Natural propagation method and application of Yangtze sturgeon in open waters

Abstract

The present invention belongs to the field of Yangtze sturgeon breeding, and discloses a method and application of natural breeding of Yangtze sturgeon in open waters. The present invention, for the first time, practices the transformation and reconstruction of Yangtze sturgeon spawning grounds from the perspective of engineering implementation, proves the feasibility of repairing and transforming Yangtze sturgeon spawning grounds, realizes the natural breeding of Yangtze sturgeon in open waters, is a breakthrough research result of Yangtze sturgeon, and lays a solid foundation for the restoration of Yangtze sturgeon habitats.

Description

Technical Field

[0001] The invention belongs to the field of Yangtze sturgeon breeding, and in particular relates to a natural breeding method and application of Yangtze sturgeon in open waters. Background Art

[0002] In July 2022, the World Conservation Union (IUCN) announced the extinction of the Yangtze River sturgeon in the wild. The success of the wild regulated reproduction experiment of the Yangtze River sturgeon in 2023 provided a new idea for the restoration of the natural population of the Yangtze River sturgeon, but there is still a lack of methods for implementation in open waters. However, in order to effectively support the reconstruction of the Yangtze River sturgeon population, it is necessary to implement spawning ground restoration and reconstruction in open waters. On the basis of the success of the experiment in 2023, the applicant conducted practical research on the methods of restoration and reconstruction of the spawning grounds of the Yangtze River sturgeon in open waters, and finally achieved success in the spawning ground transformation and reproduction experiment in open waters in 2024. In practice, when we used the parameters previously published in the restricted water environment "Wild Reproduction Methods and Applications of Yangtze River Sturgeon in Natural Waters" and the indoor test environment "The silver lining in rewilding the vanished sturgeon in the Yangtze River", although some reproduction behaviors such as the top flow of the Yangtze River sturgeon were triggered, the reproduction of the Yangtze River sturgeon was not successfully induced. Therefore, we optimized and adjusted the relevant parameters, and finally successfully induced the Yangtze River sturgeon to reproduce successfully in open waters.

[0003] At present, most of the research on the restoration of the Yangtze sturgeon habitat remains in the theoretical stage. For the first time, we have achieved the formation of spawning grounds suitable for the reproduction of Yangtze sturgeon by finding and transforming the natural environment, and based on this, we have summarized the natural reproduction method of Yangtze sturgeon in open waters. Summary of the invention

[0004] The purpose of the invention is to provide a natural propagation method of Yangtze sturgeon in open waters.

[0005] Another object of the present invention is to provide an application of a natural reproduction method of Yangtze sturgeon in open waters to the natural reproduction of Yangtze sturgeon.

[0006] In order to achieve the above object, the present invention adopts the following technical measures:

[0007] A method for natural reproduction of Yangtze sturgeon in open waters, comprising:

[0008] 1. During the breeding season of Yangtze sturgeon, a river with a water temperature of 15-21℃ is selected as the test area, and the area with a gentle slope-pond structure in the test area is used as the field spawning ground; the narrowest part of the spawning ground is ≥10 meters, the slope of the gentle slope is 2° to 5°, the height difference between the pond and the surrounding bottom is ≥0.5m, and the pond area is ≥4m2; the flow rate of the river is ≤1.3m / s; the area of ​​the gentle slope-pond structure is ≥100 square meters;

[0009] The head of the water area of ​​the test area is equipped with a dam or a barrier net, the tail is equipped with a barrier net, and the ratio of the water area to the spawning ground area is ≥1;

[0010] 2. In March and April when Yangtze sturgeon are breeding, water flow modification was carried out in the selected gentle slope-pond structure; a flow rate controller was set at the upstream of the gentle slope to keep the flow rate at the gentle slope at 0.5-1.3m / s, and the rear end of the gentle slope had turbulent characteristics, and the position and angle of the water pump were adjusted to ensure that the model simulated vertical vorticity was between 0.005-0.3s -1 between;

[0011] 3. Lay clean pebbles of 10-20cm in size on the gentle slope and pond area;

[0012] 4. Place multiple underwater cameras in the spawning area to observe and evaluate the response of broodstock to the spawning grounds and their reproduction in real time.

[0013] In the method described above, preferably, the water flow modification method in step 2) includes: using a Doppler flow profiler to measure the flow field, and using MIKE3 three-dimensional water simulation software to establish a hydrodynamic model based on the underwater topography and flow field.

[0014] In the method described above, preferably, the flow rate controller is a water pump.

[0015] The protection scope of the present invention also includes:

[0016] Application of the above method in the natural reproduction of Yangtze sturgeon.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. The present invention realizes the natural reproduction of Yangtze sturgeon in open water for the first time, which is a breakthrough research result of Yangtze sturgeon and lays a solid foundation for the restoration of Yangtze sturgeon habitat.

[0019] 2. The present invention is the first to practice the transformation and reconstruction of the Yangtze River sturgeon spawning ground from the perspective of engineering implementation, proving the feasibility of repairing and transforming the Yangtze River sturgeon spawning ground.

[0020] 3. During the experiment, a joint underwater topographic survey was conducted using drones and Doppler profiler current meters, which can quickly obtain the bottom elevation of the water area.

[0021] 4. A hydrodynamic model was constructed to simulate various flow-making layout scenarios and obtain a more ideal layout method.

[0022] 5. For the first time, the spawning ground transformation comprehensively considered the large-scale ponds and gentle slope structures and the small-scale slopes, flow rates and pebble bottoms.

[0023] 6. In seasons with low water levels, river topography surveys can provide more accurate underwater topography. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The river section terrain conditions selected for Example 1 of the present invention.

[0025] Figure 2 Different water flow creation schemes simulated by MIKE3 3D water simulation software.

[0026] Figure 3 Example 1 successfully achieved the natural reproduction of the Yangtze sturgeon. DETAILED DESCRIPTION

[0027] In order to facilitate those skilled in the art to understand and implement the present invention, the present invention is further described in detail below in conjunction with embodiments. It should be understood that the implementation examples described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0028] Embodiment 1:

[0029] The spawning site established in the embodiment of the present invention is located in the Jiajiang waters of Jiang'an County, Yibin City, Sichuan Province

[0030] A method for natural reproduction of Yangtze sturgeon in open waters, comprising:

[0031] 1. In this embodiment, the Jiajiang River section of Zhudao, Jiang'an County, Yibin City was selected, and drone mapping was carried out when the water level was low in winter, and the river topography was surveyed using a level and a Doppler current profiler when the water level was high during the test. The head of the test area was a water dam, and the tail was blocked to form a test water area;

[0032] During the breeding season of Yangtze sturgeon, the water temperature in this area is between 15-21℃.

[0033] In this embodiment, the specific method of terrain survey is as follows: select ground benchmark points (multiple benchmark points can be used if the river section is long), and mark the benchmark point area for drone image positioning; measure the elevation difference every 20 meters along the river; the drone surveys the area to form a DSM (digital surface model); extract the elevation value of the benchmark point area; convert the elevation value of each measuring point; convert the water depth measured by the Doppler current profiler into an elevation value according to the river section; extract the drone DSM value points; and use irregular triangulation interpolation to form the river elevation together with the data points where the water depth measured by the Doppler current profiler is converted into elevation values. Figure 1 The topographic conditions of the river section selected by the present invention are displayed.

[0034] 2. In the test waters, select a gentle slope (2° to 5°) with a pond (the height difference between the pond and the surrounding bottom is greater than or equal to 0.5m, and the pond area is greater than or equal to 4m 2 ) area, that is, a gentle slope-pond structure, as a wild spawning ground, the narrowest part of the spawning ground is greater than or equal to 10 meters; a dam is set at the head of the gentle slope-pond water area, and a fence is set at the tail. The area of ​​the wild spawning ground is about 150 square meters, and the water area of ​​the fenced river section is more than 20,000 square meters. The ratio of the water area to the spawning ground area is ≥133:1.

[0035] 3. In March and April when the Yangtze River sturgeon reproduces, the Doppler current profiler is used to measure the flow field in the selected area. Based on the underwater topography and flow field, the MIKE3 three-dimensional water simulation software is used to establish a hydrodynamic model (including spatial discretization of the study area, generation of grid calculation units, elevation data used to define the topographic characteristics of each calculation unit, setting the initial water level and water flow and other states according to the flow field measurement results, and defining boundary conditions. The model roughness coefficient, friction coefficient and other parameters are calibrated and verified using measured data to complete the hydrodynamic modeling). By comparing different water flow creation scenarios, the appropriate water flow creation scheme is selected to keep the flow velocity at the gentle slope at 0.5-1.3m / s, and the rear end of the gentle slope has turbulent characteristics, ensuring that the model simulates the vertical vorticity at 0.005-0.3s -1 between. Figure 2 A and B show different water flow creation schemes. In this embodiment, scheme B is selected. On the one hand, the negative slope in scheme A is larger. On the other hand, the area where the flow field velocity reaches more than 0.5m / s in scheme A is relatively small, and no significant turbulence is formed.

[0036] 4. Gentle slope - The area where the pond is located is laid with clean pebbles of 10-20 cm in size.

[0037] 5. Place multiple underwater cameras in the spawning area to observe and evaluate the response of parent fish to the spawning area and their reproduction status in real time.

[0038] 6. Using a B-ultrasound machine, we selected Yangtze sturgeon broodstock that had developed to stage V. A total of 62 broodstock were put into the breeding stock, with a male-female ratio of 1:1.

[0039] 7. After the broodstock are put in, the water flow size is adjusted by the frequency converter. The water flow is adjusted to the target flow size within 1-2 hours, that is, the flow velocity in the front of the flow area reaches 0.5-1.3m / s.

[0040] Before the formal adjustment, the flow field conditions under different frequency changes of the frequency converter were measured by using a Doppler profile flowmeter; in addition, the broodstock were in the head flow for a long time and were closer to the outlet, which could also increase the water flow.

[0041] 8. Underwater cameras were used to observe the reproduction of broodstock in the spawning grounds and the successful reproduction ( Figure 3 Middle A), divers collected fertilized eggs, incubated them artificially, and successfully emerged ( Figure 3 (middle B).

Claims

1. A method for natural reproduction of Yangtze sturgeon in open waters, comprising: (1) During the breeding season of Yangtze sturgeon, a river with a water temperature of 15-21°C was selected as the test area, and an area with a gentle slope-pond structure in the test area was used as a field spawning site; the narrowest part of the spawning site was ≥10 meters, the gentle slope was 2° to 5°, the height difference between the pond and the surrounding bottom was ≥0.5m, and the pond area was ≥4m 2 ; The water velocity of the river is ≤1.3m / s, and the vertical vorticity is 0.005-0.3 s -1 Between; the area of ​​gentle slope-pond structure ≥ 100 square meters; The ratio of the water area to the spawning ground area is ≥ 1; (2) During the period of March and April when Yangtze sturgeon are breeding, water flow modification is carried out at the selected gentle slope-pond structure; a flow rate controller is installed upstream of the gentle slope so that the flow rate at the gentle slope is maintained at 0.5-1.3 m / s, and the rear end of the gentle slope has turbulent flow characteristics; (3) Lay clean pebbles of 10-20 cm in size on the gentle slope and pond area; (4) Multiple underwater cameras are deployed in the spawning area to observe and evaluate the response of parent fish to the spawning area and their reproduction status in real time.

2. The method according to claim 1, characterized in that The water flow modification method in step 2 includes: using a Doppler current profiler to measure the flow field, and using MIKE3 three-dimensional water simulation software to establish a hydrodynamic model based on the underwater topography and flow field.

3. The method according to claim 1, characterized in that The flow rate controller is a water pump.

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