through the one or more openings 25 provided in the center column 8 and/or the plurality of air nozzles provided in the girders 20 of the frame structure 15, and some of the air will be collected and entrapped inside the inner, smaller ring 9 of the upper structure 3. The fish will then be able to swim up to the entrapped air to fill up the swim bladder.

The net pen 2 is kept in the different positions through a locking system 27, which is described in accordance with figure 11, where the locking system 27 comprises a number of electromagnets 27. If the locking system 27 for some reasons fails, or the locking system 27 is not active, the net pen 2 will sink to the immersed position, as the upper structure 3 of the net pen 2 is arranged to have a permanent positive buoyancy, while the lower structure 4 of the net pen 2 is arranged to have a permanent negative buoyancy that is somewhat larger than the positive buoyancy of the upper structure 3 of the net pen 2. A bottom of the center column 8 will then prevent the net pen 2 to sink any further, while the upper structure 3 of the net pen 2 will, due to its permanent positive buoyancy, stretch the net pen 2, such that the net pen 2 maintains its form and volume.

Figure 6 shows an exemplary embodiment of a floating structure 14 of the fish farm according to the present invention, where the floating structure 14 comprises a crane 21.

The crane 21 is used to lift the net pens 2, handling of goods, equipment etc. from a vessel (not shown) and to the fish farm 1 and vice versa.

An interior of the floating structure 14 is divided into a number of rooms, compartments or facilities for storage of, for instance, fish fodder, different pumps and/or pump systems, one or more air compressors, treatment chambers for fish, one or more tanks for cleaner fish and dead fish, a control room, one or more tanks for fresh water etc.

The floating structure 14 may further be provided with equipment, components and/or elements needed for the running and/or operation of the fish farm throughout the lifetime of the fish farm and under all operating conditions, where this, for instance, may be hoses, sludge handling system, oxygenation system for fish or the like.

Figure 7 shows how three net pens 2 are arranged around the floating structure 14 according to figure 6, where it can be seen that each net pen 2 is connected to the floating structure 14 of the fish farm 1 through one or more hose bundles and/or pipes 22, where the hose bundles and/or pipes 22 extend from an inner or interior of the floating structure 14 and to the center column 8 of the net pen 2, where the one or more hose bundles and/or pipes 22 is/are connected to dedicated one or more openings 23, 24, 25, 26 provided in the center column 8.

The center column 8 is provided with a plurality of openings arranged in a number of levels over the center columns 8 length, see also figures 8 and 9, where one or more openings 23 arranged in a first level may be used to deliver out the fodder that is transported from the floating structure 14 and to the center column 8, in order to feed the fish inside the net pen 2. A hose will then form a connection between the one or more openings 23, a feeding machine for fish and one or more compartments for storage of fodder inside the center column 8, whereby the feeding machine for fish will feed the fish inside the net pen 2 by throwing the fodder out through the one or more openings 23.

The center column 8 is also provided with one or more openings 24 around its circumference, arranged in a second level, where this or these openings 24 will collect dead fish in the net pen 2. The opening or openings 24 are then connected to one or more hoses (not shown), where this or these hoses will be lead to a collection tank (not shown) inside the floating structure 14. These openings 24 are arranged in a lower part of the center column 8.

Although not shown in figure 7, the fish farm 1 will also comprise a device C for collecting of feces and/or excess fodder, where one device C for collecting of feces and/or excess fodder is arranged under each net pen 2. The device C for collecting of feces and/or excess fodder is connected to the center column 8 or to the frame structure 15.

The device C for collecting of feces and/or excess fodder is described in accordance with figure 1.

As seen from figure 9, the center column 8 is furthermore provided with one or more openings 25 around its circumference, arranged in a third level, where this or these openings 25 serve the purpose to supply or deliver fresh air to the net pen 2. A hose (not shown) is then connected to each opening 25 and extends into the floating structure 14, to a pumping room (not shown) arranged inside the floating structure 14.

The center column 14 is also provided with a plurality of openings 26 arranged in a fourth layer, see figure 10, where these openings 26 are provided around the circumference of the center column 8. These openings 26 will be used when the net pen 2 or net pens 2 of the fish farm 1 for some reason is/are to be emptied, for instance when the fish is to be transported from the fish farm 1 and to a slaughter place, if the fish are to be transported to another location, if the fish for some reason must be treated in the floating structure 14/ a vessel (not shown) or the like. These openings 26 are located near the surface of the body of water.

The crane 21 will then be used to lift the net pen 2 slowly up from the frame structure 15, whereby the form of the lower structure 4 of the net pen 2 will result in that the fish will be concentrated or compressed in the lowermost areas of the lower structure 4. Fish inside the net pen 2 will then be pumped out though the plurality of openings 26 and to one or more chambers provided in the interior of the floating structure 14.

Alternatively, if the fish farm 1 does not comprise a crane, see for instance embodiments described in accordance with figures 1 and 2, each center column 8 may be provided with one or more winches or hoists (not shown) inside the center column 8, where these one or more winches or hoists is/are used to lift or lower the net pens 2 relative the center column 8, for instance when the net pens 2 are to be positioned as described according to figures 5A-5C or when the net pens 2 of the fish farm 1 is/are to be emptied.

Figure 11 shows how a net pen 2 may be kept in one of the three positions inside the frame structure 15, where the locking system 27 comprises a number of electromagnets 27 arranged on each beam 19 of the frame structure 15 and on the center column 8. Each beam 19 will then have two electromagnets 27 to be able to retain or “lock” the net pen 2 in a normal position of use (one electromagnet to hold the outer, larger ring 10 of the upper structure 3 and one electromagnet to hold the outer, larger ring 10 of the lower structure 4); two electromagnets 27 to be able to retain or “lock” the net pen 2 in a submerged position (one electromagnet to hold the outer, larger ring 10 of the upper structure 3 and one electromagnet to hold the outer, larger ring 10 of the lower structure 4); and one electromagnet 27 to retain or “lock” the net pen 2 in a “drying” position above the surface of the body of water, where the net pen 2 in this position is “closed” together (i.e. the upper and lower structure 3, 4 of the net pen 2 are moved towards each other, and the outer, larger rings 10 of the upper and lower structure 3, 4 of the net pen 2 are thereafter, through appropriate locking arrangement (not shown), locked to each other.

The center column 8 will also be provided with three pairs of electromagnets 27, where the pairs are arranged in three different levels. The electromagnets 27 on the center column 8 will only retain or lock the inner, smaller ring 9 of the upper structure 3 of the net pen 2.

Figure 12 show yet another embodiment of the fish farm 1 according to the present invention, where the fish farm 1 comprises three frame structures 15, a net pen 2 being arranged in each frame structure 15, and a floating structure 14.

In this embodiment the floating structure 14 is provided in the form of a “H”, where this form will allow a vessel (not shown) to come alongside the quay of the floating structure 14 also between two adjacent frame structures 15.

Figure 13 shows how the crane 21 can be used to lift up the net pen 2 from the frame structure 15, where the net pen 2, before it is lifted up from the frame structure 15, is closed together.

The invention has now been explained with several non-limiting exemplary embodiments. One skilled in the art will appreciate that a variety of variations and modifications can be made to the fish farm as described within the scope of the invention as defined in the appended claims.

Claims

1. A fish farm (1) comprising at least one adjustable net pen (2), characterized in that the adjustable net pen (2) comprises an upper structure (3) and a lower structure (4), a net arranged around an outer circumference of the net pen (2), a substantially vertical center column (8) further extending through the upper structure (3) and lower structure (4) of the adjustable net pen (2), the adjustable net pen (2) being vertically movable relative the center column (8).

2. A fish farm (1) according to claim 1,

characterized in that each of the upper structure (3) and lower structure (4), when seen in a cross-section perpendicular to an axis extending through the center column (8), has form of a truncated cone.

3. A fish farm (1) according to any of the preceding claims,

characterized in that each of the upper structure (3) and lower structure (4) comprises an inner, smaller ring (9) forming the guide for the center column (8) and an outer, larger ring (10) forming the outer periphery of the net pen (2), a plurality of spaced apart connecting elements (50) extending between the inner, smaller ring (9) and the outer, larger ring (10).

4. A fish farm (1) according to any of the preceding claims,

characterized in that the upper structure (3) of the net pen (2) has a permanent positive buoyancy, while the lower structure (4) of the net pen (2) has a permanent negative buoyancy somewhat larger than the permanent positive buoyancy of the upper structure (3) of the net pen (2).

5. A fish farm (1) according to claim 1,

characterized in that the center column (8) is provided with a plurality of openings (23, 24, 25, 26) arranged in a number of levels over a length of the center column (8).

6. A fish farm (1) according to claim 1 or 5,

characterized in that the center column (8) comprises at least one winch or hoist (not shown) arranged inside the center column (8), the at least one winch or hoist being used to lift or lower the net pen (2).

7. A fish farm (1) according to any of the preceding claims,

characterized in that the fish farm (1) further comprises at least one frame structure (15) to accommodate a net pen (2), the frame structure (15) comprising an upper ring (17) and a lower ring (18), where a plurality of beams (19) are arranged around a circumference of the upper ring (17) and lower ring (18) and extending between the upper and lower ring (17, 18).

8. A fish farm (1) according to claim 4,

characterized in that a plurality of girders (20) are connected to the lower ring (18) of the frame structure (15) to form a “closed end” in the frame structure (15).

9. A fish farm (1) according to any of the preceding claims,

characterized in that the fish farm (1) further comprises a framework (51) supporting the at least one net pen (2).

10. A fish farm (1) according to any of the preceding claims, characterized in that center column (8) and/or frame structure (15) comprises a locking system (27) to lock the net pen (2) in a position relative the center column (8) and frame structure (15).

11. A fish farm (1) according to claim 8,

characterized in that the locking system (27) is elected from a group consisting of electromagnets, hydraulic fastening means and mechanical fastening means.

12. A fish farm (1) according to any one of the preceding claims, characterized in that the fish farm (1) further comprises a floating structure (14), the floating structure comprising a crane (21).

13. A fish farm (1) according to claim 7,

characterized in that the floating structure (14) further comprises a quay.

14. A fish farm (1) according to any of the preceding claims,

characterized in that the fish farm (1) further comprises a device (C) for collecting of feces and/or excess fodder, the device (C) for collecting of feces and/or excess fodder being connected to the center column (8) or frame structure (15).

15. A fish farm (1) according to claim 11,

characterized in that the center column (8) is provided with six electromagnets (27) and/or each beam (19) is provided with five electromagnets (27).

16. A fish farm (1) according to one or more of the preceding claims 7-8, characterized in that an interior of the floating structure (14) is divided into a number of rooms, compartments and facilities for storage of fish fodder, different pumps and/or pump systems, one or more air compressors, treatment chamber for fish, one or more tanks for cleaner fish and dead fish, a control room, a delousing unit and one or more tanks for fresh water.

17. A fish farm (1) according to any of the preceding claims,

characterized in that the inner, smaller ring (9) of the upper structure (3) of the net pen (2) comprises a “pocket” for collection and entrapment of air.