Crowding device for fish farms

Abstract

A device and method are described for crowding and discharging live marine organisms from a tank, comprising a horizontally arranged perforated crowding grid, where the crowding grid is designed to be lifted from an inactive position at the bottom of the tank and vertically upward to crowd the liquid and marine organisms out of the tank.

Description

[0001] CROWDING DEVICE FOR FISH FARMS

[0002] Field of the Invention

[0003] The present invention relates to a device and method for crowding and moving marine organisms, such as fish, in a liquid in a tank. Preferably, the tank is circular, such as an aquaculture tank for marine organisms, but other shapes such as rectangular, square, or hexagonal can also occur.

[0004] Background of the Invention

[0005] Given the environmental challenges faced today with the farming of marine species in open sea pens, more and more production must take place in closed tanks. The need for increased production and returns means that the tanks are getting larger and larger, and to maximize these, fish must be moved from one tank to another as the fish or marine organism grows. The water, i.e., the liquid in which the marine organism resides, is valuable, and it is not feasible to crowd and move fish by emptying such large tanks. The water must therefore be transferred together with the fish to a new tank while preferably maintaining the liquid levels in the tanks. Moving fish is becoming an increasingly important part of the operational form in a fish farming facility as the facilities become larger and larger, as one wants to maximize the tank volumes for production, thus having as much biomass as possible in the tank at any given time.

[0006] Moving marine organisms, such as fish, can be divided into two steps: first, the fish are crowded together to a suitable location in the tank, and then the fish are moved or transferred to another tank. The crowding itself is a critical operation, as it triggers stress reactions in the fish. This leads to increased oxygen consumption and the release of carbon dioxide. This is a significant strain on the fish. The fish then seek downward in the tank. This is an instinct that most fish species have. It is therefore important to consider this in the design of mechanisms for crowding and leading the fish out of the tank.

[0007] Description of Prior Art

[0008] Various solutions exist today for crowding fish, where the fish are guided into a piping system that takes them out of the tank. In sea pens, crowding nets are often used to gather the fish in bags where they are sucked up and into a fish pump. This type of crowding system causes a lot of stress on the fish and leads to high mortality. In closed tanks, different methods are used, ranging from draining the water to various forms of crowding boards that press the fish into an increasingly smaller sector from which they are pumped out. The best solutions then crowd the fish down to the bottom and suck them out through a hole in the tank wall. A typical example of this is shown in patent application PCT / N02021 / 050275 and in NO324024. MMC Tendos AS describes in NO324024 a solution for crowding fish in cylindrical tanks, primarily intended for use in wellboats that transport fish. Issues related to flow conditions and sedimentation of particles in the tank in such wellboats are not as relevant for the present invention. The solution is based on elevating profiles mounted on or near the bottom of the tank, and a grid shaped approximately the same as the tank is lowered towards these elevating profiles. When the grid reaches the height of these elevating profiles, one of the elevating profiles is rotated around the center of the tank, pressing the fish into a small sector. The opening out of the tank is in the tank wall in this sector, and the fish are finally pressed out through the opening in the tank wall for transfer to a new container.

[0009] This solution has several disadvantages, especially in tanks where the fish are to stay for a longer period and where they are also to be fed. The elevating profiles at the bottom will affect the flow pattern in the tank, and sedimentation of fish waste and feed residues will occur around these profiles. This is a major disadvantage in tanks where large quantities of fish are to be produced.

[0010] At the same time, it is a disadvantage to take the fish out through a hole in the tank wall at the bottom, as this is often embedded in the ground, making it difficult to clean, thus easily becoming a trap for stagnant water that readily develops hydrogen sulfide, which is highly toxic to the fish.

[0011] Patent application PCT / N02023 / 000002 describes a solution where a crowding grid is moved from an inactive position at the bottom of the tank, and this vertical movement upward in the tank crowds the fish located above the crowding grid.

[0012] The applicant's patent application N020240046 describes a solution where a framework with a number of panels is lowered into the tank. The lowering is done so that at least one of the panels is not arranged in the framework, i.e. , so that a passage is formed in the framework, allowing the fish to swim through. When the framework is to be pushed upward, to crowd the fish upward in the tank, all the panels cover the framework completely, so that only water, and not fish, can pass through the framework.

[0013] Objects of the Invention

[0014] It is an object of the present invention to provide an improvement or alternative solution to the solution shown in N020240046.

[0015] The object of the invention is to provide a system (a device and method) for moving a crowding grid from a position above the liquid level in the tank down to the bottom of the tank, so that the crowding grid is positioned under the fish that reside in the tank. Furthermore, it is an object of the invention to perform this in a gentle manner, preferably more gently than with known methods and devices. It is an object to take into account the natural reaction pattern of the fish in that they seek downward when frightened. Another object of the invention is that there are no penetrations in the tank wall below the water level.

[0016] The applicant has various patents and patent applications related to closed tank solutions, where, among other things, the tank's importance of having clean smooth internal surfaces has been emphasized, i.e., without objects that disturb the flow pattern and create particle sedimentation. A clean cylindrical tank without installations on the internal surfaces that provide good tank hydraulics is therefore of great importance for efficient farming in closed tanks. Likewise, the device that crowds the fish must be reliable and easy to handle, as crowding and moving fish is something that happens frequently. The solution should also be operable while the water circulates in the tank. The water speed in the tank can typically be 0.5 m / s. This can exert large forces on objects that are to crowd the fish.

[0017] Summary of the Invention

[0018] The solution for which a patent is sought consists of a horizontally arranged crowding grid, in the form of a perforated cover that can move up and down around the central column in an aquaculture tank. The grid must be positioned in an inactive position at the bottom of the tank, and with the present invention, this can be done even when there are fish in the tank. The crowding grid is perforated so that water flows through it and is sucked out under the grid and into the central column. This will ensure that there is no sedimentation of particles under the grid. Fish that die will lie on top of the grid and periodically be sucked towards the central column, into it, and out of the facility.

[0019] When the fish are to be crowded and moved out of the tank, the crowding grid is moved from its inactive position at the bottom of the tank and vertically upwards. A suction arrangement can be lowered into the tank and positioned just above the crowding grid. The fish are crowded to this position and transferred via the suction arrangement out of the tank (transferred to a new tank). Preferably, the suction arrangement is connected to a siphon that leads the fish out of the tank.

[0020] The principle underlying the present invention is that the crowding grid comprises two or more crowding grid units, each of which comprises sections that are open and sections equipped with a grid. When two or more such crowding grid units are rotated relative to each other, a framework can be established in which all sections have a grid, i.e., so that fish cannot swim through the framework, and this configuration is used when the crowding grid units are moved upwards in the tank, crowding the fish to a new location. Furthermore, these crowding grid units can also be set so that at least one open section lies above each other, i.e., so that the fish can move through the crowding grid units, and this configuration is used when the crowding grid units are lowered into the tank to an inactive position. A framework with crowding grid units can be lowered into the tank even when there are fish in the tank because the fish can move through the open sections in the crowding grid units.

[0021] In a first aspect, the present invention relates to a device for crowding and moving live marine organisms from a tank, where the device comprises one or more horizontally arranged perforated crowding grids, where the crowding grids are arranged to be raised from an inactive position at the bottom of the tank and vertically upwards for crowding the liquid and the marine organisms out of the tank, characterized in that the crowding grids comprise panels or crowding grid units, where the panels are open or comprise a grid, where the crowding grids can be moved from a storage position above the liquid level in the tank to the lower inactive position, where the crowding grids as they are lowered in the tank have at least one open panel / unit so that the marine organisms can move through the crowding grids, and where the panels / units are repositioned in the lower position so that the crowding grids do not comprise any open sections and thus crowd the marine organisms upwards in the tank as the crowding grids are raised upwards in the tank.

[0022] In one embodiment, a crowding grid comprises two or more crowding grid units arranged to be able to rotate relative to each other, and where these crowding grid units comprise a framework (16a) and a number of panels that are open or formed by a grid, where at least one of the panels in each crowding grid unit is open, so that the crowding grid can be moved from a storage position above the liquid level in the tank to the lower inactive position as two panels with openings are arranged above each other so that the marine organisms can move through the crowding grid, and that when the crowding grid is in the lower inactive position, the crowding grid units are rotated relative to each other so that a perforated crowding grid is established that extends between the wall sections of the tank.

[0023] In one embodiment, a flexible element is arranged between the tank walls and the outer circumference of the perforated crowding grid, and between the crowding grid and the central column, to seal the distance between the tank wall and the crowding grid.

[0024] In one embodiment, the mentioned flexible element is a flexible hose arranged to be pressurized with water to seal between the frame and the tank wall / central column.

[0025] In one embodiment, the crowding grid is raised in the tank while a constant water flow is introduced into and up into the suction arrangement. In one embodiment, the device comprises a suction arrangement for removing liquid and marine organisms, where the suction arrangement is arranged just above the horizontally perforated crowding grid.

[0026] In one embodiment, the crowding grid is moved vertically up and down in the tank, where the crowding grid is attached to vertical guides along the central column and tank wall.

[0027] In one embodiment, the framework and the panels are each attached with ropes, cables, or wires to an element arranged above the tank.

[0028] In one embodiment, the assembly of the crowding grid has a channel in the center, arranged so that the fish are crowded towards this channel as the crowding grid is moved upwards.

[0029] In one embodiment, the channel of the crowding grid comprises at least one recess.

[0030] In one embodiment, the suction arrangement is arranged in the mentioned recess.

[0031] In one embodiment, the suction arrangement is arranged in the mentioned channel.

[0032] In one embodiment, the framework is constructed as a framework with an inner and outer ring with soft flexible lamellae, preferably made of a plastic material, against the tank wall and central column.

[0033] In one embodiment, the assembly of the crowding grid is designed so that the center of the crowding grid and the suction arrangement are arranged vertically lower than the outer edge of the crowding grid.

[0034] In one embodiment, the panels have a grid structure made of net, grid, or grille material with openings adapted to the size of the marine organisms in the tank, so that they do not pass through the openings in the crowding grid (16) as it has no open sections arranged above each other, but that the liquid flows freely through the crowding grid.

[0035] In one embodiment, the suction arrangement is connected to a siphon that lifts the marine organisms out of the tank through a flexible conduit.

[0036] In one embodiment, the stress level and position of the marine organisms are monitored, and this information is used to control the raising of the horizontally assembled crowding grid.

[0037] In one embodiment, visual and acoustic methods, such as camera, hydrophone, and / or radar, are used to monitor the stress level and position of the marine organisms.

[0038] A preferred embodiment of the invention in the first aspect is indicated in claim 19 and relates to a device in accordance with claim 1 , characterized in that a crowding grid comprises a framework and a number of panels so that the crowding grid can be moved from a storage position above the liquid level in the tank to the lower inactive position by first lowering the framework into the tank, and then lowering the panels and positioning them on the framework to establish a perforated crowding grid that extends between the tank wall sections.

[0039] In one embodiment of the solution indicated in claim 19, a flexible element is arranged between the tank walls and the outer circumference of the perforated crowding grid, and between the crowding grid and the central column to seal the distance between the tank wall and the crowding grid.

[0040] In one embodiment of the solution indicated in claim 19, the mentioned flexible element is a flexible hose arranged to be pressurized with water to seal between the frame and the tank wall / central column.

[0041] In one embodiment of the solution indicated in claim 19, the crowding grid is raised in the tank while a constant water flow is introduced into and up into the suction arrangement.

[0042] In one embodiment of the solution indicated in claim 19, the device comprises a suction arrangement for removing liquid and marine organisms, where the suction arrangement is arranged centrally just above the horizontally perforated crowding grid.

[0043] In one embodiment of the solution indicated in claim 19, the crowding grid is moved vertically up and down in the tank, where the crowding grid is movably attached to vertical guides along the central column and tank wall.

[0044] In one embodiment of the solution indicated in claim 19, the framework and the panels are each attached with ropes, cables, or wires to an element arranged above the tank.

[0045] In one embodiment of the solution indicated in claim 19, the assembly of the crowding grid has a channel in the center, arranged so that fish are crowded towards this channel as the crowding grid is moved upwards.

[0046] In one embodiment of the solution indicated in claim 19, the channel of the crowding grid comprises at least one recess.

[0047] In one embodiment of the solution indicated in claim 19, the suction arrangement is arranged in the mentioned recess.

[0048] In one embodiment of the solution indicated in claim 19, the suction arrangement is arranged in the mentioned channel. In one embodiment of the solution indicated in claim 19, the framework is constructed as a framework with an inner and outer ring with soft flexible plastic-like lamellae against the tank wall and central column.

[0049] In one embodiment of the solution indicated in claim 19, the assembly of the crowding grid is designed so that the center of the crowding grid and the suction arrangement are arranged vertically lower than the outer edge of the crowding grid.

[0050] In one embodiment of the solution indicated in claim 19, the panels have a grid structure made of net, grid, or grille material with openings adapted to the size of the marine organisms in the tank, so that they do not pass through the openings in the crowding grid, but the liquid flows freely through the crowding grid.

[0051] In one embodiment of the solution indicated in claim 19, the suction arrangement is connected to a siphon that lifts the marine organisms out of the tank through a flexible conduit.

[0052] In one embodiment of the solution indicated in claim 19, the stress level and position of the marine organisms are monitored, and this information is used to control the raising of the horizontally assembled crowding grid (16).

[0053] In one embodiment, visual and acoustic methods, such as camera, hydrophone, and / or radar, are used to monitor the stress level and position of the marine organisms.

[0054] In one embodiment, the device comprises only one crowding frame (for example, the upper one shown in the figures) with a battery of panels lying as in a magazine above each other, and the upper frame rotates and pulls out one element at a time from the "magazine" until the entire circumference of the crowding grid is covered.

[0055] In one embodiment, the device comprises a double crowding frame (for example, the upper one shown in the figures) with one or more cone-shaped rollers made of net material that are pulled out by rotating the two crowding frames relative to each other until the entire circumference of the crowding grid is covered with the net.

[0056] In a second aspect, the present invention relates to a method for crowding marine organisms in a tank, characterized in that a horizontally arranged crowding grid is moved from an inactive position at the bottom of the tank upwards in the water column to crowd the fish to the upper level in the tank, characterized in that the crowding grid can be moved from a storage position above the liquid level to the inactive position at the bottom of the tank as the crowding grid is an assembly of two crowding grid elements, each with a number of open panels and a number of grid panels, and that the crowding grid elements can be rotated relative to each other so that the crowding grid elements together are moved down into the tank to the inactive position with two open panels arranged above each other, where the two crowding grid elements are rotated relative to each other in the inactive position, and establish a crowding grid with a grid in all panels, where the marine organisms are moved out of the tank as they seek towards the center of the crowding grid in the upper part of the tank as the crowding grid is moved upwards in the tank.

[0057] In one embodiment, a horizontally arranged crowding grid is moved from an inactive position at the bottom of the tank upwards in the water column to crowd the fish to the upper level in the tank, characterized in that the crowding grid can be moved from a storage position above the liquid level to the inactive position at the bottom of the tank as the crowding grid is an assembly of a frame and a number of panels that are each moved down into the tank to the inactive position, where the marine organisms are moved out of the tank as they seek towards the center of the crowding grid in the upper part of the tank as the crowding grid is moved upwards in the tank.

[0058] In one embodiment, a suction arrangement is located just above the crowding grid, arranged to suck water and marine organisms out of the tank.

[0059] In one embodiment, the crowding grid is moved from an inactive low position in the tank and upwards in the tank to crowd the marine organisms towards the center and to a location just above the crowding grid.

[0060] In one embodiment, the inner edge section of the crowding grid is equipped with a channel, and the fish are led towards this channel during crowding, as the crowding grid moves upwards.

[0061] In one embodiment, the mentioned channel is equipped with at least one recess so that the fish are led into this recess during crowding, and the suction arrangement is positioned in this recess.

[0062] In one embodiment, one or more panels are designed with a recess of net material so that the fish seek down into this during crowding and the suction arrangement is positioned in this recess.

[0063] Description of Figures

[0064] Preferred embodiments of the invention will be described in more detail below with reference to the accompanying figures, where: Figure 1 schematically shows a tank for rearing marine organisms where a framework is arranged in an upper position. The framework (and then the panels) must be lowered into the tank, and this must be done while there are marine organisms (fish) in the tank.

[0065] Figure 2 schematically shows the same tank as in Figure 1 , but where the framework has moved to a lower (bottom of the tank) inactive position. The fish are in the tank above the lowered framework.

[0066] Figure 3 schematically shows a framework. This, along with the panels, constitutes one part of a crowding grid. Preferably, an outer ring is arranged to match the inner profile of the tank (shown here as circular).

[0067] Figure 4a shows how a set of panels is arranged at the top of the tank, ready to be lowered towards the framework that can be seen at the bottom of the tank. In this embodiment, three of the panels are shown as mesh / net / grid, while one panel is shown as a solid plate with smaller perforations.

[0068] Figure 4b shows some panels, which are shaped to fit and cover the openings in the framework. These are lowered into the tank, preferably individually, so that the fish can swim around the panels as they are lowered.

[0069] Figure 4c shows an example of how pairs of panels can be lowered together. They are hinged so that they can be in a vertical position when lowered and then laid down to a horizontal position when they have reached the frame.

[0070] Figure 5 schematically shows some of the elements in a rearing tank. We see the tank wall, the central column, and the walkway, and we see the two components of the crowding grid, i.e., a framework and a number of panels. Further, we see wires attached from the framework and the panels to a higher point. These wires are used to lower and raise the framework and panels.

[0071] Figure 6 schematically shows how the framework hangs above the liquid surface in an upper storage position.

[0072] Figure 7 shows how the framework is lowered to the bottom of the tank, and also one of the panels on its way down to the framework.

[0073] Figure 8 schematically shows a tank for rearing marine organisms, and two crowding grid units, each having open and closed sections, which can be introduced into the tank.

[0074] Figure 9 schematically shows the same tank as in Figure 1 , but where the two crowding grid units have moved to a lower (bottom of the tank) inactive position. The fish are in the tank above the lowered crowding grid units. The figure shows the crowding grid units (which in this embodiment are identical) partially rotated relative to each other, so that there are still some open sections and some sections closed off to the fish.

[0075] Figure 10 schematically shows the same solution as in Figure 9, but where the two crowding grid units have now been rotated further relative to each other, so that the two crowding grid units now provide a "tight" grid across the entire framework, i.e., so that only liquid can pass through the crowding grid units. The crowding grid is now ready to be lifted from this inactive position upwards in the tank, thus also crowding the fish upwards in the tank.

[0076] Figure 11 shows the crowding grid in an upper position, i.e., after it has crowded the fish upwards (and out of) the tank.

[0077] Detailed description of preferred embodiments of the invention

[0078] As described in PCT / N02023 / 000002, a grader is used, which is raised from a submerged inactive position at the bottom of the breeding tank to grade (concentrate) fish in an upper part of the tank. The problem with this solution is that the grader cannot be positioned in the inactive lower position while there are marine organisms (fish) in the tank. The grader must be inserted into the tank before the tank is filled with fish.

[0079] Furthermore, N020240046 describes a solution where a framework with loose panels can be lowered into a breeding tank. The panels are lowered detached from the framework so that there are openings in the framework through which the fish can swim. When the framework is in its lower position, the panels are assembled with the framework, and a grid is then established which is impermeable to the fish, but which the liquid can flow through, and when this framework is moved upwards in the tank, the fish will also be forced upwards.

[0080] The present invention solves the problem in N020240046 with loose panels, which must be assembled with the framework at the bottom of the tank. The solution provided consists of using at least two grading units, each of which has closed (with a grid) and open sections, so that the two units can be lowered into the tank with open sections arranged over each other (i.e., so that fish can pass), and when the grading units are in the lower part of the tank, they are rotated relative to each other so that the grids (the closed sections for the fish) fill the entire framework, i.e., the grading units together form a grid that covers the entire inner circumference of the breeding tank.

[0081] Figure 8 shows a tank 12, such as a breeding tank 12 for the breeding of marine organisms, for example, fish. The figure also shows two grading units 17, each comprising open sections 17a and sections 17v consisting of a grid or a net material. The grid sections 17b are sometimes called closed sections because they are impermeable to marine organisms.

[0082] You do not want to have grading units 17 permanently installed at the bottom of the tank 12 due to the risk of sediment accumulation, as well as the disruptive effect on the water flow in the tank 12. The grading units 17 are therefore parked above the water level so that you have a clean and smooth tank 12 where the fish reside. The grader can typically hang under walkways, etc.

[0083] The challenge is then to get the grading units 17 under the fish before grading the fish upwards. This is solved by the fact that the grading units 17 essentially consist of two different sections, open sections 17a where both fish and liquid can pass through, and closed grid sections 17b where only liquid can pass through. The framework 16a forms a structure that has an inner circle that will enclose the center pipe 18, and an outer circle that will be adapted to the shape of the circumference of the tank 12 (inside the walls 12a). There are large openings 17a in the framework 16a through which the fish can swim when the framework is lowered from the storage position down into the tank.

[0084] Figure 9 shows how the framework 16a with two grading units 17 is now lowered to the lower inactive position. The marine organisms have now moved to a position above the framework 16a and the grading units 17. The figure shows that the two grading units are slightly rotated relative to each other, establishing one or more open sections 17a. The fish can swim through these open sections 17a when the grading units are lowered to the lower inactive position (as shown in Figure 9).

[0085] Figure 10 shows how the grading units have been rotated relative to each other so that there are now no open sections; the entire grader is closed and now only consists of closed grid sections 17b. The grading units are in Figure 10 arranged down in the tank (in an inactive position) and are now ready to be raised upwards in the tank 12. The fish cannot pass through the grading units 17 in this configuration, and the fish are forced upwards in the tank as the grading units are raised.

[0086] Figure 11 shows the grading units 17 after they have been raised to an upper position. The fish have now been forced upwards and out of the tank.

[0087] The solution according to the invention may consist of 2 or more crowding grid units 17. For example, one can have a magazine with several crowding grid units, and one can move a large number of crowding grid units down to the lower part of the tank 12 at the same time. This presupposes that the crowding grid units 17 have been rotated relative to each other so that they all have openings 17a in the same section of the crowding grid units 17. They can then, for example, be pushed up with two crowding grid units simultaneously, which will be sufficient if they have equally large open and closed sections, and if these can be arranged so that two crowding grid units will form a completely closed crowding grid unit 17 when it is pushed upwards in the tank 12.

[0088] Together with the crowding grid units 17, a suction arrangement (as described in PCT / N 02023 / 000002) may be arranged. When the crowding grid is to crowd the fish for transfer to a new tank, the crowding grid units 17 are moved upwards while the suction arrangement 14 is also moved upwards. The suction arrangement 14 therefore has a flexible pipe, such as a hose.

[0089] The crowding grid units 17 are permeable to liquid, i.e. , the water in which the fish reside flows freely through the crowding grid units 17. The openings in the grid sections 17b of the crowding grid units 17 are sufficiently small that the marine organisms cannot move from one side of the crowding grid units 17 to the other.

[0090] When the crowding grid units 17 have two open sections 17a lying above each other, i.e., the configuration they have when lowered into the tank 12, the crowding grid units 17 are also permeable to fish, i.e., the fish can move from a position below the crowding grid units 17 to a position above the crowding grid units 17 as the framework 16 with crowding grid units 17 is lowered into the tank.

[0091] The framework 16 and the crowding grid units 17 can be attached to the tank wall 12a and the outer sides of the central column 18 via guides on the tank wall 12a and the central column 18, respectively. These guides are not shown in the figures, but they can be in the form of slots in which pins on the grid are moved vertically up and down. Alternatively, the framework 16a and the crowding grid units 17 are attached with wires used to lower and raise the framework 16 and the crowding grid units 17.

[0092] In a preferred embodiment, the crowding grid units 17 are arranged vertically higher at the outer periphery than at the center, so that the crowding grid is positioned sloping towards the center of the tank 12. This will cause the fish to be led towards the center when crowded.

[0093] The crowding grid units preferably consist of an outer ring and an inner ring, where the outer ring is higher than the inner one, so that when the grid is raised in the tank 12, the fish will feel threatened and seek down towards this and be led towards the center and towards the suction of the flexible hose, i.e., towards the suction arrangement 14, and be led up and out of the tank 12. This design also ensures that when the crowding grid 16 comes all the way up, the last remaining fish are drawn towards the center and into the channel and sucked up. In a preferred embodiment, the suction arrangement 14 is connected to a siphon, so that the siphon principle is used to lead the fish out of the tank 12. Alternatively, or in combination, the fish can be sucked out of the tank with the help of a pump.

[0094] Preferably, the crowding grid units 17, near the center, are equipped with a circular channel 16a. The fish will be led towards and seek down into this channel 16a when crowded.

[0095] Preferably, the channel 16a is equipped with one or more recesses 16b, and the suction arrangement is preferably arranged in one or more of these recesses 16b.

[0096] With this solution, it has been achieved that the fish can be gently led out of a tank and possibly over to a new tank by raising the crowding grid units 17 in the tank 12. The crowding will result in the fish gathering just above the crowding grid units 17 and the center of the tank. They are then led via the channel 16a, and preferably the recess 16b, to the suction arrangement 14, which leads the fish out of the tank 12. Since the solution is very gentle on the fish, it will be especially suitable for tanks 12 where the fish are to stay for shorter periods, e.g., for slaughter tanks.

[0097] Figure 1 shows a tank 12, such as an aquaculture tank 12 for rearing marine organisms, for example, fish. A central element of the invention is the framework 16a, shown here arranged in an upper position, called the storage position. The framework 16a will be in this position when not in use.

[0098] A crowding grid 16 is not desired to be permanently installed at the bottom due to the risk of sludge accumulation and the disturbing effect on the water flow in the tank 12. Therefore, the crowding grid 16 is parked above the water level, providing a clean and smooth tank 12 where the fish reside. The crowding grid can typically hang under walkways, etc.

[0099] The challenge is to get the crowding grid 16 under the fish before crowding the fish upwards. This is solved by the fact that the crowding grid essentially consists of two components, a framework 16a and a number of panels 16b. The framework 16a forms a structure with an inner circle that will surround the central column 18 and an outer circle adapted to the circumference of the tank 12 (within the walls 12a). There are large openings in the framework 16a through which the fish can swim when the framework is lowered from the storage position into the tank.

[0100] Figure 2 shows how the framework 16a is now lowered to the lower inactive position. The marine organisms have now moved to a position above the framework.

[0101] Figure 4 shows how a set of panels 16b (here four pieces) is lowered from an upper position down towards the framework 16a at the bottom of the tank 12. Preferably, one panel at a time is lowered, so the fish have plenty of space to swim around the panels. Alternatively, the panels can be lowered in a vertical position, for example, as shown in Figure 4c, which shows how two panels are hinged together. These are lowered in a vertical position and then rotated to a horizontal position when they come into contact with the framework 16a. The point of dividing the crowding grid 16 into two components (and several parts) is that it can be lowered into the tank while the fish can move from a position under the crowding grid 16 to a position above the crowding grid. The framework 16a and panels 16b are then automatically assembled at the bottom of the tank into a crowding grid 16. When this crowding grid 16 is pushed / pulled upwards, the fish will be crowded into a smaller water volume in the upper part of the tank.

[0102] Figure 4b schematically shows a set of panels, and Figure 4c shows how pairs of panels can be hinged together.

[0103] Together with the crowding grid, a suction arrangement (as described in PCT / N 02023 / 000002) may be arranged. When the crowding grid is to crowd the fish for transfer to a new tank, the crowding grid 16 is moved upwards while the suction arrangement 14 is also moved upwards. The suction arrangement 14 therefore has a flexible pipe, such as a hose.

[0104] The crowding grid 16 is permeable to liquid, i.e. , the water in which the fish reside flows freely through the crowding grid 16. The openings in the crowding grid are sufficiently small that the marine organisms cannot move from one side of the crowding grid to the other.

[0105] When the crowding grid 16 is divided into its components; framework 16a and panels 16b, the components are also permeable to fish, i.e., the fish can move from a position under the components to a position above the components as the framework and panels are lowered into the tank.

[0106] The components of the crowding grid 16 can be attached to the tank wall 12a and the outer sides of the central column 18 via guides on the tank wall 12a and the central column 18, respectively. These guides are not shown in the figure but can be in the form of slots in which pins on the grid are moved vertically up and down. Alternatively, the framework 16a and the panels 16b are attached with wires used to lower the framework 16 and panels 16b, to raise the crowding grid 16.

[0107] In a preferred embodiment, the crowding grid 16 is arranged vertically higher at the outer periphery than at the center, so that the crowding grid is positioned sloping towards the center of the tank, causing the fish to be led towards the center when crowded. The crowding grid preferably consists of an outer ring and an inner ring, where the outer ring is higher than the inner ring. Thus, when the grid is raised in the tank 12, the fish will feel threatened and seek down towards it, being led towards the center and into the suction of the flexible hose, and led up and out of the tank 12. This design also ensures that when the crowding grid 16 comes all the way up, the last remaining fish are drawn towards the center and into the channel 16a and sucked up.

[0108] In a preferred embodiment, the suction arrangement is connected to a siphon, so that the siphon principle is used to lead the fish out of the tank 12. Alternatively, or in combination, the fish can be sucked out of the tank with the help of a pump.

[0109] Preferably, the crowding grid, near the center, is equipped with a circular channel 16a. The fish will be led towards and seek down into this channel 16a when crowded. Preferably, the channel 16a is equipped with one or more recesses 16b, and the suction arrangement is preferably arranged in one or more of these recesses 16b.

[0110] With this solution, it has been achieved that the fish can be gently led out of a tank, and possibly over to a new tank, by raising a crowding grid 16 in the tank 12. The crowding will result in the fish gathering just above the crowding grid 16 and the center of the tank. They are then led via the channel 16a, and preferably the recess 16b, to the suction arrangement 14, which leads the fish out of the tank 12. Since the solution is very gentle on the fish, it will be particularly suitable for tanks where the fish are to stay for shorter periods, e.g., slaughter tanks.

[0111] We will also briefly describe an additional embodiment of the invention: The device may comprise only one crowding frame (for example, the upper one shown in the figures) with a battery of panels lying like in a magazine above each other, and the upper frame rotates and pulls out one element at a time from the "magazine" until the entire circumference of the crowding grid is covered.

Claims

Patent Claims1. Device (10) for crowding and moving live marine organisms from a tank (12), wherein the device comprises one or more horizontally arranged perforated crowding grids (16), where the crowding grids (16) are arranged to be raised from an inactive position at the bottom of the tank (12) and vertically upwards for crowding liquid and the marine organisms out of the tank (12), characterized in that the crowding grids (16) comprise panels (16b) or crowding grid units (17a, 17b), where the panels (16b, 17a, 17b) are open (16b, 17a) or comprise a grid (17b), where the crowding grids (16) can be moved from a storage position above the liquid level in the tank (12) to the lower inactive position, where the crowding grids (16) as they are lowered in the tank have at least one open panel / unit (16b, 17a) so that the marine organisms can move through the crowding grids (16), and where the panels / units (16b, 17a, 17b) are repositioned in the lower position so that the crowding grids (16) do not comprise any open sections and thereby crowd the marine organisms upwards in the tank (12) as the crowding grids are raised upwards in the tank (12).

2. Device (10) in accordance with claim 1 , characterized in that a crowding grid (16) comprises two or more crowding grid units (17a, 17b) arranged to be rotatable relative to each other, and where these crowding grid units comprise a framework (16a) and a number of panels (16b) that are open (17a) or formed by a grid (17b), where at least one of the panels in each crowding grid unit (17) is open, so that the crowding grid (16) can be moved from a storage position above the liquid level in the tank (12) to the lower inactive position with two panels (17) with openings (17a) arranged above each other so that the marine organisms can move through the crowding grid (16), and that when the crowding grid is in the lower inactive position, the crowding grid units (17a, 17b) are rotated relative to each other so that a perforated crowding grid is established that extends between the tank (12) wall sections (12a).

3. Device in accordance with claim 1 , characterized in that a flexible element is arranged between the tank walls (12a) and the outer circumference of the perforated crowding grid (16), and between the crowding grid (16) and the central column (18) to seal the distance between the tank wall (12a) and the crowding grid (16).

4. Device in accordance with claim 3, characterized in that the mentioned flexible element is a flexible hose arranged to be pressurized with water to seal between the frame and the tank wall (12a) / central column (18).

5. Device (10) in accordance with claim 1 , characterized in that the crowding grid (16) is raised in the tank (12) while a constant water flow is introduced into and up into the suction arrangement (14).

6. Device (10) in accordance with claim 1 , characterized in that the device comprises a suction arrangement (14) for removing liquid and marine organisms, where the suction arrangement (14) is arranged centrally just above the horizontally perforated crowding grid (16).

7. Device (10) in accordance with claim 1 , characterized in that the crowding grid (16) moves vertically up and down in the tank (12), movably attached to vertical guides along the central column (18) and tank wall (12a).

8. Device (10) in accordance with claim 1 , characterized in that the framework (16a) and the panels (16b) are each attached with ropes, cables, or wires (16c) to an element arranged above the tank (12).

9. Device in accordance with claim 1 , characterized in that the assembly of the crowding grid (16) has a channel in the center, arranged so that fish are crowded towards this channel when the crowding grid (16) is moved upwards.

10. Device (10) in accordance with claim 9, characterized in that the crowding grid (16) channel comprises at least one recess.

11. Device (10) in accordance with claim 10, characterized in that one or more panels have a recess of net material where the suction arrangement is positioned.

12. Device (10) in accordance with claim 10, characterized in that the suction arrangement (14) is arranged in the mentioned recess or channel.

13. Device (10) in accordance with claim 1 , characterized in that the framework (16a) is constructed as a framework with an inner and outer ring with soft flexible lamellae, preferably made of a plastic material, against the tank wall (12a) and central column (18).

14. Device (10) in accordance with claim 6, characterized in that the assembly of the crowding grid (14) is designed so that the center of the crowding grid (14) and the suction arrangement (14) are arranged vertically lower than the outer edge of the crowding grid (16).

15. Device in accordance with claim 1 , characterized in that the panels (17b) have a grid structure made of net, grid, or grille material with openings adapted to the size of the marine organisms in the tank (12), so that they do not pass through the openings inthe crowding grid (16) as it has no open sections (17a) arranged above each other, but the liquid flows freely through the crowding grid (16).

16. Device in accordance with claim 6, characterized in that the suction arrangement (14) is connected to a siphon that lifts the marine organisms out of the tank (12) through a flexible conduit (14a).

17. Device in accordance with claim 1 , characterized in that the stress level and position of the marine organisms are monitored, and this information is used to control the raising of the horizontally assembled crowding grid (16).

18. Device in accordance with claim 17, characterized in that visual and acoustic methods, such as camera, hydrophone, and / or radar, are used to monitor the stress level and position of the marine organisms.

19. Device in accordance with claim 1 , characterized in that a crowding grid (16) comprises a framework (16a) and a number of panels (16b) so that the crowding grid (16) can be moved from a storage position above the liquid level in the tank (12) to the lower inactive position by first lowering the framework (16a) into the tank, and then lowering the panels and positioning them on the framework (16a) to establish a perforated crowding grid that extends between the tank (12) wall sections (12a).

20. Device in accordance with claim 19, characterized in that a flexible element is arranged between the tank walls (12a) and the outer circumference of the perforated crowding grid (16), and between the crowding grid (16) and the central column to seal the distance between the tank wall (12a) and the crowding grid (16).21 . Device in accordance with claim 20, characterized in that the mentioned flexible element is a flexible hose arranged to be pressurized with water to seal between the frame and the tank wall (12a) / central column.

22. Device (10) in accordance with claim 19, characterized in that the crowding grid (16) is raised in the tank (12) while a constant water flow is introduced into and up into the suction arrangement (14).

23. Device (10) in accordance with claim 19, characterized in that the device comprises a suction arrangement (14) for removing liquid and marine organisms, where the suction arrangement (14) is arranged centrally just above the horizontally perforated crowding grid (16).

24. Device (10) in accordance with claim 19, characterized in that the crowding grid (16) moves vertically up and down in the tank (12) movably attached to vertical guides along the central column (18) and tank wall (12a).

25. Device (10) in accordance with claim 19, characterized in that the framework (16a) and the panels (16b) are each attached with ropes, cables, or wires (16c) to an element arranged above the tank (12).

26. Device in accordance with claim 19, characterized in that the assembly of the crowding grid (16) has a channel (16d) in the center, arranged so that fish are crowded towards this channel (16d) when the crowding grid (16) is moved upwards.

27. Device (10) in accordance with claim 26, characterized in that the crowding grid's (16) channel (16a) comprises at least one recess (16e).

28. Device (10) in accordance with claim 26, characterized in that one or more panels have a recess of net material where the suction arrangement is positioned.

29. Device (10) in accordance with claim 27, characterized in that the suction arrangement (14) is arranged in the mentioned recess (16b) or channel (16d).

30. Device (10) in accordance with claim 21 , characterized in that the framework (16a) is constructed as a framework with an inner and outer ring with soft flexible plastic-like lamellae against the tank wall (12a) and central column (18).31 . Device (10) in accordance with claim 23, characterized in that the assembly of the crowding grid (14) is designed so that the center of the crowding grid (14) and the suction arrangement (14) are arranged vertically lower than the outer edge of the crowding grid (16).

32. Device in accordance with claim 19, characterized in that the panels (16a) have a grid structure made of net, grid, or grille material with openings adapted to the size of the marine organisms in the tank (12), so that they do not pass through the openings in the crowding grid (16), but the liquid flows freely through the crowding grid (16).

33. Device in accordance with claim 23, characterized in that the suction arrangement (14) is connected to a siphon that lifts the marine organisms out of the tank (12) through a flexible conduit (14a).

34. Device in accordance with claim 19, characterized in that the stress level and position of the marine organisms are monitored, and this information is used to control the raising of the horizontally assembled crowding grid (16).

35. Device in accordance with claim 34, characterized in that visual and acoustic methods, such as camera, hydrophone, and / or radar, are used to monitor the stress level and position of the marine organisms.

36. Method for crowding marine organisms in a tank (12), characterized in that a horizontally arranged crowding grid (16) is moved from an inactive position at the bottom of the tank (12) upwards in the water column to crowd the fish to the upper level in the tank (12), characterized in that the crowding grid can be moved from a storage position above the liquid level to the inactive position at the bottom of the tankas the crowding grid (16) is an assembly of two or more crowding grid elements (17a, 17b), each with a number of open panels (17a) and a number of grid panels (17b), and that the crowding grid elements (17a, 17b) can be rotated relative to each other so that the crowding grid elements (17a, 17b), together are moved down into the tank to the inactive position with two open panels (17a) arranged above each other, where the two crowding grid elements (17a, 17b) are rotated relative to each other in the inactive position, and establish a crowding grid (16) with grid (17b) in all panels, where the marine organisms are moved out of the tank (12) as they seek towards the center of the crowding grid (16) in the upper part of the tank (12) as the crowding grid moves upwards in the tank (12).

37. Method for crowding marine organisms in a tank (12), characterized in that a horizontally arranged crowding grid (16) is moved from an inactive position at the bottom of the tank (12) upwards in the water column to crowd the fish to the upper level in the tank (12), characterized in that the crowding grid can be moved from a storage position above the liquid level to the inactive position at the bottom of the tank as the crowding grid (16) is an assembly of a frame (16a) and a number of panels (16b) that are each moved down into the tank to the inactive position, where the marine organisms are moved out of the tank (12) as they seek towards the center of the crowding grid (16) in the upper part of the tank (12) as the crowding grid moves upwards in the tank (12).

38. Method in accordance with claim 36 or 37, characterized in that a suction arrangement (14) is located just above the crowding grid (14) arranged to suck water and marine organisms out of the tank (12).

39. Method in accordance with claim 36 or 37, characterized in that the crowding grid (16) is moved from an inactive low position in the tank (12) and upwards in the tank (12) for crowding the marine organisms towards the center and to a location just above the crowding grid (16).

40. Method in accordance with claim 36 or 37, characterized in that the crowding grid (16) in its innermost edge section is equipped with a channel (16a), and that the fish are led towards this channel (16a) when crowded, and that the suction arrangement (14) is positioned in this recess (16b).41 . Method in accordance with claim 36 or 37, characterized in that said channel (16a) is provided with at least one recess (16b) so that the fish is guided into this recess (16b) during crowding, and that the suction arrangement (14) is positioned in this recess (16b).