NO20210823A1

NO20210823A1 - Sorting arrangement for fish

Info

Publication number: NO20210823A1
Application number: NO20210823A
Authority: NO
Inventors: Robin Mek Halsebakk
Original assignee: Soelvtrans As
Priority date: 2021-06-25
Filing date: 2021-06-25
Publication date: 2022-12-27

Description

SORTING ARRANGEMENT FOR FISH

Technical Field

[0001] The present invention relates to a sorting arrangement for fish, in particular for smolt.

Background Art

[0002] Both in fish farming and fishery it is important to be able to efficiently sort fish into different sizes. In fish farming, it is a desire to transfer larger fish, i.e. above a certain size to a net pen where they can grow to a size ready for slaughter, while the smaller may be collected in separate breeding tanks for further growth before they are transferred to a net pen.

[0003] In fishery, there are many places restrictions on how small fish that may be caught. This is primarily adjusted by the mesh size of the nets and the sorting grid, but nevertheless some fish that are below the minimum size are still caught. These fish should preferably be sorted out and returned to the sea while alive.

[0004] Sometimes it is also desired to return fish above a certain size to the sea, such as in shrimp fishing.

[0005] There are known sorting arrangements for fish. One example is shown in CN204579505U, which shows a sorting grid comprising a set of bars having two different diameters and thereby different distances between the bars. The fish slides down an inclined table to the first end of the bars, having a larger diameter. Here the smallest fish fall between the bars. Then the remaining fish reach the end of the bars having a smaller diameter, where the next sizes fish will fall between the bars. The largest fish will pass along the bars without falling between. Consequently, this arrangement can sort fish into three different sizes.

[0006] Other sorting arrangements are known from BR102013016291B1, EP1212940A1 and NO345372B1.

[0007] A major problem with existing sorting arrangements is that if fish do not always arrive evenly at the sorting grid, but in smaller or larger batches, the larger fish will prevent the smaller fish from falling between the sorting bars. The smaller fish will slide on top of the larger fish without coming in sufficient contact with the bars. Consequently, a proportion of smaller fish will end up together with the larger fish. However, fish grow better if the standard deviation of the fish size is low.

A main purpose for the sorting of fish farming according to the invention is thus to lower the standard deviation from a mean value of the fish size in terms of fish groups. After smolt is transported from onshore plant to sea sites, all fish will be put into sea. This will be performed by separating the sizes of the fish into different pens.

[0008] Another purpose of the invention to reduce the time the fish spend out of their natural habitat, water as much as possible to increase the fish welfare.

[0009] The batchwise distribution of fish also create problems at the fish counter, which are often found downstream of the sorting grid. If several fish enter the counter simultaneously, the counting may not be correct. Several fish may be counted as one fish, and the total number may deviate substantially from the true number.

[0010] As the fish count is used as a basis for calculating the price of the load of fish, the seller may be paid less than he should. Oppositely, the buyer will pay for a proportion of small fish that he did not wish to receive. The counting is further beneficial for knowing the number of fish size and biomass at every stage in the system. This is relevant both for the loading of fish into the system to avoid overload, and for the loading of fish into the different pens to know how many fishes that have been put out into the sea in the different pens.

[0011] It is further beneficial to arrange the system inhouse to avoid the risk of winter wound. The cold weather may damage the fish if the system is not placed indoor. A fish that is arranged out of water is particularly vulnerable to the outside temperature in the surrounding

[0012] It is therefore a desire to avoid or at least minimize these sorting and counting problems.

Summary of invention

[0013] The primary objective of the present invention is to ensure an even distribution of fish across both the width and length of the sorting grid.

[0014] It is an additional objective of the present invention to ensure that fish arrives more evenly at the fish counter, preferably separated into single fish.

[0015] The above objectives are met by the invention according to the subsequent claims.

Brief description of drawings

[0016] The invention will now be described on more detail, referring to the enclosed drawings, which shows a preferred embodiment of the invention, in which:

Figure 1 shows a sorting arrangement according to the invention in isometric view from a first direction,

Figure 2 shows the sorting arrangement of figure 1 in isometric view from a second opposite direction, and

Figure 3 shows the sorting arrangement of figure 1 in planar view.

Detailed description of the invention

[0017] The sorting arrangement is particularly designed for placement on board a boat, such as a service boat or a fishing vessel. It may however also be placed on a raft or on shore. It may be a preferred option to place the system inhouse to shield the fish from low temperatures outdoors. However, the invention is not limited to such inhouse placement of the system.

[0018] Referring to all the figures collectively, they show an embodiment of a sorting arrangement according to the invention. From an upstream end to a downstream end it comprises the following main components:

• An inlet 1 for fish and water.

• A separation grating 2.

• An overflow bin 3

• A moveable bottom screen 4 in said overflow bin 3.

• An overflow edge 5.

• A sorting station 6

• Fish counters 7.

• Fish transport lines 8.

[0019] The inlet 1 may be coupled to a fish pump (not shown) that pump fish and water either directly from the sea, such as from a pen or breeding tank, or from a receiving tank (not shown). The pump creates a flow of fish and water that flows upward from the inlet. Alternatively, the fish is fed into the arrangement from a higher altitude by gravity. At each side of the inlet is a separation grating 2 that is inclined downwards in the downstream direction. The fish and water flow sideways over the upstream edge 11 of each grating 2. At the grating 2 the water is separated from the fish. The water is conducted back to the sea, pen or breeding tank while the fish slides down a chute 12 to the overflow bin 2.

[0020] The overflow bin 2 is filled with water and a separate pump (not shown) pumps new water into the bin 2 from the bottom.

[0021] The overflow bin 2 has one wall 13 that has a lower height and three walls 14, 15, 16 with a higher height. The lower wall 13 joins the overflow edge 5.

[0022] Fish and water in the overflow bin 3 will flow over the overflow edge 5 and across a table 17. Downstream of the table 17 is the sorting station 6. This comprises a first set of sorting bars 18. The sorting bars 18 are preferably rotatable and the distance between the bars can be adjusted to a first gap between the bars 18, to allow fish below a certain size to fall between the bars 18.

[0023] Downstream of the first set of sorting bars 18 is a second set of sorting bars 19. These may be identical to the first set of sorting bars 18 but are adjusted to have a larger gap between the bars 19, which will allow fish that have an intermediate size to fall between the bars 19.

[0024] The bars 18, 19 of the sorting station are oriented in the conveying direction of the fish. To reduce the time out of the water for the fish, the sorting station 6 is preferable arranged shorter in the transport direction than the width of the sorting station 6. This provides an equal distribution with low pace over the short but wide sorting station 6.

[0025] Downstream of the second set of bars 19 is the counting station 7. The counting station has lower counters 20 and upper counters 21. Fish that has fallen through the second set of sorting bars 19 are conveyed to the lower counters 20 and fish that has passed over both sets of sorting bars 18, 19 are conveyed to the upper counters.

[0026] The fish that falls between the first set of bars 18 are considered underdeveloped or rejects. This fish will be conveyed to destruction.

[0027] The fish is sorted into two different size ranges by the sorting station 6. The two size ranges will be put out in two different pens. Hence the fish that have been sent through the lower counters 20 will be transported to a pen for the smaller size range, while the fish sent to the upper counters 21 will be transported to a pen for the larger size range.

[0028] This smaller size range fish is conveyed through a right-hand branch of the transport pipelines 8 and the larger size range fish will be conveyed through a lefthand branch of the transport pipelines 8. The transport pipelines 8 are full of fresh transport water that has been led into the transport pipelines to facilitate the transport of the fish.

[0029] As the fish will arrive at the inlet in an intermittent flow, it is necessary to even out the flow if fish. This is done by the overflow bins 2. The pumps pumping water into the overflow bins 3 ensures a constant flow over the overflow edge 5. The flow is also evenly distributed along the length of the edge 5. Consequently, there will be a virtually constant supply of fish to the sorting station 6.

[0030] Occasionally, the inflow of fish through the inlet 1 may be substantially reduced or completely stop. In that case the moveable bottom screen 4 of the overflow bins 3 will be moved upwards to force the fish in the overflow bin 2 upwards to the overflow edge 5. This will ensure that the sorting station receives fish that is still in the overflow bin 3 while awaiting further ingress of fish through the inlet 1. When the ingress of fish increases beyond the capacity of the sorting station 6, the bottom screen 4 will again be lowered to accommodate for the new fish.

[0031] When all fish has been received by the arrangement and have arrived in the overflow bin 3, the bottom screen 4 will also be gradually raised to press the fish up to the overflow edge 5. The bottom screen will be raised until all fish has left the overflow bin 3.

[0032] The flow of fish over the overflow edge 5 can also be adjusted by adjusting the pump rate of the pumps pumping water into the overflow bin 5.

The flow of fish over the overflow edge 5 may also be adjusted by introducing an air into the bottom of overflow bin 5, creating an upstream flow of air bubbles lifting fish up.

[0033] The bottom screen 4 can be raised vertically or be swung about an axis, such as being hinged to the wall 16 and moved from a position approximately parallel with the wall 16 to an approximately horizontal position.

[0034] The left- and right-hand sides of the sorting arrangement are in principle identical. It is therefore possible to use only one side if there is a need for a reduced capacity.

Claims

1. A sorting arrangement for fish, comprising an inlet and a sorting station, characterised in that an overflow bin is arranged downstream of said inlet and upstream of said sorting station, said overflow bin having a variable space for said fish and an adjustment mechanism to adjust said variable space in order to create an even flow of fish towards said sorting station.

2. The sorting arrangement of claim 1, characterised in that it comprises an overflow edge at the downstream side of said overflow bin.

3. The sorting arrangement of claim 2, characterised in that said overflow bin has walls extending above said overflow edge except for adjacent said overflow edge.

4. The sorting arrangement of any of the preceding claims, characterised in that it comprises a moveable screen to adjust the variable space,

5. The sorting arrangement of claim 4, characterised in that the movable screen is a moveable bottom.

6. The sorting arrangement of any of the preceding claims, characterised in that it comprises a pump to pump water into said overflow bin.

7. The sorting arrangement according to any of the preceding claims, characterised in that the flow fish over the overflow edge is adapted to be adjusted by adjusting a pump rate of one or more pumps pumping water into the overflow bin, or introducing air into the bottom of the overflow bin, to create an upstream flow of air bubbles lifting fish up.

8. The sorting arrangement of any of the preceding claims, characterised in that at least one separation grating is arranged downstream of said inlet and upstream of said overflow bin.

9. The sorting arrangement of claim 7, characterised in that said inlet is directed upwards between two separation gratings.

10. The sorting arrangement of any of the preceding claims, characterised in that said sorting station has at least an upstream and a downstream set of sorting bars, said sets of sorting bars having adjustable gaps between the bars.

11. The sorting arrangement of claim 9, characterised in that fish counters are arranged downstream of said sorting station, and that the counters comprises a first set of counters that are arranged to receive fish that has passed over two sets of sorting bars, and a second set of sorting bars that are arranged to receive fish that has fallen through the downstream set of sorting bars.