Device and method for catching invasive fishes through trawl in variable water layers

Abstract

The invention discloses a device and a method for catching invasive fishes through a variable-water-layer trawl, the device comprises an adjuster and a trawl assembly, the adjuster is connected with the trawl assembly through a tow rope, and one end of the adjuster is connected with a cable. The angle between the adjusting plate and the bottom plate is controlled through the air cylinder, so that the water layer where the adjuster is located is controlled in the trawl fishing process, and then fishing of fishes in different water layers is guaranteed. The fishing net is connected through the connecting plate and the fixing frame, the opening of the fishing net is in an open state, and underwater stones or soil blocks are prevented from entering the fishing net through the baffle. The trawl net is convenient to use, easy to maintain and suitable for being used in water areas such as natural lakes or artificial reservoirs with large water depths and a large number of alien invading blue sunfishes, the trawl net depth can be accurately and rapidly changed, and the invading fish catching efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of fishing, and in particular relates to a device and method for catching invasive fish with a variable water layer trawl. Background Art

[0002] Alien invasive fish have posed a serious threat to freshwater aquatic ecosystems and have become an obstacle to maintaining local ecological health and protecting natural resources. For blue sunfish, it was introduced to China in the 1980s due to the need to develop aquaculture at the time. Subsequently, due to aquaculture escape and other reasons, it quickly invaded many water systems south of the Yangtze River in my country. With its strong growth and development performance and strong environmental adaptability, it has now established a stable population in various water bodies over a wide range and has a rapid expansion trend. Therefore, it is urgent to carry out concentrated fishing of invasive blue sunfish in waters with high population density in a timely manner to reduce its individual number (especially breeding individuals) and control its further expansion of the population.

[0003] However, fishing for invasive blue sunfish in natural lakes or artificial reservoirs will affect the fishing efficiency due to the depth of the water body. Among the existing large water body fishing, trawling is a more common method. Fishing can be carried out after locating the fish school through the fishing boat sonar, but because the water layer where the fish school is located is not fixed, a trawling device that can quickly change the water layer is required.

[0004] The patent document with publication number CN111990346A discloses a water layer adjustment mechanism for a trawl net of Antarctic krill and a method thereof. The adjustment mechanism includes a net, a lifting adjustment mechanism, a drag line connection block and a controller. The lifting adjustment mechanism is installed at the inner side of the middle part of the front end of the net along the height direction of the net. The drag line connection block is installed on the lifting adjustment mechanism and can be driven by the lifting adjustment mechanism to move up and down. The drag line connection block is connected to the drag line, and the controller controls the driving of the lifting adjustment mechanism. The invention can dynamically adjust the posture of the net during the fishing operation to achieve the purpose of adjusting the depth of the trawl water layer. However, the mechanism is used for trawl fishing of Antarctic krill, and the use environment is not freshwater waters. The mechanism lacks impact protection for the drag line connection, and the corresponding connected trawl structure is not disclosed.

[0005] The patent document with the publication number CN104938441A discloses a fishing device. The invention aims to solve the problems in the prior art that the catch is small when fishing with fish hooks and small fish nets, the labor input is large, and it is not suitable for large-scale fishing. When fishing with large fishing nets, the fishing efficiency is low, and the survival rate of fishing is low when fishing with electronic fishing methods. The fish cannot be effectively utilized, resulting in waste of resources, and the fish cannot be classified by type. It includes a collection mechanism, a display mechanism, two fishing boats, two supporting mechanisms, and two lifting mechanisms; the collection mechanism includes a collection frame and a fishing net; the lifting mechanism includes a motor, a rotating shaft, a bait support basket, multiple rotating shaft supports, and multiple ropes. However, the invention classifies fish by different baits, and requires the coordinated use of two trawlers, so the fishing cost is relatively high; at the same time, the invention does not involve a technical solution for stable fishing in variable water layers.

[0006] The patent document with publication number CN113180016A discloses a trawling fishing device and a method of using the same, including a floating block, a main net bag, a fish net bag, a grille plate, a semicircular tube, a guide mechanism, an escape mechanism and a separation mechanism, wherein a separation tube is provided on the floating block, the main net bag is fixedly connected to one end of the separation tube, the fish net bag is fixedly connected to the other end of the separation tube, the grille plate is vertically fixed in the separation tube, the grille plate is connected to the upper side wall and the left and right side walls of the separation tube, a plurality of first filter holes are provided on the grille plate, the two ends of the semicircular tube are respectively fixedly connected to the left and right side walls of the separation tube, the upper side edge of the semicircular tube is fixedly connected to the lower side edge of the grille plate through a straight plate, the lower side edge of the semicircular tube is fixedly connected to the lower side wall of the separation tube, the guide mechanism can guide the turtles entering the separation tube into the semicircular tube, the escape mechanism can make the turtles entering the semicircular tube escape from the separation tube, and the separation mechanism can separate the fish and shrimps in the separation tube. The device cannot adjust the water depth of the fishnet in the water through the float or adjust the lifting direction during towing, and the depth of the water layer is not easy to change.

[0007] The patent document with publication number CN113291423A discloses a front-mounted extended trawl device for fishing vessels based on surface fishing, comprising a telescopic positioning structure, a net mouth supporting structure, a fishing net body, a fishing lifting and landing structure, a lifting segment structure and a lifting and sealing structure; the device can drive the telescopic positioning structure to establish a fishing net body in front of the hull structure through the telescopic driving structure, and maintain the entrance end of the fishing net body at a predetermined distance in front of the hull structure with the help of the net mouth supporting structure, so as to catch the fish located in the top water area and enter the fishing net body from the entrance end; the lifting and landing movement of the fishing lifting and landing structure can synchronously drive the lifting segment structure and the lifting and sealing structure, and the fish gathered at the tail end of the fishing net body can be individually lifted up through the lifting segment structure, and an outlet channel can be formed at the tail end of the fishing net body through the lifting and sealing structure and further drive the outlet channel to rise, so that the fish can fall into a specific container of the hull structure with the help of their own gravity. However, the fishing net is connected to the fishing boat through a telescopic positioning structure, and the depth of the fishing net is limited. At the same time, the fishing net is arranged at the bow, which will have a certain impact on the stability of the hull when driving at high speed.

[0008] The patent document with publication number CN202896839U discloses a variable water layer trawl net, including a net body, the net body including an upper panel, a lower panel and a trawl plate, the upper panel and the lower panel are arranged on both sides of the trawl plate, a trawl iron is arranged at the lower end of the lower panel, and a receiving portion for placing a counterweight plate is arranged in the trawl iron. The utility model adjusts the weight of the net by adding or reducing the counterweight plate on the net, so that the net can be used in different water layers. However, the net sinks to different water layers by adding or reducing the counterweight block, and lacks a mechanism that can actively adjust the lifting of the net in the water when trawl fishing. Summary of the invention

[0009] In order to solve the above technical problems, the present invention provides a device and method for catching invasive fish using a variable water layer trawl.

[0010] The present invention is achieved through the following technical solutions.

[0011] The present invention provides a variable water layer trawl device for catching invasive fish, comprising a regulator and a trawl assembly. The regulator is connected to the trawl assembly through a tow rope, and one end of the regulator is connected to a cable.

[0012] Preferably, the regulator includes a base plate and an adjustment plate, a cylinder, a support rod and a connector are arranged on the base plate, the base plate is connected to the adjustment plate through the cylinder and the support rod, the connector is connected to the cable, a buckle A is arranged on one side of the regulator, and the regulator is connected to the tow rope through the buckle A.

[0013] Preferably, the trawl net assembly comprises a connecting plate, a baffle, a fixing frame and a fishing net, one side of the connecting plate is connected to the baffle, and the other side of the connecting plate is connected to the fixing frame, a buckle B is provided at one end of the baffle, and the connecting plate is connected to the tow rope through the buckle B, a screw hole A is provided on the fixing frame, and the fixing frame is connected to the fishing net through bolts and the screw hole A, and the fixing frame and the connecting plate form a rectangular frame, which is the entrance of the fishing net.

[0014] Preferably, the connector includes a fixed frame and a rotating drum, the fixed frame is connected to the rotating drum through a rotating shaft A, the fixed frame is connected to the bottom plate, a baffle A is arranged on the fixed frame, one end of the baffle A is arc-shaped, the material of the baffle A includes rubber or silicone, and the top surface of the adjustment plate is arc-shaped.

[0015] Preferably, a connecting head is provided on the rotating drum, a groove is provided on the connecting head, a buckle C is provided in the groove, and the buckle C is connected to the cable.

[0016] Preferably, a monitor is provided on the baffle, the baffle is triangular in shape, and a pull rope is provided on the fishing net.

[0017] Preferably, a placement groove is provided on the bottom plate, a screw hole B and a counterweight block are provided in the placement groove, and the counterweight block is connected and fixed to the placement groove via the screw hole B and bolts.

[0018] Preferably, a controller and a battery are arranged on the bottom plate, the controller is electrically connected to the battery and the cylinder, the battery is electrically connected to the cylinder, a baffle B is arranged at one end of the bottom plate, one end of the baffle B is arc-shaped, and the material of the baffle B includes rubber or silicone.

[0019] Preferably, a connecting piece and a rotating shaft are provided on the adjustment plate, the connecting piece and the rotating shaft are rotatably connected, and the adjustment plate is connected to the cylinder telescopic rod and the support rod through the rotating shaft.

[0020] A method for using a variable water layer trawl device for catching invasive fish comprises the following steps:

[0021] S1: Connect the cable and the pull rope to the fishing boat, connect the controller to the fishing boat control system, put the trawling device into the water, start the fishing boat, control the extension of the telescopic rod of the cylinder to control the tail of the adjustment plate to rise, and the adjustment plate and the bottom plate to be in an inclined state, so that the trawling device moves downward, and at the same time, lengthen the cable until it reaches the depth monitor feedback data control system, and control the cylinder to make the bottom plate adjustment plate parallel to the bottom plate, then start trawling.

[0022] S2: If the trawling device is to be sunk during trawling, the telescopic rod of the cylinder can be controlled to extend, and the tail of the adjusting plate can be controlled to rise, so that the trawling device rises during the forward movement. If the trawling device is to be raised, the telescopic rod of the cylinder can be controlled to contract, and the tail of the adjusting plate can be controlled to descend, so that the trawling device sinks during the forward movement. After fishing, the mouth of the fishing net can be closed by pulling the draw rope, and the trawling device can be pulled up by retracting the cable rope to complete the trawling operation.

[0023] The beneficial effects of the present invention are:

[0024] The present invention controls the angle between the regulating plate and the bottom plate through a cylinder, thereby controlling the water layer where the regulator is located during trawling, thereby ensuring the capture of fish in different water layers. The fishing net is connected to the fixing frame through a connecting plate, and the opening of the fishing net is opened, and the baffle is used to prevent stones or soil blocks on the bottom of the water from entering the fishing net, thereby affecting the fishing operation. The present invention is easy to use and simple to maintain, and is suitable for use in waters with large water depths such as water conservancy hubs or large dams. It can accurately and quickly change the depth of the trawling net, is suitable for the capture of blue sunfish, and can improve the capture efficiency of blue sunfish. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the present invention;

[0026] Figure 2 It is a structural schematic diagram of the connecting plate of the present invention;

[0027] Figure 3 It is a structural schematic diagram of the bottom plate of the present invention;

[0028] Figure 4 is a rear view structural schematic diagram of the regulator of the present invention;

[0029] Figure 5 is a schematic diagram of the side structure of the regulator of the present invention;

[0030] In the figure: 1-regulator, 11-buckle A, 2-trawl assembly, 21-connecting plate, 22-baffle, 23-fixed frame, 24-fishing net, 25-screw hole A, 26-monitor, 27-pull rope, 3-tow rope, 4-cable, 5-bottom plate, 51-cylinder, 52-support rod, 53-placement groove, 54-screw hole B, 55-counterweight, 56-controller, 57-battery, 58-baffle B, 6-adjustment plate, 61-connector, 62-rotating shaft, 7-connector, 71-fixed frame, 72-rotating shaft A, 73-baffle A, 9-rotating drum, 91-connector, 92-groove, 93-buckle C, 10-buckle B. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0032] Embodiment 1:

[0033] like Figures 1 to 5 As shown, a variable water layer trawl device for catching invasive fish includes a regulator 1 and a trawl assembly 2. The regulator 1 is connected to the trawl assembly 2 through a tow rope 3, and one end of the regulator 1 is connected to a cable 4.

[0034] The regulator 1 includes a base plate 5 and an adjustment plate 6, and the end of the regulator 1 connected to the cable 4 is the front end. A cylinder 51, a support rod 52 and a connector 7 are arranged on the base plate 5. The base plate 5 is connected to the adjustment plate 6 through the cylinder 51 and the support rod 52. Two support rods 52 are symmetrically arranged on the top surface of the front end of the base plate 5. The cylinder 51 is arranged on the top surface of the rear end of the base plate 5. The connector 7 is connected to the cable 4. The connector 7 is arranged on the top surface of the front end of the base plate 5. A buckle A11 is arranged on one side of the regulator 1. Several buckles A11 can be arranged as needed. Each buckle A11 is connected to a tow rope 3. The regulator 1 is connected to the tow rope 3 through the buckle A11, and the tow rope 3 is connected to the rear end of the regulator 1.

[0035] The trawl assembly 2 includes a connecting plate 21, a baffle 22, a fixing frame 23 and a fishing net 24, one side of the connecting plate 21 is connected to the baffle 22, one end of the baffle 22 is the front end of the trawl assembly 2, the other side of the connecting plate 21 is connected to the fixing frame 23, a buckle B10 is provided at one end of the baffle 22, the connecting plate 21 is connected to the tow rope 3 through the buckle B10, a plurality of screw holes A25 are provided on the fixing frame 23, the fixing frame 23 is connected to the fishing net 24 through bolts and the screw holes A25, the fixing frame 23 can be C-shaped, the length of both sides of the fixing frame 23 can be selected as needed, the fixing frame 23 and the connecting plate 21 form a rectangular frame, the frame is the entrance of the fishing net 24, and the fishing net 24 can use a commercially available fishing net.

[0036] The connector 7 includes a fixed frame 71 and a rotating drum 9. The fixed frame 71 is connected to the rotating drum 9 through a rotating shaft A72. The rotating drum 9 can be rotated on the fixed frame 71 and rotated at a certain angle after being connected to the cable 4 through the rotating drum 9, so as to keep the regulator 1 horizontal during trawling fishing and avoid interference with the lifting and lowering of the regulator 1. The fixed frame 71 is connected to the bottom plate 5. A baffle A73 is arranged on the fixed frame 71. One end of the baffle A73 is arc-shaped. The baffle A73 is made of rubber or silicone, which is relatively soft and can play a buffering role when the connecting head 91 collides. The baffle A73 is arranged above the connecting head 91 to limit the upward rotation of the rotating drum 9 to prevent the rotating drum 9 from contacting the adjusting plate 6 and affecting the direction adjustment of the regulator 1. The top surface of the adjusting plate 6 is arc-shaped, which can reduce the water flow resistance and is also convenient for controlling the direction of the regulator 1.

[0037] A connector 91 is provided on the rotating drum 9, a groove 92 is provided on the connector 91, a buckle C93 is provided in the groove 92, and the buckle C93 is connected to the cable 4. This arrangement can protect the buckle C93 when the connector 91 touches a reef or the bottom of the water, thereby preventing the buckle C93 from being separated from the cable 4 due to damage due to impact.

[0038] A monitor 26 is arranged on the baffle 22. The monitor 26 has a signal receiving and sending function and a built-in rechargeable battery. The monitor 26 can monitor the water depth and water flow parameters and provide feedback to the fishing boat control system. The baffle 22 is triangular in shape, which is convenient for reducing water resistance and can guide large objects that are touched to both ends. The height of the baffle 22 is greater than the height of the connecting plate 21, which can prevent gravel or large pieces of soil from entering the fishing net 24 when the trawl assembly 2 touches reefs or the bottom of the water. A pull rope 27 is arranged on the fishing net 24, and the pull rope 27 is connected to the fishing boat. At the end of trawling, the pull rope 27 can be pulled to close the mouth of the fishing net 24 to prevent fish from swimming out of the fishing net 24.

[0039] The bottom plate 5 is provided with placement grooves 53, which are symmetrically arranged on both sides of the bottom plate 5. The placement grooves 53 are provided with screw holes B54 and counterweights 55, and the counterweights 55 are connected and fixed to the placement grooves 53 through the screw holes B54 and bolts. The counterweights 55 can be used or not according to actual needs. Placing the counterweights 55 can enable the trawling device to reach deeper waters faster.

[0040] A controller 56 and a battery 57 are arranged on the bottom plate 5, and the controller 56 is electrically connected to the battery 57 and the cylinder 51. The controller 56 has a signal receiving and sending function, and can control the cylinder 51 by wirelessly connecting to the fishing vessel control system. The battery 57 is electrically connected to the cylinder 51. A baffle B58 is arranged at one end of the bottom plate 5, and one end of the baffle B58 is arc-shaped. The baffle B58 is made of rubber or silicone, which is relatively soft and can play a buffering role when the connecting head 91 collides. The baffle B58 is arranged below the connecting head 91 to limit the downward rotation of the rotating drum 9 to prevent the rotating drum 9 from colliding with the bottom plate 5 and causing damage.

[0041] The adjusting plate 6 is provided with a connecting piece 61 and a rotating shaft 62 , and the connecting piece 61 and the rotating shaft 62 are rotatably connected. The adjusting plate 6 is connected to the telescopic rod of the cylinder 51 and the supporting rod 52 via the rotating shaft 62 .

[0042] A method for using a variable water layer trawl device for catching invasive fish comprises the following steps:

[0043] S1: Connect the cable 4 and the pull rope 27 to the fishing boat, connect the controller 56 to the fishing boat control system, put the trawling device into the water, start the fishing boat, and control the extension of the telescopic rod of the cylinder 51 to control the tail of the adjusting plate 6 to rise. The adjusting plate 6 and the bottom plate 5 are in an inclined state. At this time, the front end of the adjusting plate 6 is close to the front end of the bottom plate 5, so that the trawling device moves downward. At the same time, the cable 4 is lengthened until it reaches the depth monitor 26 feedback data control system. By controlling the cylinder 51, the adjusting plate 6 and the bottom plate 5 are parallel. At this time, trawling fishing begins.

[0044] S2: If the trawling device is to be sunk during trawling, the telescopic rod of the cylinder 51 can be controlled to extend, and the tail of the adjusting plate 6 can be controlled to rise, so that the trawling device rises during the forward movement. If the trawling device is to be raised, the telescopic rod of the cylinder 51 can be controlled to contract, and the tail of the adjusting plate 6 can be controlled to be lowered. At this time, the front end of the adjusting plate 6 is away from the front end of the bottom plate 5, and the adjusting plate 6 and the bottom plate 5 are in an inclined state, so that the trawling device sinks during the forward movement. During the rising or falling process of the trawling device, the cable 4 can be lengthened or shortened as needed. After fishing, the mouth of the fishing net 24 is tightened by pulling the pull rope 27, and the trawling device is pulled up by retracting the cable 4 to complete the trawling operation.

[0045] Comparative Example 1:

[0046] Trawling is performed using only the fishing net 24 as a fishing device.

[0047] The devices and methods of Example 1 and Comparative Example 1 were used to carry out trawling fishing in the Hongjiadu Reservoir area using fishing boats equipped with sonar. The fishing nets were all set to catch fish weighing more than 1.5 kg. The fishing results are shown in the following table.

[0048] Fish catch in 3 hours (kg) Fish catch in 6 hours (kg) Example 1 674.9 1074.5 Comparative Example 1 211.4 547.3

[0049] In the above table, the 3-hour and 6-hour catches of Example 1 were increased by 68.7% and 49.1% respectively compared with those of Comparative Example 1. It can be seen that the use of the device of the present application can effectively improve the fishing efficiency compared with the use of a fishing net for trawling.

Claims

1. A variable water layer trawl device for catching invasive fish, characterized in that: The invention comprises a regulator (1) and a trawl assembly (2); the regulator (1) is connected to the trawl assembly (2) via a towing rope (3); one end of the regulator (1) is connected to a cable (4).

2. The variable water layer trawl device for catching invasive fish as claimed in claim 1, characterized in that: The regulator (1) comprises a base plate (5) and an adjustment plate (6); a cylinder (51), a support rod (52) and a connector (7) are arranged on the base plate (5); the base plate (5) is connected to the adjustment plate (6) via the cylinder (51) and the support rod (52); the connector (7) is connected to the cable (4); a buckle A (11) is arranged on one side of the regulator (1); and the regulator (1) is connected to the towing rope (3) via the buckle A (11).

3. The variable water layer trawl device for catching invasive fish as claimed in claim 1, characterized in that: The trawl assembly (2) comprises a connecting plate (21), a baffle (22), a fixing frame (23) and a fishing net (24); one side of the connecting plate (21) is connected to the baffle (22); the other side of the connecting plate (21) is connected to the fixing frame (23); a buckle B (10) is provided at one end of the baffle (22); the connecting plate (21) is connected to the towing rope (3) via the buckle B (10); a screw hole A (25) is provided on the fixing frame (23); the fixing frame (23) is connected to the fishing net (24) via a bolt and the screw hole A (25); the fixing frame (23) and the connecting plate (21) form a rectangular frame, and the frame is an entrance to the fishing net (24).

4. The variable water layer trawl device for catching invasive fish as claimed in claim 2, characterized in that: The connector (7) comprises a fixing frame (71) and a rotating drum (9), wherein the fixing frame (71) is connected to the rotating drum (9) via a rotating shaft A (72), the fixing frame (71) is connected to the bottom plate (5), a baffle A (73) is arranged on the fixing frame (71), one end of the baffle A (73) is arc-shaped, the material of the baffle A (73) comprises rubber or silicone, and the top surface of the adjusting plate (6) is arc-shaped.

5. The variable water layer trawl device for catching invasive fish as claimed in claim 4, characterized in that: The rotating drum (9) is provided with a connecting head (91), the connecting head (91) is provided with a groove (92), a buckle C (93) is provided in the groove (92), and the buckle C (93) is connected to the cable (4).

6. The variable water layer trawl device for catching invasive fish as claimed in claim 3, characterized in that: A monitor (26) is arranged on the baffle (22), the baffle (22) is triangular in shape, and a pull rope (27) is arranged on the fishing net (24).

7. The variable water layer trawl device for catching invasive fish as claimed in claim 2, characterized in that: A placement groove (53) is provided on the bottom plate (5), a screw hole B (54) and a counterweight block (55) are provided in the placement groove (53), and the counterweight block (55) is connected and fixed to the placement groove (53) via the screw hole B (54) and bolts.

8. The variable water layer trawl device for catching invasive fish as claimed in claim 2, characterized in that: A controller (56) and a battery (57) are arranged on the bottom plate (5), the controller (56) and the battery (57) are electrically connected to the cylinder (51), and the battery (57) is electrically connected to the cylinder (51). A baffle plate B (58) is arranged at one end of the bottom plate (5), one end of the baffle plate B (58) is arc-shaped, and the material of the baffle plate B (58) includes rubber or silicone.

9. The variable water layer trawl device for catching invasive fish as claimed in claim 2, characterized in that: The adjusting plate (6) is provided with a connecting piece (61) and a rotating shaft (62), the connecting piece (61) and the rotating shaft (62) are rotatably connected, and the adjusting plate (6) is connected to the telescopic rod of the cylinder (51) and the supporting rod (52) via the rotating shaft (62).

10. A method for using the variable water layer trawl device for catching invasive fish as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: S1: Connect the cable (4) and the pull rope (27) to the fishing boat, connect the controller (56) to the control system of the fishing boat, put the trawling device into the water, start the fishing boat, control the telescopic rod of the cylinder (51) to extend, control the tail of the adjustment plate (6) to rise, and make the adjustment plate (6) and the bottom plate (5) tilted, so that the trawling device moves downward, and at the same time, let the cable (4) lengthen, and wait until the depth monitor (26) feedback data control system is reached, and control the cylinder (51) to make the bottom plate (5) and the adjustment plate (6) parallel to the bottom plate (5), and then start trawling; S2: During the trawling process, if the trawling device is to be sunk, the telescopic rod of the cylinder (51) can be controlled to extend, and the tail of the adjusting plate (6) can be controlled to rise, so that the trawling device rises during the forward movement. If the trawling device is to be raised, the telescopic rod of the cylinder (51) can be controlled to contract, and the tail of the adjusting plate (6) can be controlled to descend, so that the trawling device sinks during the forward movement. After the fishing is finished, the net mouth of the fishing net (24) is closed by pulling the pull rope (27), and the trawling device is pulled up by the cable rope (4), thereby completing the trawling operation.

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