A harvesting assembly and method for aquatic organisms

Abstract

A harvesting assembly for aquatic organisms comprises a harvesting unit (4) and an inflow device (5). The harvesting unit (4) comprises a container (1) having an internal cavity (7) configured for holding a liquid and aquatic organisms and comprising a first inflow opening (15). The inflow device (5) comprises a second inflow opening (13) and a valve device (9) configured for allowing liquid and aquatic organisms to flow through the inflow openings and into the cavity, and at least a portion of the inflow device (5) is arranged in the first inflow opening (15). An outflow conduit (16) is fluidly connected to a lower portion the cavity (7), and one or more pump devices (18) are configured and arranged for discharging water from the cavity. The method involves lifting the harvesting assembly out of the water when a desired amount of aquatic organisms has been harvested, whereby the cavity contents are allowed to drain out through the outflow conduit.

Description

[0001] A HARVESTING ASSEMBLY AND METHOD FOR AQUATIC ORGANISMS Technical field of the invention

[0002] The invention concerns the field of aquaculture. More specifically, the invention concerns a harvesting assembly as defined by claim 1 and an associated harvesting method as defined by claim 14.

[0003] Background of the invention

[0004] Plankton are a diverse group of aquatic organisms that includes zooplankton, such as krill. Zooplankton is a major ocean resource with considerable human and economic potential but harvesting it is complicated and costly for various reasons. Historically, zooplankton has been harvested by large nets or a trawl with a very small mesh size. This technology involves the use of trawlers and support vessels and often causes considerable bycatch.

[0005] The prior art includes WO 2016 / 096832 Al, which describes an underwater system for harvesting zooplankton or mesopelagic fishes, comprising an underwater vehicle for being lowered into the sea and towed behind a surface vessel, comprising a housing provided with an inlet through which zooplankton-containing-fluid may flow; a hose mounted on the underwater vehicle and in fluid communication with the inlet, the hose being adapted to secure and fluidly connect the underwater vehicle to the surface vessel; and pumping means for drawing in a zooplankton-containing-fluid through the inlet in the underwater vehicle and for pumping the zooplankton-containing-fluid through the hose to the surface vessel. A laser emits light at a wavelength suitable for attracting zooplankton.

[0006] The prior art also includes WO 2019 / 101830 Al, which describes a system for harvesting zooplankton or mesopelagic fishes, comprising an underwater device for being lowered and towed into the sea, said underwater device comprising a housing provided with one or more inlets adapted to receive a zooplankton or mesopelagic fishes-containing fluid, wherein said housing comprises one or more manifolds. The underwater device further comprises one or more sources of light facilitating schooling of zooplankton towards an illuminated area, and a connection fluidically connecting the underwater device to a surface vessel; wherein said one or more inlets are inlets to said one or more manifolds and said one or more manifolds converge into said fluidic connection, wherein said one or more sources of light are located within said one or more inlets.

[0007] An object of the invention is to provide a system and a method that are less energydemanding and less dependent on support vessels, and that can be used for harvesting aquatic organisms such as zooplankton and juvenile fish.

[0008] Summary of the invention

[0009] The invention is set forth and characterized in the main claim, while the dependent claims describe other characteristics of the invention.

[0010] It is thus provided a harvesting assembly for aquatic organisms, characterized by: - a harvesting unit comprising a container having an internal cavity configured for holding a liquid and aquatic organisms and comprising a first inflow opening;

[0011] - an inflow device having a second inflow opening and a valve device configured for allowing liquid and aquatic organisms to flow through the inflow openings and into the cavity, and wherein at least a portion of the inflow device is arranged in the first inflow opening;

[0012] - an outflow conduit fluidly connected to a lower portion the cavity; and

[0013] - one or more pump devices configured and arranged for discharging water from the cavity.

[0014] In one embodiment, the inflow device comprises an elongate conduit having a first interface portion in one end and the second inflow opening at another end, and the first interface portion and a second interface portion in the cavity are configured for mating engagement to form a sealed connection between the harvesting unit and the inflow device. In one embodiment, the first interface portion and the second interface portion are releasable connections.

[0015] The harvesting unit may comprise one or more buoyancy devices for supporting the harvesting assembly in a body of water.

[0016] In one embodiment, an outflow filter device is provided in the cavity upstream of the one or more pump devices’ inlet, the outflow filter device having a mesh size that prevents aquatic organisms above a desired size to be expelled from the cavity when the harvesting assembly is arranged and in operation in a body of water. In one embodiment, one or more light sources are arranged in the vicinity of the second inflow opening and configured for emitting light that attracts aquatic organisms that are desired to harvest.

[0017] In one embodiment, the outflow conduit is a flexible conduit and is configured for extending to an upper portion of the harvesting unit, above the water surface of a body of water when the harvesting assembly is arranged and in operation in the body of water. The valve device can be a one-way valve, permitting fluid flow only into the cavity.

[0018] In one embodiment, an inflow filter device is arranged in the inflow device, in the vicinity of the second inflow opening, or in the first inflow opening. In one embodiment, an outflow filter device is arranged in the upper region of the cavity, upstream of the inlet to the one or more pumps. A mesh size of the outflow filter device is smaller than a mesh size of the inflow filter device.

[0019] In one embodiment , the harvesting assembly comprises an intermediate inflow device releasably or permanently connected to the container lower portion. In one embodiment, the intermediate inflow device is connected to the first inflow opening and the free end of the intermediate inflow device is configured for releasable connection to the first interface portion of the inflow device .

[0020] It is also provided a harvesting method for aquatic organisms, by using the harvesting assembly according to the invention, the characterized by:

[0021] a) arranging the harvesting assembly in a body of water such that the inflow device extends downwards; and;

[0022] b) operating the one or more pump devices to discharge water from the cavity and thus causing water to flow into the cavity via the first inflow opening.

[0023] In one embodiment of the method, step a is preceded by:

[0024] a-2) arranging the harvesting unit (4) floating in the body of water (W); and

[0025] a-1) arranging at least a portion of the inflow device (5) in the first inflow opening (15). In embodiments of the method, step b is followed by:

[0026] c) at a desired point in time, discontinue operation of the one or more pump devices and;

[0027] d) lift the harvesting assembly out from the body of water, whereby the contents of the cavity are allowed to flow through the outflow conduit, by gravity, by a pump system, or a combination.

[0028] In one embodiment of the method, lights in the vicinity of the second inflow opening are activated to attract aquatic organisms.

[0029] In embodiments of the method, wherein the harvesting assembly comprises

[0030] - an outflow filter device provided in the cavity upstream of the one or more pump devices’ inlet, the outflow filter device having a mesh size that prevents aquatic organisms above a desired size to be expelled from the cavity when the harvesting assembly is arranged and in operation in a body of water;

[0031] - an inflow filter device arranged in the inflow device, in the vicinity of the second inflow opening, or in the first inflow opening; and

[0032] - one or more light sources arranged in the vicinity of the second inflow opening and configured for emitting light that attracts aquatic organisms that are desired to harvest; the harvesting method further comprises the steps of:

[0033] - configuring the inflow filter device and the outflow filter device for catching and retaining, respectively, fish of a size corresponding to the specified type of fish;

[0034] - operating and controlling the one or more light sources to emit light at wavelengths appropriate for attracting the specified type of fish;

[0035] - when a desired quantity of the specified type of fish has entered the cavity, configuring the inflow filter device for catching aquatic organisms suitable as feed for the specified type of fish; and

[0036] - operating and controlling the one or more light sources to emit light at wavelengths appropriate for attracting the specified type of aquatic organisms suitable as feed for the specified type of fish.

[0037] As opposed to the prior art harvesting devices, the invented harvesting assembly can operate without a supporting vessel. A vessel is only needed to empty the container and - if needed - charge bateries. The pump (or pumps) needs very litle energy since water is not being pumped into the cavity above sea-level.

[0038] Brief description of the drawings

[0039] These and other characteristics of the invention will become clear from the following description of embodiments of the invention, given as non-restrictive examples, with reference to the atached schematic drawings, wherein:

[0040] Figure 1 illustrates an inflow device according to a first embodiment of the invention;

[0041] Figure 2 illustrates a harvesting unit according to a first embodiment of the invention;

[0042] Figure 3 illustrates an inflow device being lowered into a harvesting unit, wherein the later is floating in a body of water;

[0043] Figure 4 illustrates a harvesting assembly according to a first embodiment of the invention, floating in a body of water;

[0044] Figures 5 and 6 illustrate a harvesting assembly in operation in a body of water; Figure 7 illustrates a harvesting assembly being emptied of its contents;

[0045] Figure 8 illustrates an inflow device according to a second embodiment of the invention;

[0046] Figure 9 illustrates a harvesting unit according to a second embodiment of the invention;

[0047] Figure 10 illustrates a step in a procedure for interconnecting an inflow device and a harvesting unit to form a harvesting assembly according to a second embodiment of the invention, floating in a body of water;

[0048] Figure 11 illustrates the harvesting assembly illustrated in figure 10, in operation in a body of water; and

[0049] Figure 12 illustrates a harvesting assembly being emptied of its contents. Detailed description of embodiments of the invention

[0050] The following description may use terms such as “horizontal”, “vertical”, “lateral”, “back and forth”, “up and down”, ’’upper”, “lower”, “inner”, “outer”, “forward”, “rear”, etc. These terms generally refer to the views and orientations as shown in the drawings and that are associated with a normal use of the invention. The terms are used for the reader’s convenience only and shall not be limiting.

[0051] Referring initially to figure 4, the harvesting assembly according to a first embodiment of the invention comprises a harvesting unit 4 and an inflow device 5.

[0052] The harvesting unit 4 comprises a container 1, in the illustrated embodiment in the form of a tank having an internal cavity 7. The container comprises a material and structure suitable for the intended use and purpose, preferably a rigid structure. The container cavity 7 is configured for holding a liquid such as water and harvested aquatic organisms. The harvesting unit 4 can be configured for floating in a body of water W and can therefore comprise a buoyancy device 17. The buoyancy device can be any such device or assembly known in the art. In the illustrated embodiment the buoyancy device is arranged and configured such that an upper portion of the harvesting unit 4 is extending above the water surface S when the harvesting unit is arranged and in operation in a body of water. One or more pumps 18 are arranged on the harvesting unit 4 for pumping water out from the cavity 7. Referring additionally to figure 2, a first inflow opening 15 is arranged in a lower portion of the container 1, thus providing a fluid conduit between the cavity 7 and water around the container.

[0053] An outflow conduit 16 is fluidly connected to a lower portion of the cavity 7, via a connection 29 near or at the tank bottom. The outflow conduit 16 is configured and arranged such that it will allow the cavity contents to flow through the conduit when certain conditions are fulfilled, and thus empty the cavity, as is described below. In the illustrated embodiment, the outflow conduit 16 is a flexible hose extending along the length of the harvesting unit and arranged such that its free end, with an outflow opening 26, is above the water surface W when the harvesting unit is arranged in a body of water as illustrated in figure 4. In one embodiment, the outflow conduit 16 comprises an outflow valve 30 for controlling outflow from the cavity 7, for example a manually operated valve or a one-way valve. In figure 2, the outflow valve 30 is arranged near the outflow opening 26, but it should be understood that this valve may be arranged anywhere between the connection 29 and the outflow opening 26. The valve 30 is optional; in an alternative embodiment, the outflow conduit comprises a lid or other movable restriction device.

[0054] Referring to figures 1 and 4, the inflow device 5 in the illustrated embodiment is releasably connected to the harvesting unit 4 via a first interface portion 10 in an upper end of the inflow device 5 abutting against a second interface portion 14 inside the cavity 7. The first and second interface portions have complementary shapes such they form a sealed connection when the inflow device 5 is installed in the harvesting unit 4 as shown in figure 4. The inflow device 5 comprises a valve 9 whereby flow into the cavity 7 may be controlled. In the illustrated embodiment, the valve 9 is a one-way valve permitting water and aquatic organisms to only flow into the cavity 7. In the illustrated embodiment, the valve 9 is arranged in the upper end of the inflow device, but it should be understood that this valve may be arranged elsewhere in the inflow device 5 or in the first inflow opening 15.

[0055] In the illustrated embodiment, the inflow device 5 comprises an inflow conduit 11 comprising the above-mentioned one-way valve 9 and having the above-mentioned first interface portion 10 at one (upper) end and a second inflow opening 13 at the other (lower) end. One or more light sources 12 are arranged in the vicinity of the second inflow opening 13. The light sources can be remotely controlled. The purpose of the light source (or light sources) is to attract aquatic organisms intended to be harvested, for example zooplankton or juvenile fish, and the one or more light sources 12 are thus controllable to emit light at the appropriate wavelength. Such technology is well known in the art.

[0056] The inflow conduit 11 length can be anywhere between less than a meter and several tens of meters, such that the second inflow opening 13 is positioned at the desirable water depth when the harvesting assembly is arranged in the water and is in use. The invention is therefore not limited by the length of the inflow conduit 11. In the illustrated embodiment, the inflow conduit 11 is a flexible hose, but it may have other characteristics and designs. As the harvesting unit in the illustrated embodiment is arranged with its upper portion in the water surface, and the aquatic organisms intended to be harvested oftentimes are found at several meters below, the inflow conduit 11 may be several meters long. From an operational perspective, it is convenient that the harvesting unit 4 and the inflow device 5 are separate and releasably connected objects that can be installed sequentially on site in the body of water. Such installation sequence is illustrated in figures 3 and 4. In figure 3, the harvesting unit 4 has been installed in a body of water W and is supported by the buoyancy device 17 such that an upper portion of the container 1 is extending a distance above the water surface. The majority of the container is below the water surface. The harvesting unit 4 is provided with a tether 2 by means of which its lateral position in the water may be controlled. In the illustrated configuration, seawater is allowed to flow into the cavity 7 via the first inflow opening 15. A separate valve (not shown) may be arranged in the first inflow opening and is open when the harvesting unit is arranged in the water. The inflow device 5 is subsequently lowered into the cavity 7, through an opening at the top of the container 1 that otherwise can be kept closed by a cap 19. The lowering operation is performed and controlled by a crane device 20 on a boat (or other suitable platform) 3 and a wire 6 connected to a lifting arrangement 27 (see figure 1) in the upper end of the inflow device 5. A wire 8 for supplying power to the lights 12 may be attached to or integrated with the lifting wire 6 until the lifting arrangement 27 and then extending inside the inflow conduit 11 down to the lights. It should, however, be understood that the lights may be powered and controlled by other devices arranged at other locations.

[0057] The inflow device 5 is lowered further into the cavity 7 and into the first inflow opening 15 until the first and second interface portions 10, 14 abut and thereby form a sealed connection between the container (i.e. the cavity 7) and the inflow device 5. The inflow device 5 is now (as shown in figure 4) supported by the harvesting unit 4. In this configuration, as long water pressure in the cavity 7 is equal to or greater than the water pressure outside the container 1, the one-way valve 9 ensures that water is not flowing out from the cavity through the inflow conduit 11.

[0058] Figures 5 and 6 illustrate the harvesting assembly (comprising the harvesting unit 4 and the inflow device 5) installed and in operation in a body of water W. The assembly is secured to a buoy 21 via a tether 2 connected to the harvesting unit 4, and the buoy 21 is tied to an anchor or mooring 24 on the seabed B via a rope or mooring line 23. The pump (or pumps) 18 is operated to discharge water from within the cavity 7, illustrated by arrows D in figure 6. Therefore, when the pump (or pumps) 18 is operating and water is being discharged from the cavity 7, water pressure in the cavity is less than the water pressure outside the container 1 and the one-way valve 9 opens, which causes water to be drawn from the body of water and into the cavity 7 via the second inflow opening 13 in the inflow device (and thus the first inflow opening 15 in the cavity). Aquatic organisms in the vicinity of the inflow opening 13 are therefore also drawn into the cavity.

[0059] The pump speed, and hence the rate at which water is being discharged from the cavity, can be controlled, whereby the rate at which water and aquatic organisms present near the second inflow opening is being drawn into the cavity is correspondingly controlled. It will be understood that the water will continue to flow into the cavity through the inflow conduit 11 as long at the pressure difference (between water pressure inside the cavity and water pressure outside the container) is sufficient for overcoming friction in the inflow conduit 11, this pressure difference being maintained by the running pump(s) 18 as described above. It will therefore be understood that the pumps do not need to be particularly powerful and energy demanding.

[0060] Power and control equipment required for operating the one or more pumps 18 and the one or more lights 12 are not illustrated, as such equipment is well known in the art. For example, a power module (i.e. solar panel and / or battery) may be provided on the harvesting unit, and the pump(s) 18 may be pre-programmed or remotely controlled. The harvesting assembly can be controlled or configured for harvesting a range of aquatic organisms - simultaneously or separately - and comprises therefore appropriate filter devices to ensure that only organisms within certain size ranges are allowed to enter the cavity 7 and remain in the cavity as water is ejected by the pump(s) 18. To this end, an inflow filter device 31 is arranged in the inflow device 5, for example in the vicinity of the inflow opening 13. Alternatively, an inflow filter device 31’ can be arranged in the first inflow opening 15. An outflow filter device 32 is arranged in the upper region of the cavity 7, upstream of the inlet to the pump(s) 18. The mesh size of the outflow filter device 32 is smaller than the mesh size of the inflow filter device 31; 31’. The filter devices 31 ; 31’, 32 can comprise sieves, nets, or a combination of such, or any other filter device known in the art. The filter devices can be replaceable or / and have an adjustable mesh size. In embodiments, the inflow filter device 31 and the outflow filter device 32 can each comprise multiple filters with different mesh sizes, and / or filters having adjustable mesh sizes. The filter devices can be remotely controlled.

[0061] In the first embodiment of the invention, as described above and illustrated by figures 1-6, the harvesting unit 4 and the inflow device 5 are releasably connected. However, it should be understood that these components can be permanently interconnected, e.g. in the configuration illustrated in figure 4.

[0062] A second embodiment of the invention will now be described with reference to figures 8-11. Unless specified below, the features and functions of this second embodiment shall be deemed to be the same as for the corresponding features and functions of the first embodiment.

[0063] In this second embodiment, an intermediate inflow device 28 is connected to the first inflow opening 15, either releasably as described above, or permanently. The intermediate inflow device 28 can for example be a flexible hose. The inflow device 5 may be of the same kind as in the first embodiment of the invention. Figures 8-10 show the flexible hose 11 in segments; this is to indicate that it may be comprised of several interconnectable segments.

[0064] One advantage of the intermediate inflow device 28 is that the connection to the flexible hose 11 of the inflow device 5 can be performed above the water surface, as shown in figure 9. The upper end of the inflow device 5 is suspended above the water surface while the free end of the intermediate inflow device 28 is connected. Figure 10 shows how the assembly of the inflow device 5 and the intermediate inflow device 28 is lowered into the water.

[0065] In an embodiment, the invented harvesting assembly can be used as a feed pen for fish, for example juvenile cod, as outlined in the following steps: a) Arranging the harvesting assembly at a location suitable for attracting the specified type of fish and starting the one or more pump devices 18;

[0066] b) Configuring the inflow filter device 31 and the outflow filter device 32 for catching and retaining, respectively, fish of a size corresponding to the specified type of fish;

[0067] c) Operating and controlling the one or more light sources 12 to emit light at wavelengths appropriate for attracting the specified type of fish;

[0068] d) When a desired quantity of the specified type of fish has entered the cavity 7, configuring the inflow filter device 31 and the outflow filter device 32 for catching aquatic organisms suitable as feed for the specified type of fish (for example zooplankton);

[0069] e) Operating and controlling the one or more light sources 12 to emit light at wavelengths appropriate for attracting the specified type of aquatic organisms suitable as feed for the specified type of fish.

[0070] Common to all of the embodiments described above is that when the cavity 7 has been filled with a desired amount of aquatic organisms (e.g. zooplankton or juvenile fish), the pump 18 can be deactivated and the outflow conduit 16 can be connected to a facility for storage and transportation, for example a boat or other platform 3 as illustrated in figures 7 and 12. In the illustrated embodiment, the harvesting assembly (i.e. harvesting unit 4 and inflow device 5) is lifted out of the body of water by lifting gear 25 connected to a crane 20 a boat or other platform 3. As the assembly is being lifted out of the water and the pump 18 is inactive, water pressure in the cavity 7 is greater than the water pressure outside the container 1 and the one-way valve 9 is closed, whereby the contents of the cavity 7 is prevented from flowing through the inflow conduit 11.

[0071] Instead, water and harvested aquatic organisms in the cavity 7 flow through the outflow conduit 16 and into the storage and transportation facility. It should be understood that flow through the outflow conduit 16 also may be effected by a pump.

[0072] Although the harvesting unit 4 is described above as an object floating in a body of water and being tethered to the seabed, it should be understood that the harvesting unit may be attached to or be integrated of a vessel such as a boat or barge. In the embodiments described above, various features and details are shown in combination. The fact that several features are described with respect to a particular example should not be construed as implying that those features by necessity have to be included together in all embodiments of the invention. Conversely, features that are described with reference to different embodiments should not be construed as mutually exclusive. As a person skilled in the art readily will understand, embodiments that incorporate any subset of features described herein and that are not expressly interdependent have been contemplated by the inventor and are part of the intended disclosure. However, explicit description of all such embodiments would not contribute to the understanding of the principles of the invention, and consequently some permutations of features have been omitted for the sake of simplicity or brevity.

Claims

Claims1. A harvesting assembly for aquatic organisms, characterized by:- a harvesting unit (4) comprising a container (1) having an internal cavity (7) configured for holding a liquid and aquatic organisms and comprising a first inflow opening (15);- an inflow device (5) having a second inflow opening (13) and a valve device (9) configured for allowing liquid and aquatic organisms to flow through the inflow openings and into the cavity, and wherein at least a portion of the inflow device (5) is arranged in the first inflow opening (15);- an outflow conduit (16) fluidly connected to a lower portion the cavity (7); and - one or more pump devices (18) configured and arranged for discharging water from the cavity.

2. The harvesting assembly of claim 1, wherein the inflow device (5) comprises an elongate conduit (11) having a first interface portion (10) in one end and the second inflow opening (13) at another end, and the first interface portion (10) and a second interface portion (14) in the cavity (7) are configured for mating engagement to form a sealed connection between the harvesting unit (4) and the inflow device (5).

3. The harvesting assembly of claim 2, wherein the first interface portion (10) and the second interface portion (14) are releasable connections.

4. The harvesting assembly of any one of claims 1-3, wherein the harvesting unit (4) comprises one or more buoyancy devices (17) for supporting the harvesting assembly in a body of water (W).

5. The harvesting assembly of any one of claims 1-4, wherein an outflow filter device (32) is provided in the cavity (7) upstream of the one or more pump devices’ (18) inlet, the outflow filter device (32) having a mesh size that prevents aquatic organisms above a desired size to be expelled from the cavity when the harvesting assembly is arranged and in operation in a body of water.

6. The harvesting assembly of any one of claims 1-5, wherein one or more light sources (12) are arranged in the vicinity of the second inflow opening (13) and configured for emitting light that attracts aquatic organisms that are desired to harvest.

7. The harvesting assembly of any one of claims 1-6, wherein the outflow conduit (16) is a flexible conduit and is configured for extending to an upper portion of the harvesting unit (4), above the water surface of a body of water when the harvesting assembly is arranged and in operation in the body of water.

8. The harvesting assembly of any one of claims 1-7, wherein the valve device (9) is a one-way valve, permitting fluid flow only into the cavity (7).

9. The harvesting assembly of any one of claims 2-8, wherein an inflow filter device (31 ; 31’) is arranged in the inflow device (5), in the vicinity of the second inflow opening (13), or in the first inflow opening (15).

10. The harvesting assembly of any one of claims 2-9, wherein an outflow filter device (32) is arranged in the upper region of the cavity (7), upstream of the inlet to the one or more pumps (18).

11. The harvesting assembly of claim 10, wherein a mesh size of the outflow filter device (32) is smaller than a mesh size of the inflow filter device (31 ; 31’).

12. The harvesting assembly of any one of claims 2-11, further comprising an intermediate inflow device (28) releasably or permanently connected to the container (1) lower portion.

13. The harvesting assembly of claim 12, wherein the intermediate inflow device (28) is connected to the first inflow opening (15) and the free end of the intermediate inflow device (28) is configured for releasable connection to the first interface portion (10) of the inflow device (5).

14. A harvesting method for aquatic organisms, by using the harvesting assembly of any one of claims 1-13, characterized by:a) arranging the harvesting assembly in a body of water (W) such that the inflow device (5) extends downwards; andb) operating the one or more pump devices ( 18) to discharge water from the cavity and thus causing water to flow into the cavity (7) via the first inflow opening (15).

15. The harvesting method of claim 14, wherein step a is preceded by:a-2) arranging the harvesting unit (4) floating in the body of water (W); and a-1) arranging at least a portion of the inflow device (5) in the first inflow opening (15).

16. The harvesting method of claim 14 or claim 15, wherein step b is followed by: c) at a desired point in time, discontinue operation of the one or more pump devices; andd) lift the harvesting assembly out from the body of water, whereby the contents of the cavity (7) are allowed to flow through the outflow conduit, by gravity, by a pump system, or a combination.

17. The harvesting method of any one of claims 14-16, wherein lights (12) in the vicinity of the second inflow opening (13) are activated to attract aquatic organisms.

18. The harvesting method of any one of claims 14-16, wherein the harvesting assembly comprises- an outflow filter device (32) provided in the cavity (7) upstream of the one or more pump devices’ (18) inlet, the outflow filter device (32) having a mesh size that prevents aquatic organisms above a desired size to be expelled from the cavity when the harvesting assembly is arranged and in operation in a body of water;- an inflow filter device (31 ; 31 ’) arranged in the inflow device (5), in the vicinity of the second inflow opening (13), or in the first inflow opening (15); and- one or more light sources (12) arranged in the vicinity of the second inflow opening (13) and configured for emitting light that attracts aquatic organisms that are desired to harvest;the harvesting method further comprising the steps of:- configuring the inflow filter device (31) and the outflow filter device (32) for catching and retaining, respectively, fish of a size corresponding to the specified type of fish; - operating and controlling the one or more light sources (12) to emit light at wavelengths appropriate for attracting the specified type of fish;- when a desired quantity of the specified type of fish has entered the cavity (7), configuring the inflow filter device (31) for catching aquatic organisms suitable as feed for the specified type of fish; and- operating and controlling the one or more light sources (12) to emit light atwavelengths appropriate for attracting the specified type of aquatic organisms suitable as feed for the specified type of fish.

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