Crayfish trap attachment

Abstract

To provide an attachment for crayfish capture trap, which uses a conventional and inexpensive crayfish capture trap, for improving capture efficiency of crayfish, has a simplified structure and can be used at a low cost, and can be attached and detached easily.SOLUTION: There is provided an attachment 30 for crayfish capture trap which is attached to a basket trap 10 for crayfish capture, and the attachment for crayfish capture trap comprises: a rectangular sheet 31 having flexibility; a pitfall 32 which is provided on the sheet 31 for making a crayfish fall; and connection members 34 which are provided on a pair of ends of the sheet 31, for connecting the ends of the sheet 31 which is rolled. The sheet 31 can be put into a capture chamber 14 from a take-out hole 15 of a basket trap 10, then the connection member 34 is connected to the ends of the sheet in a state of rolling the sheet 31 in a cylindrical shape so that the edge part of the sheet 31 overlaps to an entrance 22, and the pitfall 32 is directed downward.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an attachment that improves conventional commercially available fish and shellfish traps for use in capturing crayfish. [Background technology]

[0002] American crayfish live in ponds, swamps, agricultural waterways, etc. all over the country. American crayfish have been designated as one of the 100 worst invasive alien species by the Ecological Society of Japan, and are being exterminated in various places because they cause water leakage from rice paddies by digging deep ridges and cause ecosystem degradation by preying on native organisms.

[0003] However, there have been no cases where complete eradication has been successful, and the development of highly efficient eradication techniques is required. As a technique for capturing such crayfish, a cage for capturing crustaceans, etc., which uses a cage with a net as a component, as disclosed in Patent Document 1, has been known.

[0004] The cage for capturing crustaceans and the like in Patent Document 1 comprises a base ring that also serves as a weight, a foldable support member connected to the ring, a cage mesh body stretched around the outer periphery of the cage framework formed by the base ring and the support member, an elliptical entry opening formed in the center of the side of the cage mesh body, a cylindrical entry hole for crustaceans and the like formed inside the cage mesh body, and an elliptical cylindrical non-return part inside the cage mesh body at the entry hole. The tip edge of the non-return part is a free end to which a thread is attached, and is located inside the elliptical inner opening edge of the entry hole, and the diameter gradually decreases toward the inside from the entry opening, forming an elliptical entry path, tapering toward the tip edge, and a non-return part formed continuously with the inner circumferential surface of the entry hole, which protrudes laterally inward from the circumferential surface of the cage mesh body.

[0005] Crayfish are attracted by the smell of bait, climb up the netting, go through the entry hole, and fall into the netting through the non-returning part. However, because their legs get caught in the netting, some crayfish that are caught once climb up the netting, turn upside down, and do not fall back, but instead go back through the entry hole and escape to the outside. This reduces the efficiency of crayfish capture.

[0006] Furthermore, the capture device of Patent Document 2 is known as a capture device that increases the efficiency of crayfish capture. The capture device of Patent Document 2 has a capture section, an isolation section, and an automatic feeding device. The capture section has a capture chamber and an entrance for crayfish. The capture chamber is light-transmitting and can contain crayfish. The entrance allows crayfish to enter the capture chamber from the outside and prevents them from escaping to the outside. The isolation section has a storage chamber and an entrance for crayfish. The storage chamber is light-blocking and can contain crayfish. The storage chamber is located adjacent to the bottom of the capture chamber. The entrance allows crayfish to enter from the capture chamber to the storage chamber and prevents them from retreating back into the capture chamber. The automatic feeding device periodically supplies food to the inside of the capture chamber.

[0007] However, the capture device in Patent Document 2 has a two-tiered structure consisting of a capture chamber and a storage chamber, each with an entrance and requiring an automatic feeding device, resulting in a complex structure and making the entire device expensive. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Utility Model Application Publication No. 61-80663 [Patent Document 2] Japanese Patent Application Publication No. 2017-184644 Summary of the Invention [Problem to be solved by the invention]

[0009] In view of the above, an object of the present invention is to provide an attachment for a crayfish trap that utilizes a conventional, inexpensive fish and shellfish trap to improve the efficiency of capturing crayfish, has a simple structure, is inexpensive to manufacture, and is easy to attach and detach. [Means for solving the problem]

[0010] A crayfish trap attachment for attaching to a cage trap for capturing crayfish, the attachment comprising: a cage body having a net stretched over a frame and a capture chamber formed therein; a funnel-shaped portion that narrows in diameter from the end of the cage body toward the inside and communicates with the capture chamber through an entrance; and an outlet that is openably and closably provided on the cage body and allows captured crayfish to be removed; A flexible rectangular sheet, a hole provided in the sheet through which the crayfish falls, and a connecting member provided at a pair of ends of the sheet and connecting the ends of the sheet rolled into a cylindrical shape, The sheet can be inserted into and removed from the capture chamber through the outlet, and is characterized in that the sheet is rolled into a cylindrical shape and the connecting member is connected so that the edge of the sheet overlaps the entrance, and the drop hole is positioned so that it faces downward, making it detachable from the cage trap.

[0011] According to this configuration, the crayfish trap attachment has a simple configuration including a flexible rectangular sheet, a hole in the sheet through which the crayfish falls, and a connecting member at each end of the sheet that connects the ends of the sheet rolled into a cylindrical shape, thereby reducing manufacturing costs and making it easy to make. Furthermore, the sheet can be inserted into and removed from the trap chamber through the outlet, and the sheet can be rolled into a cylindrical shape and the connecting member connected so that the edge of the sheet overlaps the entrance, and the hole is positioned so that it faces downward, allowing it to be detachably attached to a cage trap, making it easy to attach and detach from existing crayfish traps. Furthermore, because the crayfish trap attachment made of sheet is attached to a cage trap for crayfish capture, even if a captured crayfish tries to escape, it cannot grab the sheet and escape to the outside, thereby improving crayfish capture efficiency.

[0012] In addition, a cage trap for capturing crayfish includes a cage body with a frame covered with a net to form a capture chamber inside, a funnel-shaped portion that narrows from the end of the cage body toward the inside and communicates with the capture chamber through an entrance, and an outlet that is openable and closable and allows captured crayfish to be removed. By attaching an inexpensive crayfish trap attachment to such an inexpensive crayfish trap, overall manufacturing costs can be reduced. As a result, a crayfish trap attachment that utilizes a conventional, inexpensive crayfish trap can be provided that has a simple structure, is inexpensive to manufacture, and is easy to attach and detach.

[0013] Preferably, the connecting members are resin hooks, and a plurality of such hooks are provided at a pair of ends of the sheet.

[0014] With this configuration, the connecting members are made of resin hooks, so they will not rust like metal hooks even if left in water for long periods of time, improving durability in water. Furthermore, since the connecting members are made of resin hooks and multiple hooks are provided at a pair of ends of the sheet, the connection strength is improved, and the overall product strength of the crayfish trap attachment is also improved.

[0015] Preferably, the seat is made of synthetic resin and formed in a rectangular shape, with a length L1 in the front-rear direction of the seat being 30 cm and a length L2 in the width direction of the seat being 26 cm, The trap hole is formed in a rectangular shape, with a length L3 of 9 cm in the front-to-rear direction of the trap hole and a length L4 of 9 cm in the width direction of the trap hole.

[0016] According to this configuration, the sheet is made of synthetic resin and is rectangular, with a length L1 in the front-to-back direction of 30 cm and a length L2 in the width direction of 26 cm, and the trapdoor is rectangular with a length L3 in the front-to-back direction of 9 cm and a length L4 in the width direction of 9 cm, so the sheet has a simple shape and can be manufactured easily and inexpensively.Furthermore, because the trapdoor is rectangular with a length L3 in the front-to-back direction of 9 cm and a length L4 in the width direction of the trapdoor, even large crayfish can be caught, and even if the crayfish tries to escape, the large area of ​​the sheet makes it impossible to grab and prevent it from escaping, thereby improving the efficiency of crayfish capture.

[0017] Preferably, the sheet is made of polyester or polypropylene and has a thickness of 0.3 mm to 0.6 mm.

[0018] According to this configuration, the sheet is made of polyester or polypropylene and has a thickness of 0.3 mm to 0.6 mm, which provides sufficient durability. Also, because the sheet is made of polyester or polypropylene and has a thickness of 0.3 mm to 0.6 mm, it can be manufactured by cutting a thick clear folder that is commonly available on the market with scissors or a cutter, which reduces manufacturing costs.

[0019] Preferably, the sheet is translucent or opaque.

[0020] Generally, crayfish may engage in so-called cannibalism if they remain in a small space for a long time, and may avoid approaching a crayfish larger than themselves in the small space. In this regard, with this configuration, the sheet is translucent or opaque, so the back side of the sheet cannot be seen. Even if a crayfish has previously fallen into the capture chamber through a pitfall, the next crayfish will not be able to see the crayfish in the capture chamber when it passes over the sheet, so it will continue on without avoiding the crayfish and fall into the capture chamber through the pitfall. This improves the efficiency of crayfish capture.

[0021] Preferably, the cage trap has two opposing funnel-shaped portions that decrease in diameter from opposing ends of the cage body toward the inside and communicate with the capture chamber through the inlet, The sheet is attached so that the edges on both sides of the rolled-up cylindrical sheet overlap the inlet openings of the opposing funnel-shaped portions.

[0022] According to this configuration, the edges on both sides of the rolled-up sheet are attached so as to overlap the entrances of the opposing funnel-shaped parts, so that crayfish can be attracted from both sides of the cage trap, improving the efficiency of capturing crayfish. [Effects of the Invention]

[0023] To provide an attachment for a crayfish trap that improves the efficiency of capturing crayfish by utilizing a conventional, inexpensive crayfish trap, has a simple structure, is inexpensive to manufacture, and is easy to attach and detach. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a perspective view of an attachment for a crayfish trap according to an embodiment attached to a cage trap. FIG. [Figure 2] FIG. 1 is a side view of an embodiment of an attachment for a crayfish trap attached to a cage trap. [Figure 3] FIG. 1 is a side view of a cage trap. [Figure 4] FIG. 10 is a perspective view of the basket trap in a folded state. [Figure 5] Fig. 5(A) is a plan view of the attachment for trapping crayfish according to the embodiment, and Fig. 5(B) is a perspective view of the attachment for trapping crayfish according to the embodiment in a cylindrical shape. [Figure 6] Fig. 6(A) is a diagram showing the operation of inserting the attachment for trapping crayfish according to the embodiment into a cage trap. Fig. 6(B) is a diagram showing the operation of attaching the attachment for trapping crayfish according to the embodiment to a cage trap. Fig. 6(C) is a diagram showing the operation of attaching the attachment for trapping crayfish according to the embodiment to a cage trap. [Figure 7] Fig. 7(A) is a diagram showing the operation of a cage trap according to a comparative example, and Fig. 7(B) is a diagram showing the operation of a cage trap equipped with a crayfish trap attachment according to an embodiment. [Figure 8] FIG. 10 is a diagram illustrating the number of individuals captured when using a cage trap according to a comparative example and the number of individuals captured when a crayfish trap attachment according to an embodiment is attached to a cage trap. DETAILED DESCRIPTION OF THE INVENTION

[0025] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings, which conceptually (schematically) show an attachment for a crayfish trap and a cage trap. [Example]

[0026] 1 to 3, a cage trap 10 for capturing crayfish comprises a cage body 11 having a net 13 stretched over an expandable and generally spiral frame 12, forming a capture chamber 14 therein, funnel-shaped portions 21 that taper inward from a pair of ends of the cage body 11 and communicate with the capture chamber 14 via entrances 22, and tension cords 23 that are provided at the opposing entrances 22 and pull against each other to support the funnel-shaped portions 21. The frame 12 is elastic and biases the pair of ends to spread apart in the left-right direction, and is spread apart in its natural state.

[0027] The cage trap 10 for capturing crayfish also includes an outlet 15 that is openably mounted on the cage body 11 and through which captured crayfish 40 (see Figure 7) can be removed, a bait inlet 16 that is openably mounted on the top of the cage body 11, and a bait bag 17 that is connected to the bait inlet 16 and mounted on the top of the cage body 11. The outlet 15 and bait inlet 16 can be opened and closed with zippers.

[0028] As shown in Figure 4, the cage trap 10 for capturing crayfish can be made compact by contracting the frame 12, folding the cage body 11, and winding the retaining cord 19. This saves space and makes it easy to carry.

[0029] As shown in Figures 1 to 3 and 5, the attachment 30 for a crayfish trap is detachably attached to a cage trap for capturing crayfish, and comprises a flexible rectangular sheet 31, a hole 32 provided in the sheet 31 for dropping crayfish 40 into, and connecting members 34 provided at a pair of ends of the sheet 31 to connect the ends 33 of the sheet 31 which are rolled into a cylindrical shape.

[0030] The seat 31 is made of synthetic resin and is rectangular, with a length L1 of 30 cm in the front-to-rear direction and a length L2 of 26 cm in the width direction. The trapdoor 32 is rectangular, with a length L3 of 9 cm in the front-to-rear direction and a length L4 of 9 cm in the width direction.

[0031] As described above, sheet 31 is made of synthetic resin and formed into a rectangular shape, with a length L1 in the front-to-rear direction of 30 cm and a length L2 in the width direction of 26 cm, and pitfall 32 is formed into a rectangular shape with a length L3 in the front-to-rear direction of 9 cm and a length L4 in the width direction of 9 cm, so that sheet 31 has a simple shape and can be manufactured easily and inexpensively. Furthermore, pitfall 32 is formed into a rectangular shape with a length L3 in the front-to-rear direction of 9 cm and a length L4 in the width direction of 9 cm, so that even large crayfish can be caught, and even if the crayfish tries to escape, the large area of ​​sheet 31 makes it impossible for it to be grabbed and to escape to the outside, thereby improving the efficiency of capturing crayfish.

[0032] The sheet 31 is made of polyester (PET) or polypropylene (PP) and has a thickness of 0.3 mm or more and 0.6 mm or less.

[0033] As described above, sheet 31 is made of polyester or polypropylene and has a thickness of 0.3 mm to 0.6 mm, both inclusive, making it sufficiently durable. Also, because sheet 31 is made of polyester or polypropylene and has a thickness of 0.3 mm to 0.6 mm, it can be made by cutting a thick clear folder that is generally available on the market with scissors or a cutter, making it possible to reduce production costs.

[0034] In the examples, the sheet 31 is made of polyester or polypropylene, but is not limited thereto. Other common synthetic resin materials, such as polystyrene (PS) or polycarbonate (PC), may be used as long as they are flexible and water-resistant. In the examples, the thickness of the sheet 31 is set to 0.3 mm or more and 0.6 mm or less. However, a thickness of 0.5 mm is preferable. A thickness of 0.5 mm for the sheet 31 allows for the use of commercially available thick clear folders (clear files), reducing the material cost per trap to 123.5 yen and improving product strength, ease of manufacturing, and ease of attachment and detachment to the basket trap 10. When using a commercially available clear folder (clear file), a crease (not shown) is formed in the center of the sheet 31, allowing for easy folding for transport and storage.

[0035] Furthermore, the sheet 31 is translucent or opaque. Generally, crayfish 40 (see FIG. 7) may engage in so-called cannibalism if they remain in a small space for a long time, and may avoid approaching a crayfish 40 larger than themselves in the small space. In this regard, according to the configuration of the present invention, the sheet 31 is translucent or opaque, so the back side of the sheet 31 is not visible. Even if a crayfish 40 has previously fallen into the capture chamber 14 from the pitfall 32, the next crayfish 40 will not be able to see the crayfish 40 in the capture chamber when it passes over the sheet 31, and will therefore continue forward without avoiding the crayfish 40 and fall into the capture chamber 14 from the pitfall 32. This improves the efficiency of capturing crayfish 40.

[0036] The connecting members 34 are resin hooks, and multiple hooks are provided at a pair of ends 33, 33 of the sheet 31. As such, because the connecting members 34 are resin hooks, they will not rust like metal hooks even if left in water for a long period of time, and durability in water can be improved. Furthermore, because the connecting members 34 are resin hooks and multiple hooks are provided at a pair of ends 33, 33 of the sheet 31, the connection strength can be improved, and the product strength of the crayfish trap attachment 30 as a whole can also be improved.

[0037] The sheet 31 can be taken in and out of the capture chamber 14 through the take-out port 15, and is detachably attached to the cage trap 10 by rolling the sheet 31 into a cylindrical shape and connecting the connecting member 34 so that the edge 35 of the sheet 31 overlaps the entrance 22, and by arranging the hole 32 facing downward.

[0038] The cage trap 10 has two opposing funnel-shaped sections 21 that taper inward from opposing ends of the cage body 11 and communicate with the capture chamber 14 via entrances 22, and the sheet 31 is attached so that the edge sections 35 on both sides of the rolled-up cylindrical sheet 31 overlap the entrances 22 of the opposing funnel-shaped sections 21.

[0039] Next, the procedure for attaching the crayfish trap attachment 30 to the cage trap 10 will be described.

[0040] As shown in FIG. 6(A), the outlet 15 of the cage trap 10 is opened, and the attachment 30 for the crayfish trap is inserted into the trapping chamber 14 through the outlet 15 by bending the sheet 31 or the like.

[0041] As shown in Figure 6 (B), the sheet 31 is rolled into a cylindrical shape so as to cover the pulling string 23, and the connecting member 34 is connected so that the edge 35 of the sheet 31 overlaps the entrance 22 of the funnel-shaped portion 21, and the crayfish capture trap attachment 30 is attached to the cage trap 10 by positioning it so that the drop hole 32 faces downward.

[0042] As shown in Figure 6(C), by closing the outlet 15 of the cage trap 10, the attachment 30 for the crayfish trap is completed to be attached to the cage trap 10. Furthermore, by putting bait into the bait bag 17 through the bait inlet 16, the cage trap 10 is ready.

[0043] When carrying the basket trap 10, the user opens the opening 15, disconnects the connecting member 34, removes the sheet 31, and then removes the sheet 31 from the opening 15. By folding the basket trap 10 (see Figure 4) and the sheet 31, the entire trap can be made thin and compact, making it easy to carry and store. Both installation and removal take less than one minute.

[0044] Next, the operation of the cage trap according to the comparative example and the operation of the cage trap equipped with the attachment for a crayfish trap according to the embodiment will be described.

[0045] As shown in Figure 7(A), the comparative example cage trap 10 comprises a cage body 11 in which a mesh 13 is stretched over a frame 12 and a capture chamber 14 is formed inside, a funnel-shaped portion 21 that narrows in diameter from the end of the cage body 11 toward the inside and communicates with the capture chamber 14 via an entrance 22, and a pull cord 23 that supports the funnel-shaped portion 21 by pulling on the entrance of the funnel-shaped portion (not shown) that faces the entry opening 22 of the funnel-shaped portion 21.

[0046] In the cage trap 10 of the comparative example, the crayfish 40 first enters the capture chamber 14 through the entry port 22 by climbing down the funnel-shaped portion 22, but the legs of the crayfish 40 get caught in the net 13, causing the crayfish 40 to climb up the funnel-shaped portion 21 and escape to the outside through the entry port 22 as shown by arrow (1).

[0047] As shown in Figure 7(A), a crayfish trap attachment 30 is attached to the cage trap 10 of the embodiment. A crayfish 40 travels down the funnel-shaped portion 22, enters the entry port 22 onto the sheet 31 of the crayfish trap attachment 30, and falls into the trapping chamber 14 through the pitfall 32.

[0048] In the cage trap 10 equipped with the crayfish trap attachment 30 of the embodiment, even if a crayfish 40 in the capture chamber 14 climbs up the funnel-shaped portion 40, its legs do not get caught on the sheet 31 of the crayfish trap attachment 30, and it falls back into the capture chamber 14 as shown by arrow (2), preventing it from escaping to the outside. Therefore, the cage trap 10 equipped with the crayfish trap attachment 30 of the embodiment can improve the efficiency of capturing crayfish.

[0049] We will explain the experimental results of the number of individuals captured in an actual pond when using a cage trap (without an attachment) according to the comparative example, and when the crayfish capture trap attachment according to the embodiment is attached to the cage trap.

[0050] As shown in Figure 8, the number of crayfish captured every two weeks from April to October in an actual pond was 203 when using the cage trap of the comparative example (without attachment), and 940 when using the cage trap equipped with the crayfish capture trap attachment of the example. The capture efficiency of the example is more than four times that of the comparative example. The cage trap equipped with the crayfish capture trap attachment of the example captured more individuals in each survey (once every two weeks) than the cage trap of the comparative example (without attachment).

[0051] In a laboratory experiment with a total of 16 crayfish 40, the capture rate was 20.7% when using the cage trap of the comparative example (without attachment), and 62.5% when using the cage trap with the attachment for the crayfish capture trap of the example. The cage trap with the attachment for the crayfish capture trap of the example captured mainly large individuals but also small individuals, and 9 out of 10 individuals confirmed to have entered the cage trap were unable to escape from the cage trap.

[0052] Next, the function and effect of the attachment 30 for a crayfish trap of the embodiment will be described. As described above, the crayfish trap attachment 30 has a simple configuration including a flexible rectangular sheet 31, a hole 32 provided in the sheet 31 for dropping crayfish 40, and connecting members 34 provided at a pair of ends of the sheet 31 and connecting the ends of the sheet 31 rolled into a cylinder, thereby reducing production costs and making it easy to manufacture. Furthermore, the sheet 31 can be taken in and out of the trapping chamber 14 through the outlet 15, and can be detachably attached to a cage trap by rolling the sheet 31 into a cylinder and connecting the connecting members 34 so that the edge 35 of the sheet 31 overlaps the entrance 22, and by positioning the hole 32 facing downward, the attachment can be easily attached and detached to an existing crayfish trap.

[0053] Furthermore, since the attachment 30 for a crayfish trap made up of a sheet 31 is attached to the cage trap 10 for capturing crayfish, even if a captured crayfish 40 tries to escape, it cannot grab the sheet 31 and cannot escape to the outside, thereby improving the efficiency of capturing the crayfish 40.

[0054] Furthermore, the crayfish trap 10 includes a cage body 11 having a net 13 stretched over a frame 31 and a trapping chamber 14 formed therein, a funnel-shaped portion 21 that tapers from the end of the cage body 11 toward the inside and communicates with the trapping chamber 14 via an entrance 22, and an outlet 15 that is openably and closably attached to the cage body 11 and through which captured crayfish 40 can be removed. This inexpensive crayfish trap attachment 30 is attached to this inexpensive crayfish trap 10, thereby reducing overall manufacturing costs. As a result, a crayfish trap attachment 30 can be provided that utilizes a conventional, inexpensive crayfish trap and has a simple structure, is inexpensive to manufacture, and is easy to attach and detach.

[0055] Furthermore, since the edges on both sides of the sheet 31 rolled into a cylindrical shape are attached so as to overlap the entrances 22 of the opposing funnel-shaped parts 21, the crayfish 40 can be attracted from both sides of the cage trap 10, and the efficiency of capturing the crayfish 40 can be improved.

[0056] In the embodiment, the attachment 30 for a crayfish trap is attached to a cage trap 10 having a funnel-shaped portion 21 and an entry port 22 on both sides of the cage body 11, but this is not limited to this, and the attachment 30 for a crayfish trap may be attached to a cage trap 10 having a funnel-shaped portion 21 and an entry port 22 only on one end of the cage body 11, and the configuration of the cage trap 10 may be any as long as it can be attached.

[0057] In addition, in the embodiment, the sheet 31 is translucent or opaque, but it is not limited to this and it is also possible to use a transparent sheet 31. In addition, in the embodiment, the sheet 31 is made of synthetic resin, but it is not limited to this and it may be made of other materials such as rubber as long as it can be formed into a cylindrical shape.

[0058] That is, the present invention is not limited to the examples as long as the functions and effects of the present invention are exhibited. [Industrial Applicability]

[0059] The present invention is suitable for use as an attachment for modifying a conventional commercially available fish and shellfish trap to capture crayfish. [Explanation of symbols]

[0060] 10. Cage trap 11... Basket body 12... Frame 13…net 14… Capture room 15... Removal port 19... Retention cord 21… funnel-shaped part 22... Entry point 23... Pull cord 30... Crayfish trap attachment 31... Seat 32... Pitfall 33...End 34... Connecting member (hook) 35... Edge 40... Crayfish

Claims

1. A crayfish trap attachment for attaching to a cage trap for capturing crayfish, the attachment comprising: a cage body having a net stretched over a frame and a capture chamber formed therein; a funnel-shaped portion that narrows in diameter from the end of the cage body toward the inside and communicates with the capture chamber through an entrance; and an outlet that is openably and closably provided on the cage body and allows captured crayfish to be removed; A flexible rectangular sheet, a hole provided in the sheet through which the crayfish falls, and a connecting member provided at a pair of ends of the sheet and connecting the ends of the sheet rolled into a cylindrical shape, The sheet can be inserted into and removed from the capture chamber through the removal port, and the sheet is rolled into a cylindrical shape and the edge of the sheet is connected to the entrance by overlapping it with the connecting member, and the drop hole is positioned facing downward, making the sheet detachably attached to the cage trap.

2. 2. The attachment for a crayfish trap according to claim 1, The attachment for a crayfish trap is characterized in that the connecting members are resin hooks, and multiple hooks are provided at a pair of ends of the sheet.

3. 3. The attachment for a crayfish trap according to claim 1 or 2, The seat is made of synthetic resin and is formed in a rectangular shape, with a length L1 in the front-rear direction of the seat being 30 cm and a length L2 in the width direction of the seat being 26 cm. The attachment for a crayfish trap is characterized in that the hole is formed in a rectangular shape, with a length L3 in the front-to-back direction of the hole being 9 cm and a length L4 in the width direction of the hole being 9 cm.

4. 3. The attachment for a crayfish trap according to claim 1 or 2, The sheet is made of polyester or polypropylene and has a thickness of 0.3 mm or more and 0.6 mm or less.

5. 3. The attachment for a crayfish trap according to claim 1 or 2, An attachment for a crayfish trap, wherein the sheet is translucent or opaque.

6. 3. The attachment for a crayfish trap according to claim 1 or 2, The cage trap has two opposing funnel-shaped portions that decrease in diameter from opposing ends of the cage body toward the inside and communicate with the capture chamber through the inlet, An attachment for a crayfish trap, characterized in that the sheet is attached so that the edges on both sides of the sheet rolled into a cylindrical shape overlap the entrances of the opposing funnel-shaped portions.

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