WO2021059143A2

WO2021059143A2 - Fish management system and method

Info

Publication number: WO2021059143A2
Application number: PCT/IB2020/058862
Authority: WO
Inventors: Nitzan GERZI; Eliezer LIRAZ
Original assignee: Agam Aquaculture Ltd.
Priority date: 2019-09-27
Filing date: 2020-09-23
Publication date: 2021-04-01
Also published as: WO2021059143A3

Abstract

A method of fish management includes using a sorting cage (12) that has sorting barriers (14) and storing barriers (16), and a fish counter (28) positioned relative to the sorting cage (12) for counting fish associated with the sorting cage (12). The sorting barriers (14) open to a first width while the storing barriers (16) are closed. Fish move into the sorting cage (12). The opening of the sorting barriers (14) is adjusted to a second width smaller than the first width, so that fish which are smaller than the second width can leave the sorting cage (12) while fish whose width is larger than the second width cannot swim past the sorting barriers (14). The fish counter counts a current amount of fish located in the sorting cage after an amount of time has passed.

Description

FISH MANAGEMENT SYSTEM AND METHOD FIELD OF THE INVENTION

The present invention generally relates to a system and method for managing the rearing of fish, such as sorting and feeding fish.

BACKGROUND OF THE INVENTION

Collecting, handling, sorting, holding, and transporting fish can have significant effects on fish physiology and survival. Many factors can cause stress to the fish, such as catching fish in a net, removal of the fish from the water for sorting, counting or weighing; water quality (e.g., temperature, dissolved oxygen, ammonia, nitrite, nitrate, salinity, pH, carbon dioxide, alkalinity, hardness and others); competition from juvenile fish for available food; the biomass that the water can support and many other factors. The detrimental effects can be manifested as suppressed immune systems; decreased growth, swimming performance, or reproductive capacity; even death.

Thus a system for growing, sorting and managing fish in a growing pond and the like that minimizes stress to the fish and ensures a healthy biomass environment is clearly needed.

SUMMARY OF THE INVENTION

The present invention seeks to provide a novel and improved system and method for growing, sorting and otherwise managing fish in a growing pond and the like, which minimize stress to the fish and ensure a healthy biomass environment, as described in detail below.

One aspect of the invention relates in general to a sorting process in aquaculture, which can be carried out in oceans, seas, lakes, fish ponds and others, such as for preparing shipment batches within a defined weight range for marketing. In another aspect, the process selectively feeds the fish by size. The fish sorting process can be used to exclude undesired fish birth or juvenile fish, which is a known problem in fish farms.

In one example, fish may be sorted above a given weight (e.g., above 600 g):

1. Attract fish of all sizes to the cage and open barriers to maximum width - fish of all sizes enter

2. Close barriers to width corresponding to given weight - urge fish towards smaller openings, resulting in smaller fish leaving and fish above given weight remain

Sorting to a given weight range (e.g., 500-700 g):

1. Attract fish of all sizes to the cage

Open barriers to width corresponding to 700 g - fish above 700 g cannot enter 2. Close barriers to width corresponding to 500 g - urge fish towards smaller openings, resulting in fish smaller than 500 g leaving and fish in given weight range remain.

There is thus provided in accordance with a non-limiting embodiment of the present invention a method of fish management including using a fish management system that includes a sorting cage that has sorting barriers and storing barriers, each of the sorting barriers and the storing barriers defining a variable passageway, the sorting barriers being barriers between an outside water environment and an inside of the sorting cage and the storing barriers being barriers between the inside of the sorting cage and a storing enclosure, wherein a passageway width of each of the variable passageways is sizable such that fish that have a width greater than the passageway width cannot swim past the passageway width, and a fish counter positioned relative to the sorting cage for counting fish associated with the sorting cage, opening the sorting barriers to a first width while the storing barriers are closed, having fish move from water outside the sorting cage into the sorting cage, adjusting an opening of the sorting barriers to a second width smaller than the first width, so that fish which are smaller than the second width can leave the sorting cage while fish whose width is larger than the second width cannot swim past the sorting barriers, and using the fish counter to count a current amount of fish located in the sorting cage after an amount of time has passed to monitor if the current amount is less than, equal to or greater than a desired amount.

In one aspect, if the current amount is less than the desired amount, then more time is waited and/or the passageway width of the sorting barriers is adjusted until the current amount equals the desired amount, and the fish are expelled from the sorting cage to the storage cage.

In one aspect, if the current amount is greater than the desired amount, then some fish are expelled out of the sorting cage to outside water.

In one aspect, the current amount is used to calculate a feed conversion ratio or biomass of the fish located in the sorting cage.

In one aspect, one or more fish attractors are used to accelerate movement of fish into or out of the sorting cage. The cage may be used just to catch fish, which saves the labor and manpower needed for using traditional nets for catching fish and pulling manually (which stresses the fish), without counting. In one aspect, an expelling element is used to improve exit of fish from the sorting cage. The expelling element may include a wall movable (e.g., translatable or pivotable) towards the storing barriers or the sorting barriers. The expelling element may include a stream of water that flows towards the storing barriers.

The method may further include sensing water quality parameters of water in the sorting cage.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which:

Fig. 1 is a simplified illustration of a fish management system, constructed and operative in accordance with a non-limiting embodiment of the present invention;

Fig. 1A is a simplified illustration of an expelling element used with the fish management system, in accordance with a non-limiting embodiment of the present invention;

Fig. 2 is a simplified block diagram of a fish management method with the system of Fig. 1, in accordance with a non-limiting embodiment of the present invention;

Fig. 3 is a simplified illustration of a fish biomass measurement system, constructed and operative in accordance with a non-limiting embodiment of the present invention; and

Figs. 4A-4D are simplified illustrations of a user interface of the fish biomass measurement system.

DETAIFED DESCRIPTION OF EMBODIMENTS

Reference is now made to Fig. 1, which illustrates a fish management system 10, constructed and operative in accordance with a non-limiting embodiment of the present invention.

Fish management system 10 may include a sorting cage 12 (preferably but not necessarily made of rigid materials), which includes sorting barriers 14 and storing barriers 16. The sorting barriers 14 and the storing barriers 16 may include bars, rods, slats, shutters and the like which are movable to create a variable passageway 18 or 20, respectively between adjacent sorting barriers 14 or storing barriers 16. For example, the barriers 14 or 16 may be rotatable about a pivot, which creates the variable passageway 18 or 20; alternatively, the barriers 14 or 16 may be movable along a channel or groove, which creates the variable passageway 18 or 20. The cage 12 may be provided with legs for anchoring the cage in the water, such as in shallow water. Alternatively, cage 12 may be a floating cage, particularly useful in deep water. The cage may be provided with floats, whose position may be adjusted to adjust the depth that the cage floats in the water.

The sorting barriers 14 are the barriers between the water environment outside the cage 12 and the inside of the cage. The storing barriers 16 are the barriers between the inside of the cage 12 and a storing area or enclosure 22, which may be rigid or flexible (such as netting). The storing area or enclosure 22 may be attached to cage 12 with quick- disconnect connectors. For easy transportation of the cage, cage 12 may be provided with lifting ears, quick-disconnect electrical, communications and/or mechanical connectors, and all cables and wires may be insulated and sealed to be waterproof (or watertight) in accordance with appropriate regulations.

The passageway width may be selected such that fish that have a width greater than the passageway width cannot swim past the barriers. It is known in the art that the width of the fish is related to its weight. As one example, one may reference the article “Sorting and Grading Warmwater Fish”, by Kelly and Heikes, SRAC Publication 391, March 2013. Tables 8 and 9 from that publication are examples:

Accordingly, the passageway width may be selected for the particular fish species and desired weight range. The fish management system 10 may include one or more fish attractors 24, such as but not limited to dry or liquid food, oxygen, water flow, sounds and others, to attract fish and urge them to swim either into the sorting cage 12 or out of the sorting cage 12. (In one non-limiting example of carrying out the invention, the sound of a feeding machine has been surprisingly found to attract the fish to the area where the food is to be distributed even before the food is actually dispensed.) As such, the one or more fish attractors 24 may be positioned inside the cage 12 or at a distance outside of the cage 12. For example, in the illustrated embodiment, the fish attractor 24 may include piping with an inlet 1 at the top of the cage 12, an inlet 2 near the sorting barriers 14.

Structure may be provided for preventing food from floating or flowing out of the borders of the cage 12, such as but not limited to, netting placed on top of the water around the perimeter of the cage that blocks the food from flowing past the netting.

In another embodiment, the sorting cage may be colored with colors that either attract the fish or at least are not perceived by the fish to be suspicious. The inventor has noticed that shades of green are perceived as a friendly color and the fish are more amenable to entering past the sorting barriers into the cage. On the other hand, shiny metal colors may be perceived as suspicious, and it will take more time for the fish to acclimate to the situation and be persuaded to enter the sorting cage.

It has been surprisingly found that placing the sorting cage in the water zone meant for breeding the fish before the fish are introduced to that breeding zone, reduces or completely eliminates the time normally needed for fish to acclimate to the cage and allow themselves to enter the cage. By placing the cage in the water before the fish, the fish are not suspicious and readily enter the cage almost immediately.

The fish management system 10 may include an expelling element 26 inside cage 12 that accelerates or improves the exit of fish from the cage 12. The expelling element 26 may move horizontally, vertically or in other directions and in any combination of directions. (Vertical movement may help expel fish caught in a wall of the cage.) For example, without limitation, the expelling element 26 may be a movable wall that slowly moves towards the direction of the storing barriers 16. As another example, expelling element 26 may be a stream of water that flows towards the direction of the storing barriers 16. As yet another example, expelling element 26 may be a heating or cooling element that either heats or cools the water to cause the fish to seek water outside the cage that has a temperature that better suits them. Reference is now made to Fig. 1A, which illustrates another version of a two-way expelling element. In this embodiment, the expelling element 26 includes a wall that extends over the bottom of the sorting cage 12. The wall has a first end 17 near or at the sorting barriers 14 and a second end 19, opposite to the first end 17, near or at the storing barriers 16. The expelling element 26 can pivot about first end 17 and can also pivot about the second end 19. An actuator 23 is operatively coupled to the expelling element 26 for selectively pivoting the expelling element 26 about the first end 17 or the second end 19. In this manner, the expelling element 26 can expel fish out of the sorting cage 12 in any desired direction.

The fish management system 10 may include an underwater fish counter 28 positioned relative to storing cage 12 (e.g., inside or outside the cage). Many different kinds of fish counting sensors and systems are described in the prior art and can be used in the present invention. One example of a fish counting system is described in US Patent 5692064, in which fish are counted by emitting an ultrasonic wave or an electromagnetic wave toward a predetermined area of a body of water where fish pass (e.g., a fish farming pool, a river or the like). Reflected waves are received from the fish bodies so that the reflected waves received from a cross section of the predetermined area are periodically stored. An ultrasonic wave fish shade image is produced that shows changes of fish shades. Fish are counted by performing an image processing which discriminates the ultrasonic wave fish shade image based on a predetermined fish shade decision rule. This arrangement reduces errors that arise due to muddiness and dust in the water and allows an automatic continuous fish counting ability over a long time period. Other systems are described, for example, in published US Patent Application 20180263223 and European Patent Application 3316220. The latter describes a method for determining the biomass of tuna in a region of water with an acoustic sensor and submerged image capture means.

Fish counting is used in the present invention for various purposes, such as to determine the exact amount of fish in a batch to be sold, calculating the average weight of fish (biomass), or to calculate feed conversion ratio (FCR) and others.

Biomass is the number of fish in a farm population, multiplied by their individual weight.

The FCR is the amount of feed it takes to grow a given weight (e.g., kilogram) of fish. For example, if it requires two kilograms of feed to grow one kilogram of fish, the FCR is two. Stated in another way, FCR is the weight of the feed given to the fish divided by the weight gain of the fish. If a feed has a low FCR, it takes less feed to produce one kilogram of fish then it would if the FCR were higher. A low FCR is a good indication of a high quality feed.

A controller (processor) 30 and power supply 32 may be in communication with the various components of the system 10.

The fish management system 10 may include one or more water property sensors 34 for sensing water quality parameters, such as but not limited to, temperature, dissolved oxygen, ammonia, nitrite, nitrate, salinity, pH, carbon dioxide, alkalinity, hardness and others. These sensed properties may be used to manage the biomass of the system and the well-being of the fish.

The following are non-limiting examples of methods of managing fish growth and selection in accordance with an embodiment of the invention.

In one method, as shown in the block diagram of Fig. 2, the fish are to be sorted to a desired minimum size or weight. In step 101, the sorting barriers are opened to a first given spacing X (which may be a maximum spacing for fish that are to be sorted to a desired minimum size or weight), while the storing barriers are closed. In step 102, the fish attractors are employed to attract fish into the sorting cage. In step 103 (which may take place at any time in the method), the fish counting system is used to count the amount of fish in the sorting cage and to monitor the biomass of the system (optionally using the water property sensors).

In step 104, after the fish have fed on the food for a desired time, the sorting barriers can either remain at the first width (in which case all the fish remaining in the sorting cage have a width not less than the first given spacing X), or can optionally be opened to another width (different from width X), based on width/weight ratio of the particular fish species, so that the smaller fish can leave and swim back to the fish pond while larger fish cannot swim past the sorting barriers. A more detailed example of opening to another width is given in step 204.

In step 105, the storing barriers are opened to let fish swim from the sorting cage to the storage cage. In step 106, the fish attractors may be employed to attract the fish into the storage cage. Optionally, the expelling element may be used to accelerate the flow of fish out of the sorting cage into the storage cage. In step 107, a fish counter located between the two cages counts the fish crossing to the storage cage. As the total order quota of fish weight meets the required number, which may require a repetition of a few cycles, the storing barriers are closed. In another method, the fish are to be sorted to a desired size or weight range. In such as case, instead of step 104, step 204 is used. In step 204, the sorting barriers are opened to a second width Y (smaller than the first width, that is, Y<X) so that the smaller fish can leave and swim back to the fish pond while larger fish (between Y and X) cannot swim past the sorting barriers. In this manner, the invention can be used to obtain segmentation of batches of fish. For example, one can obtain one batch of fish in the 200- 400 g range, another batch in the 400-500 g range and yet another in the 500-700 g range, and of course other ranges.

In steps 205-209, the invention is used to monitor how many fish are currently in the sorting cage and to determine how many more fish are needed to achieve a desired quantity of fish in a batch.

In one non-limiting example, an order is made for a batch of an amount M fish in the Y-X range. Step 204 is carried out and the fish counter is used to count the fish located in the sorting cage after time T has passed since initiating step 204 (step 205). (Time T may be predetermined or selected in real time.) In this manner, the fish counter senses and monitors the amount N of fish that are currently present in the sorting cage. If N<M, then more time is waited and/or step 204 is carried out again to adjust the passageway width of the sorting barriers until N=M (step 206). The batch is then expelled to the storage cage for shipping or processing (step 207). If N>M, then the expelling element can expel fish to the outside water until N=M (step 208).

Thus the invention can be used for selective feeding to obtain fish in a range of weights and to improve biomass.

In all the variations of the methods of the invention, the controller can use previous data of the rate of the fish entering or exiting the cage and use this time rate data to close or open the barriers a certain time before achieving a desired goal so as not to go beyond the goal (a predictive mode of operation). For example, a desired goal is to have 1000 kg of fish in the sorting cage of a certain size (e.g., this is the purchase order for fish). The controller that monitors the fish senses that currently there are 900 kg of fish, meaning 100 kg of fish are still needed to enter the cage to reach the goal. If the controller closes the barriers only after sensing that an additional 100 kg of fish have entered the cage, by the time the barriers close more fish will have entered, which means there are too many fish (overshooting the goal is a loss to the fish breeder). In one aspect of the invention, the controller can use the rate data to prevent going beyond the desired goal. If the fish enter the cage at the rate of 100 fish per minute and each fish is 1 kg and it takes one minute for the barriers to close, then the controller can close the barriers as soon as the count reaches 900, because in the one minute it takes the barriers to close, 100 kg of fish will enter the cage and there is no overshooting the goal.

The invention can also be used to expel juvenile fish, which can be a problem in rearing fish of a desired weight. Juvenile fish include fry (recently hatched fish that can actively feed for itself) and fingerlings (fish that has reached the stage where the fins can be extended and where scales have started developing throughout the body). Juvenile fish can eat fish food meant for bigger fish and emit ammonia which is bad for the other fish. By letting the juvenile fish swim past the sorting barriers, the sorting cage is freed of the juvenile fish which improves breeding conditions for the desired fish and improves biomass and FCR.

The invention can also be used to constantly monitor FCR, such as for monitoring sicknesses (sick fish do not grow at the normal rate). The system does not create any stress to the fish. In step 108, the biomass is measured at a first time and measured again and compared to monitor the progress of the biomass and calculate FCR. The feed may be changed in accordance with the calculated FCR to improve (lower) the FCR.

As mentioned above, biomass is the number of fish multiplied by their individual weight. The biomass may be calculated by segmenting the fish into different weight ranges: after all fish enter the sorting cage, the fish are urged to leave in stages by controlling the opening of the barriers, each stage comprising a different weight range, and the number of fish in each stage is counted. In this manner, the average weight of the fish can be calculated. The average weight multiplied by the total number of fish is the biomass.

In another method, the signal strength of the fish counter is a function of the average size/weight of the fish. After monitoring the signal strengths of the fish counter over time, one can determine a correlation between the signal strength and the fish weight.

Accordingly, average fish weight can be determined without segmentation by using this correlation to determine average fish weight of all fish that have passed by the fish sensor of the fish counter. The direction of the fish swim (into the cage as opposed to out of the cage) can easily be determined, such as by placing more than one sensor along a path and taking into consideration at what time the first sensor in the path sensed a fish as opposed to the time the second sensor in the path sensed the fish. In a closed loop system, the control system 30 of the cage system (or a controller 54 of a fish biomass measurement system described below) gets a continuously-sensed number of fish entering the cage per time unit. If the intensity of fish entering is less than that of a previous time period, then the feeder may be instructed to stop feeding. If sensor parameters are within the standard range and nevertheless fish do not rush to eat, an alarm may be sent to the fish farmer, providing an indication of a problem, such as disease, disturbance, etc. If sensor parameters are out of a standard range (e.g., above or under limits), then again an alarm may be sent to the fish farmer.

Reference is now made to Fig. 3, which illustrates a fish biomass measurement system (continuous real-time measurement), constructed and operative in accordance with a non-limiting embodiment of the present invention.

The fish biomass measurement system may include a floating platform 52 upon which (or inside of which) is mounted a control unit 54, such as an electronic and power box that includes without limitation a power supply (optionally, solar panels), electronics board, transmission unit and other modules. The floating platform 52 may have a carrying handle 56. The system may include a communications unit 58, such as but not limited to, a cloud/ smartphone communication unit (e.g., 3D/BLE/WiFi).

The system may also include a propelling element 60, such as remote-controlled motors, and a water quality sensing unit 62, such as for sensing oxygen, temperature, pH, ammonia and other parameters.

A sensing unit 64 may extend down from floating platform 52. The sensing unit has walls spaced from one another by a space through which the fish can swim past one or more fish counting sensors 66.

Figs. 4A-4D illustrate a user interface 68 of the fish biomass measurement system, and show different data that can be displayed to the user.

The fish biomass measurement system is used as follows. Fish swim past the fish counting sensors 66 and the sensors 66 sends signals to control unit 54.

The control unit 54 calculates the total number of fish passing through the system and the intensity (quantity per time) of fish swimming past (such as swimming past the system into the sorting cage, if the system is placed near the cage).

In a closed loop system, the controller 54 gets a continuously-sensed number of fish entering the cage per time unit. If the intensity of fish entering is less than that of a previous time period, then the feeder may be instructed to stop feeding. If sensor parameters are within the standard range and nevertheless fish do not rush to eat, an alarm may be sent to the fish farmer, providing an indication of a problem, such as disease, disturbance, etc. If sensor parameters are out of a standard range (e.g., above or under limits), then again an alarm may be sent to the fish farmer. The fish biomass measurement system may have an attractor, such as a feeder which attracts fish to pass close to the sensors, such as any of the attractors mentioned above with the cage system.

Claims

What is claimed is:

1. A method of fish management comprising: using a fish management system that comprises a sorting cage (12) that has sorting barriers (14) and storing barriers (16), each of said sorting barriers (14) and said storing barriers (16) defining a variable passageway (18, 20), said sorting barriers (14) being barriers between an outside water environment and an inside of said sorting cage (12) and said storing barriers (16) being barriers between the inside of said sorting cage (12) and a storing enclosure (22), wherein a passageway width of each of said variable passageways (18, 20) is sizable such that fish that have a width greater than said passageway width cannot swim past said passageway width; and a fish counter (28) positioned relative to said sorting cage (12) for counting fish associated with said sorting cage (12); opening said sorting barriers (14) to a first width while the storing barriers (16) are closed; having fish move from water outside said sorting cage (12) into said sorting cage

(12); adjusting an opening of said sorting barriers (14) to a second width smaller than the first width, so that fish which arc smaller than the second width can leave said sorting cage (12) while fish whose width is larger than the second width cannot swim past said sorting barriers (14); and using said fish counter (28) to count a current amount of fish located in said sorting cage (12) after an amount of time has passed to monitor if the current amount is less than, equal to or greater than a desired amount.

2. The method according to claim 1, wherein if the current amount is different than the desired amount, then more time is waited and/or the passageway width of said sorting barriers (14) is adjusted until the current amount equals the desired amount.

3. The method according to claim 1, further comprising expelling the fish from said sorting cage (12) to said storing enclosure (22).

4. The method according to claim 1, wherein adjusting said opening of said sorting barriers (14) is used to cause fish having at least a desired weight to remain in said sorting cage (12) and fish below said desired weight to be outside said sorting cage (12).

5. The method according to claim 1, wherein adjusting said opening of said sorting barriers (14) is used to cause fish of a desired weight range to remain in said sorting cage (12) and fish not in said desired weight range to be outside said sorting cage (12).

6. The method according to claim 1, comprising using the current amount to calculate a feed conversion ratio or biomass of the fish located in said sorting cage (12).

5. The method according to claim 1, comprising using one or more fish attractors (24) to accelerate movement of fish into or out of said sorting cage (12).

6. The method according to claim 1, further comprising using an expelling element (26) to improve exit of fish from said sorting cage (12).

7. The method according to claim 6, wherein said expelling element (26) comprises a wall movable towards said storing barriers (14) or said sorting barriers (16).

8. The method according to claim 6, wherein said expelling element (26) comprises a stream of water that flows towards said storing barriers (14).

9. The method according to claim 1, further comprising sensing water quality parameters of water in said sorting cage (12).

10. A device for managing fish comprising: a cage (12) comprising sorting barriers (14) and storing barriers (16), each of said sorting barriers (14) and said storing barriers (16) defining a variable passageway (18, 20); and a two-way expelling element (26) having a first operative configuration to urge fish inside said cage (12) towards said sorting barriers (14) and a second operative configuration to urge fish inside said cage (12) towards said storing barriers (16).

11. The device according to claim 10, wherein said expelling element (26) comprises a wall that has a first end (17) near or at said sorting barriers (14) and a second end (19), opposite to said first end (17), near or at said storing barriers (16), wherein said expelling element (26) is pivotable about said first end (17) and said second end (19).

12. The device according to claim 11, comprising an actuator (23) operatively coupled to said expelling element (26) for selectively pivoting said expelling element (26) about said first end (17) or said second end (19).

13. A fish biomass measurement system comprising: a floating platform (52) comprising a control unit (54) and a communications unit

(58); a sensing unit (64) that extends down from said floating platform (52), said sensing unit (64) comprising walls spaced from one another by a space through which fish can swim past, wherein one or more fish counting sensors (66) are coupled to at least one of said walls; and a propelling element (60) coupled to said floating platform (52).

14. The fish biomass measurement system according to claim 13, further comprising an attractor that attracts fish to pass close to said fish counting sensors (66).

15. The fish biomass measurement system according to claim 13, further comprising a water quality sensing unit (62) for sensing at least one of oxygen, temperature, pH, or ammonia.