A device for collecting fry and juvenile fish in the main stream of the Yellow River

Abstract

The application discloses a device for collecting fry and juvenile fish in the main stream of the Yellow River, which comprises a collecting head, a collecting box, a drainage end and a support, the left and right sides of the collecting box are respectively provided with the collecting head and the drainage end, and the collecting box is further provided with the support, the collecting head is a conical cylinder, the large end of the conical cylinder is provided with a multi-hole conical cover which is gathered away from the conical cylinder, the small end of the conical cylinder is communicated with a water inlet pipe of the collecting box, the drainage end is a drainage pipe on the collecting box opposite to the water inlet pipe, a flowmeter and an axial flow pump are arranged on the end of the drainage pipe away from the collecting box, the collecting box is provided with a one-way self-closing structure and a fry and juvenile fish filtering conical cylinder corresponding to the water inlet pipe and the drainage pipe, and the fry and juvenile fish filtering conical cylinder is provided with an induction cylinder on the front and back sides. The device is used for collecting fry and juvenile fish in an active way, and the food induction cylinder is arranged in the collecting box to attract the fry and juvenile fish to stay, so that the fry and juvenile fish can be efficiently collected, and the fish quality resources in the main stream of the Yellow River can be conveniently and quickly monitored.

Description

Technical Field

[0001] This invention relates to the technical field of fishery resource collection equipment, and in particular to a device for collecting juvenile and young fish in the main stream of the Yellow River. Background Technology

[0002] The Yellow River, the second longest river in my country, has a vast basin with numerous mountains and significant east-west elevation differences, resulting in considerable variations in landforms across different regions. Furthermore, because the Yellow River basin is located in the mid-latitudes, it is subject to complex influences from atmospheric and monsoon circulation, leading to significant climatic differences between different areas within the basin. The section of the Yellow River in Shandong Province, being the last section before the river flows into the sea, benefits from timely fish monitoring to understand the overall water quality of the Yellow River. Monitoring the number of juvenile and young fish in this section of the main stream allows for the determination of survival rates during the early life stages of fish, effectively inferring the annual replenishment of fish populations, and consequently, determining changes in fish population size and age structure. Currently, the main equipment for collecting juvenile and larval fish includes a collection head, a collection box, a drain, and a support. The collection box is used to filter and collect the juveniles and larvae. The left and right sides of the collection box are equipped with a collection head for gathering the juveniles and larvae from the external water body and a drain for draining the water from the collection box. The collection box also has a support for relatively fixing it in the water body. Overall, the collection time is long and the collection efficiency is low, which restricts the increase in monitoring frequency and makes it difficult to promptly determine changes in the water quality of the Yellow River main stream and changes in the survival status of fish within it, resulting in a lag in relevant protection policies. Based on this need, we have specially designed a juvenile and larval fish collection device that can actively generate negative pressure, shortening the collection time and improving the collection efficiency, so as to promptly determine the number of juvenile and larval fish in this section of the Yellow River main stream and better provide a basis for formulating Yellow River protection policies. Summary of the Invention

[0003] To address the aforementioned existing problems, this invention provides a fish larvae and juveniles collection device for the Yellow River main stream. The device actively collects the larvae and juveniles by suction, and a food-attracting tube is set up in the collection box to attract the larvae and juveniles to stay. This device can efficiently collect the larvae and juveniles and conveniently and quickly monitor the fish resources of the Yellow River main stream.

[0004] The technical solution of this invention is as follows:

[0005] This invention provides a device for collecting juvenile and young fish in the main stream of the Yellow River, comprising a collection head, a collection box, a drain end, and a support. The collection box is used to filter and collect the juvenile and young fish. The left and right sides of the collection box are respectively provided with a collection head for gathering and collecting the juvenile and young fish from external water and a drain end for draining water from the collection box. The collection box is also provided with a support for relatively fixing it in the water. The collection head is a conical cylinder, with a porous conical shroud at the large end of the conical cylinder that gathers the fish away from the conical cylinder. The small end of the conical cylinder is connected to the water inlet pipe of the collection box. The drain end is a drain pipe on the collection box opposite to the water inlet pipe, with sequentially arranged... The system includes a flow meter and an axial flow pump. The collection box comprises an inner box and an outer box. The inner box is embedded in the outer box from top to bottom. Locking bolts are provided on the left and right sides of the upper end of the outer box. The locking bolts are threaded into the upper end of the inner box to lock the inner box and the outer box together. The inlet pipe and the outlet pipe are respectively provided on the left and right side walls of the outer box. The inner wall of the inner box is provided with a one-way self-closing structure and a juvenile fish filter cone corresponding to the inlet pipe and the outlet pipe. Vertical insertion seats are provided on the inner walls of the inner box on the front and rear sides of the juvenile fish filter cone. An induction tube for attracting juvenile fish to stay for food is embedded in the vertical insertion seat from top to bottom.

[0006] Furthermore, the axes of the inlet pipe, the juvenile fish filter cone, and the outlet pipe are on the same straight line.

[0007] Furthermore, the juvenile fish filter cone includes a fine filter screen, a cone tip block, and a cone frame. The cone frame has a polyhedral cone structure and its axis is on the same straight line as the axis of the drain pipe. The cone frame is composed of multiple ribs with one end converging to form a tip. A fine filter screen is provided between two adjacent ribs of the cone frame to prevent juvenile fish from escaping into and out of the drain pipe. A cone tip block is provided at the tip of the cone frame facing the one-way self-closing structure.

[0008] Furthermore, a connecting block is nested on the cone tip block. The end of the connecting block away from the cone tip block is provided with a support bent rod evenly distributed around the unidirectional self-closing structure. The end of the support bent rod away from the connecting block is provided with a connecting ring that presses against the inner wall of the left side of the inner box. Several tightening bolts are threaded into the connecting ring. The tightening bolts push the connecting ring away from the inner wall of the left side of the inner box, so that the end of the juvenile fish filter cone near the drain pipe is pressed tightly against the inner wall of the right side of the inner box.

[0009] Furthermore, the one-way self-closing structure includes an inclined tube and a hinged baffle. The inclined tube has a tubular structure and the end away from the water inlet pipe is inclined from top to bottom. The upper side of the end of the inclined tube away from the water inlet pipe is hinged to a hinged baffle for sealing the end of the inclined tube from top to bottom by its own weight.

[0010] Furthermore, the vertical insertion seat includes a connecting plate, a nesting ring, and an annular groove. The connecting plate is horizontal and one end is fixedly mounted on the inner wall of the inner box. The end of the connecting plate away from the inner wall of the inner box is provided with a nesting ring. The axis of the nesting ring is vertical and the upper end is provided with a concentric annular groove. The annular groove is used to nest in the lower end of the induction tube from top to bottom.

[0011] Furthermore, the induction tube includes an upper inner ring, an annular cavity, an upper outer ring, an inner support, an inner filter, an outer filter, an outer support, and an embedded bottom ring. The embedded bottom ring is used to embed into the annular groove of the vertical insertion seat. An upper inner ring and an upper outer ring are respectively provided above the embedded bottom ring. The upper outer ring is nested outside the upper inner ring. Multiple evenly distributed outer supports are provided between the lower end of the upper outer ring and the embedded bottom ring. An outer filter is provided between two adjacent outer supports. Similarly, multiple evenly distributed inner supports are provided between the lower end of the upper inner ring and the embedded bottom ring. An inner filter is provided between two adjacent inner supports. The inner filter and the outer filter form an annular cavity for placing food for fry. Both the inner filter and the outer filter are made of the same material and the same size mesh.

[0012] Furthermore, the bracket includes an outer sleeve, a support block, a plug rod, a locking bolt, and support legs. Support legs are provided at the four vertical edges of the outer casing. An outer sleeve is provided on the side wall of the support leg away from the outer casing. A plug rod is embedded in the outer sleeve. A support block is nested on the part of the plug rod at the lower end of the support leg. The support block rests against the lower end of the corresponding support leg. A locking bolt for locking the support block onto the plug rod is horizontally embedded on the support block.

[0013] Furthermore, the drain port of the axial flow pump is at the same horizontal plane as the lower end of the support leg.

[0014] Furthermore, each of the four corners at the upper end of the outer casing is provided with a lifting arm, and the lifting arm is provided with a lifting hole for the outer casing.

[0015] Because the present invention employs the above-mentioned technology, its specific positive and beneficial effects compared with the prior art are as follows:

[0016] 1. In order to improve the collection efficiency of juvenile fish in the main stream of the Yellow River, this invention specifically sets up an axial flow pump at the drainage end of the collection box to generate negative pressure in the collection box, which effectively avoids the problem of damage to juvenile fish caused by directly pumping water into the collection box, and facilitates the later release.

[0017] 2. In this invention, a conical tube is specially designed as the collection head before the water flows into the collection box. The large end of the conical tube opens in a direction away from the collection box. The large end of the conical tube is provided with a multi-hole conical cover that converges away from the conical tube. The multi-hole conical cover is made of hard plastic and has a through hole for preventing debris on the conical surface. The diameter of the through hole is 10mm-30mm, which mainly prevents larger particles of sand, gravel and branches and other debris from entering the conical tube.

[0018] 3. In this invention, a flow meter is installed between the drainage pipe and the axial flow pump. The axial flow pump is powered by a lithium battery pack on the shore or bridge. The flow meter and the axial flow pump are electrically connected to a controller placed together with the lithium battery pack. The controller determines the total amount of water passing through the collection box by the water flow detection signal of the flow meter. After the collection is completed, the distribution of juvenile fish in the nearby waters can be estimated by checking the number of juvenile fish in the collection box. Compared with collecting juvenile fish by towing the collection box by boat, the estimation accuracy is higher.

[0019] 4. In order to facilitate the removal of the collected juvenile fish later, the present invention sets up a collection box including an inner box and an outer box. The outer box is connected to the support, and the inner box is embedded in the outer box and can be relatively detached. This makes it convenient to extract the juvenile fish after collection. That is, the inner box can be disassembled from the outer box and lifted out, which is convenient and quick. If multiple fixed-point collections are required, there is no need to remove the outer box, axial flow pump and support from the water.

[0020] 5. In order to filter out the larvae and juveniles in the inner tank and avoid damage to them, the present invention provides a cone-shaped filter cone for larvae and juveniles at the connection between the inner tank and the drain pipe, so that the larvae and juveniles can leave the water flow and stay in the water body on the front and back sides of the inner tank where the flow velocity is lower.

[0021] 6. In order to securely and detachably fix the juvenile fish filter cone in the inner box, this invention does not use bolts to directly install it on the right inner wall of the inner box. Instead, a sleeve block is nested on the cone tip block. The end of the sleeve block away from the cone tip block is provided with a support rod evenly distributed around the one-way self-closing structure. The end of the support rod away from the sleeve block is provided with a connecting ring that presses against the left inner wall of the inner box. Several tightening bolts are threaded into the connecting ring. The tightening bolts push the connecting ring away from the left inner wall of the inner box, so that the end of the juvenile fish filter cone near the drain pipe is pressed tightly against the right inner wall of the inner box. In this way, the entire juvenile fish filter cone is detachably fixed by supporting the left and right side walls of the inner box.

[0022] 7. To prevent juvenile fish from escaping through the inlet pipe after the axial flow pump stops, thus affecting monitoring accuracy, this invention provides a one-way self-closing structure on the inner wall of the inner box corresponding to the inlet pipe. The one-way self-closing structure includes an inclined tube and a hinged baffle. The inclined tube is tubular and its end away from the inlet pipe is inclined from top to bottom. The upper side of the end of the inclined tube away from the inlet pipe is hinged to a hinged baffle for sealing the end of the inclined tube from top to bottom using its own weight. After the collection is completed, the negative pressure generated in the collection box disappears when the axial flow pump stops, and the hinged baffle falls back under its own weight and seals the inclined tube, thus preventing juvenile fish from escaping from the collection box.

[0023] 8. In order to better attract fry to stay, the present invention provides vertical insertion seats on the inner walls of the inner box on both sides of the fry filter cone, and an induction tube for food-induced fry to stay is embedded in the vertical insertion seat from top to bottom.

[0024] 9. The present invention sets the induction tube as a cylindrical structure with inner and outer filter screens, and an annular cavity between the inner and outer filter screens. The fry can eat the fish food in the annular cavity through the inner and outer filter screens. This can not only prevent too much fish food from escaping into the water in the inner tank, thus saving fish food and preventing it from being carried away by the water flow in the inner tank, but also make it convenient for the fry to eat and attract them to stay in the inner tank. Attached Figure Description

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

[0026] Figure 2 This is the front view of the present invention;

[0027] Figure 3 This is the right view of the present invention;

[0028] Figure 4 This is a schematic diagram of the structure of the data collection box of the present invention;

[0029] Figure 5 yes Figure 4 Top view of the structure shown;

[0030] Figure 6 yes Figure 5 Sectional view at point AA;

[0031] Figure 7 yes Figure 4 A schematic diagram of the structure shown after removing the box cover;

[0032] Figure 8 yes Figure 7 A schematic diagram of the inner box after removing the induction tube in the structure shown;

[0033] Figure 9yes Figure 8 A magnified view of a portion of point B in the middle;

[0034] Figure 10 This is a schematic diagram of the structure of the induction tube of the present invention;

[0035] Figure 11 yes Figure 7 The diagram shows the structure of the outer casing.

[0036] In the diagram: 1-Box cover, 2-Handle elongated hole, 3-Inner box lifting hole, 4-Outer box lifting hole, 5-Lifting cantilever, 6-Outer box body, 7-Drain pipe, 8-Flow meter, 9-Axial flow pump, 10-Outer sleeve, 11-Support block, 12-Insertion rod, 13-Locking bolt, 14-Inner box body, 15-Inlet pipe, 16-Connecting pipe, 17-Conical cylinder, 18-Perforated conical shroud, 19-Support leg, 20-Upper frame, 21-Inducing cylinder, 22-Fine filter screen, 23-Conical frame, 2 4-Embedded ring, 25-Conical tip block, 26-Socket block, 27-Supporting bent rod, 28-Tightening bolt, 29-Connecting ring, 30-Sloping tube, 31-Hinged baffle, 32-Drain hole, 33-Connecting plate, 34-Nested ring, 35-Annular groove, 36-Locking bolt, 210-Upper inner ring, 211-Annular cavity, 212-Upper outer ring, 213-Inner support, 214-Inner filter screen, 215-Outer filter screen, 216-Outer support, 217-Embedded bottom ring. Detailed Implementation

[0037] Example 1:

[0038] like Figures 1-11As shown, this invention provides a device for collecting juvenile and young fish in the main stream of the Yellow River. Based on existing technology, to improve collection efficiency, an axial flow pump 9 is specifically installed at the drainage end of the collection box to generate negative pressure inside the box. This effectively avoids the problem of damage to juvenile and young fish caused by directly pumping water into the collection box, facilitating later release. Simultaneously, a conical cylinder 17 is specially designed as the collection head. The large end of the conical cylinder 17 opens away from the collection box. The large end of the conical cylinder 17 has a porous conical cover 18 that converges away from the conical cylinder 17. The porous conical cover 18 is made of rigid plastic and has through holes on its conical surface to prevent debris from entering. The diameter of these holes is 10mm-30mm, primarily preventing larger particles of sand, gravel, branches, and other debris from entering the conical cylinder 17. The small end of the conical cylinder 17 has a connecting pipe 16, which is connected to the water inlet pipe 15 of the collection box via a flange, draining... The water end is the drain pipe 7 on the collection box, which is opposite to the inlet pipe 15. The end of the drain pipe 7 away from the collection box is connected to a flow meter 8 by a flange. The end of the flow meter 8 away from the drain pipe 7 is connected to an axial flow pump 9 by a flange. In this way, the axial flow pump 9 generates negative pressure in the collection box. The water flow carries the juvenile fish through the holes of the porous cone shroud 18 and passes through the cone 17, the connecting pipe 16, the inlet pipe 15, the collection box, the drain pipe 7, the flow meter 8 and the axial flow pump 9 in sequence. Finally, it is discharged by the axial flow pump 9. Compared with the collection efficiency of juvenile fish generated by natural water flow, the collection efficiency is significantly improved. The axial flow pump 9 is powered by a lithium battery pack on the shore or bridge. The flow meter 8 and the axial flow pump 9 are electrically connected to a controller placed together with the lithium battery pack. The controller determines the total amount of water passing through the collection box by the water flow detection signal of the flow meter 8. After the collection is completed, the distribution of juvenile fish in the nearby water area can be estimated by checking the number of juvenile fish in the collection box.

[0039] To facilitate the removal of the collected juvenile fish later, the collection box includes an inner box 14 and an outer box 6. The inner box 14 is embedded in the outer box 6 from top to bottom. The upper end of the inner box 14 is fitted with and sealed with a box cover 1. The side wall of the inner box 14 corresponding to the box cover 1 also has elongated holes 2 for easy lifting later. The upper end of the outer box 6 has an upper frame 20. Locking bolts 36 are threaded horizontally on the left and right sides of the upper frame 20. The locking bolts 36 are also threaded into the upper end of the inner box 14, thus locking the inner box 14 and the outer box 6 together. The water inlet pipe 15 and the drain pipe 7 are respectively set on the left and right side walls of the outer box 6. The left inner wall of the inner box 14 has a one-way self-closing structure corresponding to the water inlet pipe 15. The right inner wall of the inner box 14 has a drain hole 32 corresponding to the drain pipe 7. The drain hole 32 faces inward of the inner box 14. A connecting ring 29 is fixedly installed at the edge of the part, and a juvenile fish filter cone is nested on the connecting ring 29. The juvenile fish filter cone includes a fine filter screen 22, a cone tip block 25, and a cone frame 23. The cone frame 23 has a polyhedral cone structure and its axis is on the same straight line as the axis of the drain pipe 7. The cone frame 23 is composed of multiple ribs with one end gathered together to form a tip. A fine filter screen 22 is provided between two adjacent ribs of the cone frame 23 to isolate juvenile fish from escaping into the drain pipe 7. The mesh diameter of the fine filter screen 22 is 3mm-5mm. A cone tip block 25 is provided at the tip of the cone frame 23 facing the one-way self-closing structure. In this way, after the water flow carries the juvenile fish into the inner box 14 from the one-way self-closing structure, in order to avoid harming the juvenile fish, a cone-shaped juvenile fish filter cone is specially designed so that the juvenile fish can leave the water flow and stay in the water body on the front and back sides of the inner box 14 where the flow velocity is smaller.

[0040] In order to securely and detachably fix the juvenile fish filter cone inside the inner box 14, instead of using bolts to directly install it on the right inner wall of the inner box 14, a sleeve block 26 is nested on the cone tip block 25. The end of the sleeve block 26 away from the cone tip block 25 is provided with a support bent rod 27 evenly distributed around the one-way self-closing structure. The end of the support bent rod 27 away from the sleeve block 26 is provided with a connecting ring 29 that presses against the left inner wall of the inner box 14. Several tightening bolts 28 are threaded into the connecting ring 29. The tightening bolts 28 push the connecting ring 29 away from the left inner wall of the inner box 14, so that the end of the juvenile fish filter cone near the drain pipe 7 is pressed tightly against the right inner wall of the inner box 14.

[0041] To better attract fry and young fish to stay, vertical insertion seats are provided on the inner walls of the inner box 14 on both sides of the fry and young fish filter cone. An induction tube 21 for food-induced fry and young fish to stay is embedded in the vertical insertion seat from top to bottom. The vertical insertion seat includes a connecting plate 33, a nesting ring 34 and an annular groove 35. The connecting plate 33 is horizontal and one end is fixed on the inner wall of the inner box 14. The end of the connecting plate 33 away from the inner wall of the inner box 14 is provided with a nesting ring 34. The axis of the nesting ring 34 is vertical and the upper end is provided with a concentric annular groove 35. The annular groove 35 is used to nest from top to bottom at the lower end of the induction tube 21, so that the fry and young fish can eat food from the inner and outer walls of the induction tube 21.

[0042] The induction tube 21 includes an upper inner ring 210, an annular cavity 211, an upper outer ring 212, an inner support 213, an inner filter 214, an outer filter 215, an outer support 216, and an embedded bottom ring 217. The embedded bottom ring 217 is used to embed into the annular groove 35 of the vertical insertion seat. The upper inner ring 210 and the upper outer ring 212 are respectively provided above the embedded bottom ring 217. The upper outer ring 212 is nested outside the upper inner ring 210. A plurality of evenly distributed outer supports 216 are provided between the lower end of the upper outer ring 212 and the embedded bottom ring 217. Adjacent outer supports An outer filter screen 215 is provided between the frames 216, while multiple evenly distributed inner supports 213 are provided between the lower end of the upper inner ring 210 and the embedded bottom ring 217. An inner filter screen 214 is provided between two adjacent inner supports 213. An annular cavity 211 for placing food for fry and young fish is formed between the inner filter screen 214 and the outer filter screen 215. The inner filter screen 214 and the outer filter screen 215 are both made of the same material and the same size mesh. The fry and young fish feed inside the ring structure formed by the inner filter screen 214 or outside the ring structure formed by the outer filter screen 215.

[0043] The one-way self-closing structure includes an inclined tube 30 and a hinged baffle 31. The inclined tube 30 has a tubular structure and the end away from the water inlet pipe 15 is inclined from top to bottom. The upper side of the end of the inclined tube 30 away from the water inlet pipe 15 is hinged with a hinged baffle 31 for using its own weight to cover the end of the inclined tube 30 from top to bottom. In this way, after the collection is completed, the axial flow pump 9 stops and the negative pressure generated in the collection box disappears. The hinged baffle 31 falls back under its own weight and covers the inclined tube 30 to prevent the juvenile fish from escaping from the collection box.

[0044] To ensure that low-flow-rate areas for storing fry are created on the front and rear sides of the inner tank 14, the axes of the inlet pipe 15, the inclined pipe 30, the fry filter cone, and the drain pipe 7 are aligned on the same straight line.

[0045] In order to deploy the collection box into the water body, a lifting arm 5 is provided at the four corners of the upper end of the outer box 6. The lifting arm 5 is provided with an outer box lifting hole 4. In order to facilitate the inner box 14 to hook out the outer box 6, an inner box lifting hole 3 is provided at the four corners of the inner box 14.

[0046] The drainage port of the axial flow pump 9 is set to be at the same level as the lower end of the support leg 19 so that the collection box can be placed stably when it is hoisted and placed on the ground.

[0047] The support system is divided into shallow support systems for fixing the collection box in shallow water areas near the shore and attachment support systems for fixing the collection box under a floating bridge or bridge arch, depending on the purpose. The shallow support system includes an outer sleeve 10, a support block 11, a rod 12, a locking bolt 13, and support legs 19. Support legs 19 are provided at the four vertical edges of the outer casing 6. The outer sleeve 10 is provided on the side wall of the support leg 19 away from the outer casing 6. The rod 12 is embedded in the outer sleeve 10. The rod 12 is located at the lower end of the support leg 19. Partially nested with support blocks 11, the support blocks 11 rest against the lower end of the corresponding support legs 19, and horizontally embedded with locking bolts 13 for locking the support blocks 11 onto the insertion rod 12, so that the outer box 6 can be adjusted up and down along the insertion rod 12. Generally, the water surface is set to submerge the drain pipe 7 and the water inlet pipe 15, and the upper end of the induction cylinder 21 extends out of the water surface, that is, the conical cylinder 17 draws water from a water layer of about 10cm below the water surface, so as to ensure that the axial flow pump 9 can generate good negative pressure in the collection box;

[0048] The attachment support includes steel cables and hooks. The four hooks are respectively hooked onto the corresponding outer box lifting holes 4. The upper ends of the four steel cables are respectively tied to the front and rear sides of the bridge, so that the upper ends of the four steel cables are distributed in a rectangle. The collection box is located at the center where the lower ends of the four steel cables converge, so that the collection box is placed in the bridge hole under the bridge deck.

Claims

1. A device for collecting juvenile and young fish in the main stream of the Yellow River, comprising a collection head, a collection box, a drain end, and a support, wherein the collection box is used to filter and collect the juvenile and young fish, and the left and right sides of the collection box are respectively provided with a collection head for gathering and collecting the juvenile and young fish from external water bodies and a drain end for draining the water in the collection box, and the collection box is also provided with a support for relatively fixing it in the water body, characterized in that: The collecting head is a conical cylinder. The large end of the conical cylinder has a porous conical shroud that converges away from the conical cylinder. The small end of the conical cylinder is connected to the inlet pipe of the collection box. The drain end is a drain pipe on the collection box opposite to the inlet pipe. A flow meter and an axial flow pump are sequentially installed on the end of the drain pipe away from the collection box. The collection box includes an inner box and an outer box. The inner box is embedded in the outer box from top to bottom. Locking bolts are respectively installed on the left and right sides of the upper end of the outer box. The locking bolts are threaded into the upper end of the inner box, locking the inner and outer boxes together. The inlet pipe and drain pipe are respectively located on the left and right side walls of the outer box. A one-way self-closing structure and a juvenile fish filter cone are respectively installed on the inner wall of the inner box corresponding to the inlet pipe and drain pipe. The filter cone for juvenile fish has vertical insertion seats on the inner walls of its front and rear sides. An induction tube for attracting juvenile fish to stay in the filter cone is embedded in each vertical insertion seat from top to bottom. The axes of the inlet pipe, the filter cone, and the outlet pipe are aligned. The filter cone includes a fine filter screen, a cone tip, and a cone frame. The cone frame has a polyhedral cone structure, and its axis is aligned with the axis of the outlet pipe. The cone frame is composed of multiple ribs that converge at one end to form a pointed tip. A fine filter screen is provided between two adjacent ribs of the cone frame to prevent juvenile fish from escaping into the outlet pipe. A cone tip is located at the tip of the cone frame facing the unidirectional self-closing structure. A connecting block is nested on the cone tip. The end of the connecting block away from the cone tip is... The system includes evenly distributed support rods around a one-way self-closing structure. The ends of these support rods away from the connecting block have connecting rings that press against the left inner wall of the inner chamber. Several tightening bolts are threaded into the connecting rings, which push the connecting rings away from the left inner wall of the inner chamber, causing the end of the juvenile fish filter cone near the drain pipe to press tightly against the right inner wall of the inner chamber. The one-way self-closing structure includes an inclined tube and a hinged baffle. The inclined tube is tubular, with the end away from the inlet pipe sloping downwards. A hinged baffle is hinged to the upper side of the end of the inclined tube away from the inlet pipe to seal the end of the inclined tube from top to bottom using its own weight. The vertical insertion seat includes a connecting plate, a nested ring, and an annular groove. The connecting plate is horizontal and one end is fixedly installed inside the inner chamber. On the inner wall of the housing, a nested ring is provided at the end of the connecting plate away from the inner wall of the housing. The axis of the nested ring is vertical and the upper end has a concentric annular groove. The annular groove is used to nest from top to bottom into the lower end of the induction cylinder. The induction cylinder includes an upper inner ring, an annular cavity, an upper outer ring, an inner support, an inner filter, an outer filter, an outer support, and an embedded bottom ring. The embedded bottom ring is used to embed into the annular groove of the vertical insertion seat. Above the embedded bottom ring are an upper inner ring and an upper outer ring, respectively. The upper outer ring is nested outside the upper inner ring. Between the lower end of the upper outer ring and the embedded bottom ring, there are multiple evenly distributed outer supports. An outer filter is placed between two adjacent outer supports. Similarly, between the lower end of the upper inner ring and the embedded bottom ring, there are multiple evenly distributed inner supports. An inner filter is placed between two adjacent inner supports.The inner and outer filter screens form an annular cavity for placing food for fry. Both the inner and outer filter screens are made of the same material and have the same mesh size.

2. The device for collecting juvenile and young fish in the main stream of the Yellow River according to claim 1, characterized in that: The bracket includes an outer sleeve, a support block, a plug rod, a locking bolt, and support legs. Support legs are provided at the four vertical edges of the outer casing. An outer sleeve is provided on the side wall of the support leg away from the outer casing. A plug rod is embedded in the outer sleeve. A support block is nested on the part of the plug rod at the lower end of the support leg. The support block rests against the lower end of the corresponding support leg. A locking bolt for locking the support block onto the plug rod is horizontally embedded on the support block.

3. The device for collecting juvenile and young fish in the main stream of the Yellow River according to claim 2, characterized in that: The drain port of the axial flow pump is at the same level as the lower end of the support leg.

4. The device for collecting juvenile and young fish in the main stream of the Yellow River according to claim 3, characterized in that: The outer casing is provided with lifting arms at the four corners of its upper end, and the lifting arms are provided with lifting holes for the outer casing.

Images