Method for calculating suitability degree of spawning site considering hatching capacity

Abstract

The invention discloses a spawning site suitability calculation method giving consideration to incubation capacity, which comprises the following steps: calculating spawning site suitability of a fish spawning period according to a habitat factor suitability curve of the fish spawning period, calculating the suitability of a drifting incubation period by considering time conditions required by roe drifting incubation on the basis of meeting the suitability of the spawning period, and calculating the spawning site suitability of the fish spawning period. The spawning site comprehensive suitability giving consideration to the hatching capacity is obtained through the combination of the two methods. According to the method, habitat factors in the fish spawning period and time conditions needed in the drifting hatching period are comprehensively considered, the spawning site suitability better meeting the requirements of fish spawning and hatching periods can be obtained, the requirements for indexes such as water depth, flow speed and water temperature in the fish spawning period are considered, and meanwhile the requirements for the spawning site suitability after fish spawning are also considered. Requirements of roe drifting incubation on water flow velocity and drifting distance are of great significance for more scientifically guiding selection of restoration positions of a fish spawning site.

Description

Technical Field

[0001] The invention relates to the technical field of ecohydraulics, and in particular to a method for calculating the suitability of a spawning ground taking into account hatching capacity. Background Art

[0002] As fish with relatively complete monitoring data in the upper reaches of the Yangtze River, drifting egg-laying fish are often used as indicator species. By analyzing the spawning time and spawning habitat of drifting egg-laying fish, regional ecological flow can be obtained. Ecological flow is an important basis for protecting the survival and reproduction of fish species. Therefore, studying the spawning habitat of drifting egg-laying fish is of great significance to maintaining regional fish habitats, protecting the survival of fish species, and protecting biodiversity.

[0003] The key life history of fish mainly includes the spawning and reproduction period (spawning period and hatching period), the migration period, and the wintering period. In the existing spawning ground research of fish that lay drifting eggs, the suitability of the spawning ground is based on the habitat characteristics during the spawning period. But in fact, since many rivers in my country have hydraulic structures such as dams, which reduce the continuity of fish egg drifting, many drifting fish eggs face the problem of insufficient drifting hatching time and distance, which makes the survival rate of fish during the spawning and hatching period generally very low, which directly affects the structure of fish populations. Therefore, a spawning ground suitability calculation method that takes into account hatching capacity is proposed, which can be used to determine the area in the river that can adapt to fish spawning and the area where the eggs produced can be effectively hatched, and provide technical support for finding fish spawning grounds and reasonably determining the location of spawning ground restoration.

[0004] In summary, the present invention provides a method for calculating the suitability of a spawning ground taking into account hatching capacity, aiming to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to provide a spawning ground suitability calculation method taking into account hatching capacity, which can obtain a spawning ground suitability that better meets the needs of fish spawning and hatching period, so as to improve the survival rate of fish during the spawning and hatching period, which is of great significance to maintaining regional fish habitats, protecting the survival of fish species, and protecting biodiversity.

[0006] To achieve the above invention objectives, the present invention discloses a method for calculating the suitability of a spawning ground taking into account the hatching capacity, which comprehensively considers the habitat factors of the fish spawning period and the time conditions required for the drifting hatching period, calculates the suitability of the spawning ground of the fish spawning period according to the suitable curve of water depth, flow velocity and water temperature during the fish spawning period, and calculates the suitability of the drifting hatching period by considering the water flow velocity and drifting distance required for the drifting hatching of fish eggs on the basis of satisfying the suitability of the spawning period, and comprehensively considers the two to obtain the comprehensive suitability of the spawning ground taking into account the hatching capacity, comprising the following steps:

[0007] S1: Select a fish species that lays drifting eggs from the target area, collect topographic and hydrological data of the fish species that lays drifting eggs during the spawning period and the drifting hatching period in the target area, establish a hydrodynamic model for the target area, and use the hydrodynamic model for the target area to simulate the change process of hydrodynamic indicators in the characteristic hydrological year of the region, and obtain a suitable curve of habitat factors for the fish species that lays drifting eggs during the spawning period, wherein the habitat factors include water depth, flow velocity, and water temperature;

[0008] S2: Based on the suitable curve of the habitat factors of the spawning period of the drifting egg-laying fish, a preliminary habitat model is established; the target area is divided into grids, each grid is used as a unit, and the suitability of the unit habitat factors is calculated according to the preliminary habitat model as the suitability of the spawning site during the spawning period, which are respectively:

[0009] S3: Calculate the fitness of fish drift incubators;

[0010] S4: Multiply the spawning ground suitability during the spawning period by the fish drifting incubator suitability to calculate the comprehensive suitability of the spawning ground.

[0011] Furthermore, the step S1 specifically includes:

[0012] (1.1) Select fish species that lay drifting eggs in the target area, monitor and organize data such as the spawning time, location of spawning grounds, habitat characteristics of spawning grounds, and time required for drifting hatching, and collect topographic and hydrological data of the drifting egg-laying fish species during the spawning period and drifting hatching period in the target area;

[0013] (1.2) A hydrodynamic model for the target area was established. The hydrodynamic index variation process of the regional characteristic hydrological year was simulated using the hydrodynamic model to obtain the suitable curve of habitat factors during the spawning period of drifting egg-laying fish.

[0014] Furthermore, step (1.2) specifically includes the following steps:

[0015] (1.2.1) Collect underwater topography and hydrological data of the target area, and organize and analyze characteristic hydrological annual conditions;

[0016] (1.2.2) Grid the target area to achieve full coverage of the area, use the hydrodynamic and water temperature models, take the characteristic flow processes of flood, normal and dry seasons as the inflow boundaries, and calculate the regional flow velocity, water depth and water temperature change process;

[0017] (1.2.3) Based on the grid and characteristic hydrological year conditions, a hydrodynamic model of the target area is established to simulate the change process of hydrodynamic indicators in the characteristic hydrological year of the region, and obtain the suitability curve of habitat factors during the spawning period of drifting eggs, including the suitability curves of flow velocity, water depth, and water temperature.

[0018] Furthermore, the step S3 specifically includes:

[0019] (3.1) Calculate the distance between the spawning ground and the nearest water retaining structure based on the location of the spawning ground and the river flow rate;

[0020] (3.2) Calculate the time T of fish egg drifting according to the distance between the spawning ground and the nearest water retaining structure and the water flow rate i ;

[0021] (3.3) The drifting time of fish eggs T i The time required for the hatching of drifting fish eggs is T di For comparison, if T i >T di It indicates that the drifting time of fish eggs meets the requirements of hatching, and the suitability of the fish drifting incubator is 1, otherwise the suitability of the fish drifting incubator is 0.

[0022]

[0023] Where: D i is the suitability of fish drift incubator; L i V is the distance between the unit and the downstream water retaining structure; i is the flow velocity at the unit; T di The time required for fish drifting eggs to hatch.

[0024] Furthermore, the step S4 specifically includes:

[0025] The comprehensive suitability of fish spawning grounds was calculated using the following formula:

[0026]

[0027] Where: CSF i The spawning site suitability of unit i taking into account the hatching capacity, the spawning site comprehensive

[0028] Suitability reflects whether the fish habitat in the river is suitable for spawning, and also indicates whether the fish eggs in the area can hatch safely and survive.

[0029] The present invention has the following beneficial effects:

[0030] When calculating the suitability of the spawning ground of fish that lay drifting eggs, the present invention comprehensively considers the habitat factors of the fish spawning period and the time conditions required for the drifting incubation period, and obtains the suitability of the fish drifting incubator taking into account the hatching ability of the fish. When guiding the selection of the restoration position of the fish spawning ground, it is not only beneficial to the spawning of fish, but more importantly, the fish eggs can survive and hatch during the drifting process, so as to improve the survival rate of the fish during the spawning and hatching period, which is of great significance to maintaining the regional fish habitat, protecting the survival of fish species, and protecting biodiversity. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a flow chart of a method for calculating the suitability of a spawning site taking into account hatching capacity according to the present invention;

[0032] Figure 2 is the fish habitat suitability curve;

[0033] Figure 3 This is a schematic diagram of the distribution of habitat suitability for spawning grounds during the spawning period of fish;

[0034] Figure 4 Flowchart to complete the habitat model;

[0035] Figure 5 Schematic diagram of the comprehensive suitability distribution of spawning grounds for fish taking into account hatching capacity. DETAILED DESCRIPTION

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, preferred embodiments are given below and described in detail with reference to the accompanying drawings.

[0037] The embodiment of the present invention provides a method for calculating the suitability of a spawning site taking into account the hatching capacity, specifically: Figure 1 As shown, the following steps are included:

[0038] S1: Select a fish species that lays drifting eggs from the target area, collect topographic and hydrological data of the fish species that lays drifting eggs during the spawning period and the drifting hatching period in the target area, establish a hydrodynamic model for the target area, and use the hydrodynamic model for the target area to simulate the change process of hydrodynamic indicators in the characteristic hydrological year of the region, and obtain a suitable curve of habitat factors for the fish species that lays drifting eggs during the spawning period, wherein the habitat factors include water depth, flow velocity, and water temperature; Step S1 specifically includes:

[0039] (1.1) Select fish species that lay drifting eggs in the target area, monitor and organize data such as the spawning time, location of spawning grounds, habitat characteristics of spawning grounds, and time required for drifting hatching, and collect topographic and hydrological data of the drifting egg-laying fish species during the spawning period and drifting hatching period in the target area;

[0040] (1.2) A hydrodynamic model for the target area was established. The hydrodynamic index variation process of the regional characteristic hydrological year was simulated using the hydrodynamic model to obtain the suitable curve of habitat factors during the spawning period of drifting egg-laying fish.

[0041] Wherein, step (1.2) specifically includes:

[0042] (1.2.1) Collect basic information such as underwater topography and hydrological data of the target area, and organize and analyze characteristic hydrological conditions;

[0043] (1.2.2) Grid the target area to achieve full coverage of the area, use the hydrodynamic and water temperature models, take the characteristic flow processes of flood, normal and dry seasons as the inflow boundaries, and calculate the changes in regional flow velocity, water depth, water temperature, etc.;

[0044] (1.2.3) Based on the grid and characteristic hydrological year conditions, a hydrodynamic model of the target area is established to simulate the change process of hydrodynamic indicators in the characteristic hydrological year of the region, and obtain the suitable curve of habitat factors during the spawning period of drifting eggs, including the suitability curves of flow velocity, water depth, and water temperature, such as Figure 2 shown.

[0045] S2: Based on the suitable curve of the habitat factors of the spawning period of the drifting egg-laying fish, a preliminary habitat model is established; the target area is divided into grids, each grid is used as a unit, and the suitability of the unit habitat factors is calculated according to the preliminary habitat model as the suitability of the spawning site during the spawning period, which are respectively: Step S2 specifically includes:

[0046] (2.1) A preliminary habitat model was established based on the fish spawning period habitat factor suitability curve and hydrodynamic changes.

[0047] (2.2) Based on the preliminary habitat model, the suitability of the unit habitat factors was calculated using the fish spawning period suitability curve, which are: (like Figure 2 The schematic diagram of spawning ground suitability distribution is shown in Figure 3 shown.

[0048] S3: Calculating the suitability of the fish drifting incubator. Step S3 specifically includes:

[0049] (3.1) Calculate the distance between the spawning ground and the nearest water retaining structure based on the location of the spawning ground and the river flow rate;

[0050] (3.2) Calculate the time T of fish egg drifting according to the distance between the spawning ground and the nearest water retaining structure and the water flow rate i ;

[0051] (3.3) The drifting time of fish eggs T i The time required for the hatching of drifting fish eggs is T di For comparison, if T i >T di It indicates that the drifting time of fish eggs meets the requirements of hatching, and the suitability of the fish drifting incubator is 1, otherwise the suitability of the fish drifting incubator is 0.

[0052]

[0053] Where: D i is the suitability of fish drift incubator; Li V is the distance between the unit and the downstream water retaining structure; i is the flow velocity at the unit; T di The time required for the incubation of drifting eggs of fish can be improved on the basis of the preliminary habitat model. Figure 4 shown.

[0054] S4: Based on the improved habitat model, the comprehensive suitability of the spawning grounds is calculated by comprehensively considering the habitat requirements of the spawning grounds during the spawning period and the time requirements during the drifting incubation period. Figure 5 shown.

[0055] Specifically, based on the perfect habitat model, taking the unit as the unit, the habitat requirements of the spawning ground and the time requirements of the drifting incubation period are comprehensively considered, and the suitability of the spawning ground of the fish and the suitability of the drifting incubation period are multiplied.

[0056] The comprehensive suitability of the spawning ground of the fish was calculated using the following formula:

[0057]

[0058] Where: CSF i is the comprehensive suitability of the spawning ground of unit i.

[0059] What is disclosed above is only a preferred embodiment of the present invention, and cannot be used to limit the scope of rights of the present invention. Therefore, the present invention is not limited to the above optional implementation mode. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in its shape or structure, all technical solutions that fall within the scope defined by the claims of the present invention fall within the protection scope of the present invention.

Claims

1. A method for calculating the suitability of a spawning site taking into account hatching capacity, characterized in that The following steps are involved: S1: Select a fish species that lays drifting eggs from the target area, collect topographic and hydrological data of the fish species that lays drifting eggs during the spawning period and the drifting hatching period in the target area, establish a hydrodynamic model for the target area, and use the hydrodynamic model for the target area to simulate the change process of hydrodynamic indicators in the characteristic hydrological year of the region, and obtain a suitable curve of habitat factors for the fish species that lays drifting eggs during the spawning period, wherein the habitat factors include water depth, flow velocity, and water temperature; S2: Based on the suitable curve of the habitat factors of the spawning period of the drifting egg-laying fish, a preliminary habitat model is established; the target area is divided into grids, each grid is used as a unit, and the suitability of the unit habitat factors is calculated according to the preliminary habitat model as the suitability of the spawning site during the spawning period, which are respectively: S3: Calculate the fitness of fish drift incubators; S4: Multiply the spawning ground suitability during the spawning period by the fish drifting incubator suitability to calculate the comprehensive suitability of the spawning ground.

2. The method according to claim 1, characterized in that The step S1 specifically includes: (1.1) Select fish species that lay drifting eggs in the target area, monitor and organize data such as the spawning time, location of spawning grounds, habitat characteristics of spawning grounds, and time required for drifting hatching, and collect topographic and hydrological data of the drifting egg-laying fish species during the spawning period and drifting hatching period in the target area; (1.2) A hydrodynamic model for the target area was established. The hydrodynamic index variation process of the regional characteristic hydrological year was simulated using the hydrodynamic model to obtain the suitable curve of habitat factors during the spawning period of drifting egg-laying fish.

3. The method according to claim 2, characterized in that Step (1.2) specifically includes the following steps: (1.2.1) Collect underwater topography and hydrological data of the target area, and organize and analyze characteristic hydrological annual conditions; (1.2.2) Grid the target area to achieve full coverage of the area, use the hydrodynamic and water temperature models, take the characteristic flow processes of flood, normal and dry seasons as the inflow boundaries, and calculate the regional flow velocity, water depth and water temperature change process; (1.2.3) Based on the grid and characteristic hydrological year conditions, a hydrodynamic model of the target area is established to simulate the change process of hydrodynamic indicators in the characteristic hydrological year of the region, and obtain the suitability curve of habitat factors during the spawning period of drifting eggs, including the suitability curves of flow velocity, water depth, and water temperature.

4. The method according to claim 1, characterized in that The step S3 specifically includes: (3.1) Calculate the distance between the spawning ground and the nearest water retaining structure based on the location of the spawning ground and the river flow rate; (3.2) Calculate the time T of fish egg drifting according to the distance between the spawning ground and the nearest water retaining structure and the water flow rate i ; (3.3) The drifting time of fish eggs T i The time required for the hatching of drifting fish eggs is T di For comparison, if T i >T di It indicates that the drifting time of fish eggs meets the requirements of hatching, and the suitability of the fish drifting incubator is 1, otherwise the suitability of the fish drifting incubator is 0. Where: D i is the suitability of fish drift incubator; L i V is the distance between the unit and the downstream water retaining structure; i is the flow velocity at the unit; T di The time required for fish drifting eggs to hatch.

5. The method according to claim 4, characterized in that The step S4 specifically includes: The comprehensive suitability of fish spawning grounds was calculated using the following formula: Where: CSF i The spawning ground suitability for unit i takes into account the hatching capacity. The comprehensive suitability of the spawning ground reflects whether the fish habitat in the river is suitable for spawning, and also indicates whether the fish eggs in the area can be safely hatched and survived.

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