A three-layer multi-mesh composite gillnet device for investigating reservoir fish resources

Abstract

The invention discloses a three-layer multi-mesh composite gill net device for investigating fish resources in a reservoir. The device comprises a floating net for capturing upper layer fish and a sinking net for capturing bottom layer fish. The floating net is located above the sinking net. Both the floating net and the sinking net comprise multi-layer nets. The top of the multi-layer net is connected with a plurality of foam floats through an upper line, and the bottom of the multi-layer net is connected with a plurality of lead sinkers through a lower line. The multi-layer net comprises two oppositely arranged outer nets, an inner net is arranged between the two outer nets, the mesh size of the outer net is twice the mesh size of the inner net, the inner net and the outer net are respectively composed of 12 fishing nets with different mesh sizes and are connected by a zipper. The invention can realize the use of the three-layer multi-mesh composite gill net, with better fishing effect and higher fishing efficiency. On the one hand, the efficiency of fish investigation can be improved. On the other hand, a large amount of time for arranging nets and picking up fish catches can be saved, operation efficiency can be improved, and the purpose of partial repair can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of reservoir fish resource investigation, in particular to a three-layer multi-mesh composite gill net device for investigating reservoir fish resources. Background Art

[0002] Fish are an important part of my country's reservoir ecosystem. They are diverse in species, have a wide range of diets, and are rich in resources. They play a very important role in the energy transfer and material circulation of the reservoir food web. The investigation of the structure and resource quantity of reservoir fish communities is the basis for fishery capture and stocking management and reservoir ecosystem health assessment. Survey sampling is the difficulty and key to assessing reservoir fish resources. Appropriate sampling devices need to be selected for different reservoir habitats and survey objects.

[0003] Gillnet sampling is widely used in reservoir fish resource surveys due to its simple operation and high efficiency. Most of the gillnets commonly used in fish resource surveys are made or improved based on European standards (BSI Standards Publication). They are generally made of single-layer nets and are widely used in fish resource surveys and research in various countries around the world. However, due to the differences in individual size, body shape and swimming ability among different populations in fish communities, and the large water depth of reservoirs, single-layer multi-mesh composite gillnets are not effective in catching large fish individuals. They often capture a higher proportion of small fish populations or small fish, and small fish dominate the catch, which is inconsistent with the actual situation of fish communities. In addition, single-layer multi-mesh composite gillnets are easy to break, have high cost of use, and are cumbersome and easy to break when picking up the catch. After the mesh is damaged, the entire composite gillnet is difficult to reuse, which is easy to cause waste and affect the fishing efficiency. Therefore, it is necessary to innovate single-layer multi-mesh gillnets to improve the efficiency of fish surveys on the one hand, and improve the operation efficiency and resource utilization efficiency by achieving local repairs on the other hand. Summary of the invention

[0004] The purpose of the present invention is to provide a three-layer multi-mesh composite gill net device for investigating fish resources in a reservoir, so as to solve the problems existing in the above-mentioned prior art and realize the use of a three-layer multi-mesh composite gill net. The three-layer multi-mesh composite gill net has better fishing effect and higher fishing efficiency by adding special nets, changing the mesh size and combination method and the net connection method. On the one hand, it can improve the efficiency of fish investigation, and on the other hand, it can save a lot of time in arranging nets and picking up catches, improve operating efficiency, and achieve the purpose of local repair.

[0005] To achieve the above-mentioned purpose, the present invention provides the following scheme: The present invention provides a three-layer multi-mesh composite gillnet device for investigating fish resources in a reservoir, comprising a floating net for capturing upper-layer fish and a sinking net for capturing bottom-layer fish, wherein the floating net is located above the sinking net, and the floating net and the sinking net both comprise multi-layer nets, wherein the top of the multi-layer net is connected to a plurality of foam floats through an upper line, and the bottom of the multi-layer net is connected to a plurality of lead sinkers through a lower line;

[0006] The multi-layer net includes two outer nets arranged opposite to each other, an inner net is arranged between the two outer nets, the tops of the two outer nets are connected to the top of the inner net by an upper line and are wound on a foam float, and the bottoms of the two outer nets are connected to the bottom of the inner net by a lower line;

[0007] The inner net garment comprises a plurality of detachably connected first single-layer net sheets, and the outer net garment comprises a plurality of detachably connected second single-layer net sheets.

[0008] Preferably, the number of the first single-layer mesh sheets is 12, the mesh sizes of the 12 first single-layer mesh sheets are all different, the mesh size of the first single-layer mesh sheets is a first value, and the first value range is 5mm to 55mm.

[0009] Preferably, the number of the second single-layer mesh sheets is 12, and two of the second single-layer mesh sheets are arranged corresponding to the first single-layer mesh sheet. The mesh size of the second single-layer mesh sheet is a second value, and the second value is twice the first value.

[0010] Preferably, any one of the first single-layer meshes with different mesh sizes is detachably connected to an adjacent one of the first single-layer meshes via a zipper, and any one of the second single-layer meshes is detachably connected to an adjacent one of the second single-layer meshes via the zipper.

[0011] Preferably, the gravity of the lead sinker on the floating net is smaller than the buoyancy of the foam float on the floating net, and the gravity of the lead sinker on the sinking net is greater than the buoyancy of the foam float on the floating net.

[0012] Preferably, a through hole is opened at the center of the foam float, the upper line wire passes through the through hole, and the upper line wire is slidably connected to the foam float, and a through groove is opened in the foam float, and the through groove is connected to the through hole.

[0013] Preferably, the upper rail and the lower rail are both made of polyethylene.

[0014] Preferably, the distance between a plurality of the foam floats is 20 cm, and the distance between a plurality of the lead sinkers is 20 cm.

[0015] The present invention discloses the following technical effects:

[0016] 1. By setting the floating net and the sinking net as multi-layer nets, the multi-layer nets have strong entanglement and wrapping functions for both large and small fish. The setting of multi-layer nets makes fishing more efficient, the species and size of the catch are richer, and it can more accurately reflect the real species composition, individual size, density and biomass characteristics of the reservoir fish resources.

[0017] 2. The foam float is designed to save a lot of time in arranging nets and picking up catches, thereby improving the efficiency of fish investigation.

[0018] 3. A plurality of first single-layer meshes are detachably connected, and a plurality of second single-layer meshes are detachably connected. When a first single-layer mesh or a second single-layer mesh is damaged, the first single-layer mesh or the second single-layer mesh can be replaced to achieve the purpose of local repair, thereby increasing the service life of the fishing net and reducing the cost of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] Figure 1 It is a schematic diagram of the main structure of the floating net and the sinking net;

[0021] Figure 2 It is a schematic diagram of the structure of the inner mesh garment;

[0022] Figure 3 It is a schematic diagram of the mesh inner diameter structure;

[0023] Figure 4 It is a schematic diagram of the connection relationship between the foam float and the moving rope;

[0024] Figure 5 A schematic diagram of the entanglement state of fishing;

[0025] Among them, 1- foam float, 2- lead sinker, 3- upper line, 4- lower line, 5- first single-layer mesh, 6- second single-layer mesh, 7- zipper, 8- through hole, 9- through groove, 10- floating net, 11- sinking net. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] The present invention provides a three-layer multi-mesh composite gill net device for investigating fish resources in a reservoir, comprising a floating net 10 for capturing upper layer fish and a sinking net 11 for capturing bottom layer fish, the floating net 10 is located above the sinking net 11, both the floating net 10 and the sinking net 11 comprise multi-layer nets, the top of the multi-layer nets are connected with a plurality of foam floats 1 through an upper line 3, and the bottom of the multi-layer nets are connected with a plurality of lead sinkers 2 through a lower line 4; the multi-layer nets comprise two oppositely arranged outer nets, an inner net is arranged between the two outer nets, the tops of the two outer nets are connected with the top of the inner net through an upper line 3 and are wound around the foam floats 1, and the bottoms of the two outer nets are connected with the bottom of the inner net through a lower line 4; the inner net comprises a plurality of detachably connected first single-layer mesh sheets 5, and the outer net comprises a plurality of detachably connected second single-layer mesh sheets 6.

[0029] The floating net 10 is used to capture fish in the upper layer, and the sinking net 11 is used to capture fish in the bottom layer. The use of the floating net 10 or the sinking net 11 to conduct fishery resource surveys in different waters can be determined according to actual use needs, or the floating net 10 and the sinking net 11 can be used at the same time. The mesh of the inner net is smaller than that of the outer net, and the inner net is located between the two outer nets. Therefore, small fish will still be captured by the inner net after passing through the mesh of the outer net, thereby achieving the capture of small fish. The setting of the two layers of outer nets, on the one hand, achieves the capture of large fish, and on the other hand, the two layers of outer nets improve the firmness and winding and wrapping ability of the multi-layer nets, making it difficult for large fish to break away from the outer net, and then making it difficult for the multi-layer nets to be damaged, making it difficult for fish to escape, thereby more accurately reflecting the true species composition, individual size, density and biomass characteristics of the reservoir fish resources.

[0030] In the present technical solution, the inner net is composed of a plurality of detachably connected first single-layer nets 5, and the outer net is composed of a plurality of detachably connected second single-layer nets 6. When any of the first single-layer nets 5 or the second single-layer nets 6 is damaged, the first single-layer net 5 or the second single-layer net 6 can be replaced, thereby increasing the service life of the outer net and the inner net.

[0031] In the present technical solution, the top ends of several first single-layer meshes 5 and several second single-layer meshes 6 are passed through the upper line 3, and the bottom ends of several first single-layer meshes 5 and several second single-layer meshes 6 are passed through the lower line 4. The foam float 1 provides upward buoyancy for the inner net and the two outer nets, and the lead sinker 2 provides downward gravity for the inner net and the two outer nets, so that the inner net and the two outer nets can be normally unfolded in the water.

[0032] In this technical solution, the first single-layer mesh 5 and the second single-layer mesh 6 of the floating net 10 are both 5m high and 2.5m long, and the total length of the floating net 10 is 30m. The first single-layer mesh 5 and the second single-layer mesh 6 of the sinking net 10 are both 1.5m high and 2.5m long, and the total length of the sinking net 10 is 30m.

[0033] In a further optimized solution, the number of first single-layer mesh sheets 5 is 12, the mesh sizes of the 12 first single-layer mesh sheets 5 are all different, the mesh size of the first single-layer mesh sheet 5 is a first value, and the first value range is 5mm to 55mm. The first value refers to the distance between the inner edges of two diagonal knots when the mesh is fully straightened without stretching. The inner net is composed of 12 first single-layer mesh pieces 5 with a length of 2.5 and different mesh specifications. The range of the first value of the mesh size is 2a. The arrangement order of the mesh pieces is 2a=43mm, 19.5mm, 6.25mm, 10mm, 55mm, 8mm, 12.5mm, 24mm, 15.5mm, 5mm, 35mm, 29mm. The mesh size is formulated according to the international standard of European fishing gear, which can make the types and sizes of catches richer. The mesh wire diameters are r=0.20mm, 0.15mm, 0.10mm, 0.12mm, 0.25mm, 0.10mm, 0.12mm, 0.17mm, 0.15mm, 0.10mm, 0.20mm, 0.17mm.

[0034] In the present technical solution, the first single-layer mesh 5 can be a nylon brown wire mesh.

[0035] Further optimization scheme, the number of second single-layer mesh sheets 6 is 12, two second single-layer mesh sheets 6 are arranged corresponding to the first single-layer mesh sheet 5, the mesh size of the second single-layer mesh sheet 6 is a second value, and the second value is twice the first value. Two second single-layer mesh sheets 6 are respectively arranged on both sides of any first single-layer mesh sheet 5, and the mesh size of the second single-layer mesh sheet 6 is twice the mesh size of the first single-layer mesh sheet 5 at the relative position, that is, the value range of the second value is 4a.

[0036] According to a further optimized solution, any first single-layer mesh 5 is detachably connected to an adjacent first single-layer mesh 5 through a zipper 7, and any second single-layer mesh 6 is detachably connected to an adjacent second single-layer mesh 6 through a zipper 7. Adjacent first single-layer meshes 5 or adjacent second single-layer meshes 6 are sutured through a zipper 7 with a diameter of 1 cm, which is convenient for disassembly. When any first single-layer mesh 5 or second single-layer mesh 6 is damaged, the damaged first single-layer mesh 5 or second single-layer mesh 6 can be taken out and replaced through the zipper 7, and when picking up fish, it can be determined whether the zipper 7 on the two layers of outer nets needs to be opened in combination with actual conditions, so as to facilitate picking up fish caught between the outer net and the inner net.

[0037] Further optimization scheme, the gravity of the lead sinker 2 on the floating net 10 is less than the buoyancy of the foam float 1 on the floating net 10, and the gravity of the lead sinker 2 on the sinking net 11 is greater than the buoyancy of the foam float 1 on the floating net 10. The floating net 10 is required to catch fish in the middle and upper layers, and the buoyancy generated by its foam float 1 should be 1.5-2.5 times that of the lead sinker 2. The sinking net 11 is required to catch bottom fish, and the sinking force generated by the lead sinker 2 should be 1.5-2 times that of the foam float 1.

[0038] Further optimization scheme, a through hole 8 is opened at the center of the foam float 1, the upper line 3 passes through the through hole 8, and the upper line 3 is slidably connected with the foam float 1, and a through groove 9 is opened in the foam float 1, and the through groove 9 is connected with the through hole 8. The center of the foam float 1 is hole-shaped, so as to facilitate the insertion of the upper line 3, so that the foam float 1 can be moved and fixed along the upper line 3. In the prior art, when sorting the nets, multiple foam floats 1 are easily mixed together. By opening the through groove 9 in the foam float 1, the foam float 1 can be moved and fixed on the upper line 3, so as to facilitate the sorting of the nets and improve the efficiency of fish investigation.

[0039] Further optimization scheme, the upper wire 3 and the lower wire 4 are both made of polyethylene. The upper wire 3 is the wire rope that bears the main force of the net at the upper edge of the inner net and the outer net, and the lower wire 4 is the wire rope that bears the main force at the lower edge of the inner net and the outer net. Among them, the lower wire 4 of the sinking net 11 is also called the force wire, and the use of the upper wire 3 and the lower wire 4 belongs to the existing technology, which will not be described in detail here.

[0040] In the present technical solution, the size of the upper wire 3 and the lower wire 4 is preferably 6 mm in diameter and 30 m in length.

[0041] To further optimize the solution, the distance between several foam floats 1 is 20 cm, and the distance between several lead sinkers 2 is 20 cm. A foam float 1 is tied to the upper line 3 every 20 cm, and a lead sinker 2 is tied to the lower line 4 every 20 cm, so that the inner net and the outer net can stretch vertically in the water. The lead sinker 2 is connected to the lower edge of the inner net and the outer net through a short connecting rope, and the foam float 1 is connected to the upper edge of the inner net and the outer net through a short connecting rope and a long connecting rope. The connection method of the foam float 1 to the upper line 3 and the connection method of the lead sinker 2 to the lower line 4 are existing technologies and will not be elaborated on here.

[0042] Actual operation process:

[0043] During the actual operation, at 5:00-7:00 in the evening, at the selected sampling points in the reservoir, three layers of multi-mesh floating nets 10 and sinking nets 11 are used in combination at each sampling point. The number is determined according to the size of the water surface, and the real-time water environment is measured during use. One end of the multi-mesh composite gill net is placed in the water from the sampling boat, and the foam float 1 floats on the water surface. The multi-layer nets are placed in the water at a uniform speed while the sampling boat is moving. While placing the net, the foam float 1 can be rotated and stuck on the upper line 3, and a small red flag or a buoy is tied to the upper line 3 and stands on the water surface to mark and fix the nets.

[0044] The multi-layer net of the floating net is vertically extended in the water under the action of the foam float 1 and the lead sinker 2. When the floating net 10 is set, when the buoyancy of the foam float 1 is greater than the gravity of the lead sinker 2, the multi-layer net is set on the surface layer in the water; when the sinking net 11 is set, when the buoyancy of the foam float 1 is less than the gravity of the lead sinker 2, the multi-layer net is set on the bottom layer in the water, and the pulling action of the foam float 1 and the lead sinker 2 plays the effect of fixing the position of the multi-layer net in the water.

[0045] The next morning, the net is collected at 5:00-7:00. First, the long connecting rope and the lead sinker 2 at one end are lifted, and then the multi-layer net is evenly collected while the sampling boat is moving. Finally, the long connecting rope and the lead sinker 2 at one end are lifted. When the fish caught by the net are removed, it can be judged whether it is necessary to open the zipper 7 of the outer net according to the actual situation. Opening the zipper 7 can improve the efficiency of picking the fish. The fish caught at different sampling points are collected separately and brought back to the room for species identification. The various fish caught in the floating net 10 and the sinking net 11 are identified, counted, weighed and measured in length, and the density and biomass of the various fish caught per unit time are calculated. Finally, the foam float 1 on the upper line 3 is slid to one end and tied.

[0046] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0047] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A three-layer multi-mesh composite gillnet device for investigating fish resources in a reservoir, comprising a floating net (10) for capturing upper layer fish and a sinking net (11) for capturing bottom layer fish, wherein the floating net (10) is located above the sinking net (11), and is characterized in that: The floating net (10) and the sinking net (11) both include a multi-layer net, the top of the multi-layer net is connected to a plurality of foam floats (1) via an upper line (3), and the bottom of the multi-layer net is connected to a plurality of lead sinkers (2) via a lower line (4); The multi-layer net includes two outer nets arranged opposite to each other, an inner net is arranged between the two outer nets, the top ends of the two outer nets are connected to the top end of the inner net by an upper line (3) and are wound around the foam float (1), and the bottom ends of the two outer nets are connected to the bottom end of the inner net by a lower line (4); The inner net garment comprises a plurality of detachably connected first single-layer net sheets (5), and the outer net garment comprises a plurality of detachably connected second single-layer net sheets (6); The number of the first single-layer mesh sheets (5) is 12, the mesh sizes of the 12 first single-layer mesh sheets (5) are all different, the mesh size of the first single-layer mesh sheets (5) is a first value, and the first value range is 5 mm to 55 mm; The number of the second single-layer mesh sheets (6) is 12, two of the second single-layer mesh sheets (6) are arranged corresponding to the first single-layer mesh sheets (5), the mesh size of the second single-layer mesh sheets (6) is a second value, and the second value is twice the first value; Any of the first single-layer mesh sheets (5) is detachably connected to an adjacent first single-layer mesh sheet (5) via a zipper (7), and any of the second single-layer mesh sheets (6) is detachably connected to an adjacent second single-layer mesh sheet (6) via the zipper (7); A through hole (8) is provided at the center of the foam float (1), the upper line (3) passes through the through hole (8), and the upper line (3) is slidably connected to the foam float (1), and a through groove (9) is provided in the foam float (1), and the through groove (9) is connected to the through hole (8).

2. The three-layer multi-mesh composite gillnet device for investigating reservoir fish resources according to claim 1 is characterized in that: The weight of the lead sinker (2) on the floating net (10) is smaller than the buoyancy of the foam float (1) on the floating net (10), and the weight of the lead sinker (2) on the sinking net (11) is larger than the buoyancy of the foam float (1) on the floating net (10).

3. The three-layer multi-mesh composite gillnet device for investigating reservoir fish resources according to claim 1 is characterized in that: The upper main line (3) and the lower main line (4) are both made of polyethylene.

4. The three-layer multi-mesh composite gillnet device for investigating reservoir fish resources according to claim 1 is characterized in that: The distance between a plurality of the foam floats (1) is 20 cm, and the distance between a plurality of the lead sinkers (2) is 20 cm.

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