Method for estimating population number of Yangtze River cowfish in dry season of Poyang Lake

Abstract

The invention discloses a method for estimating the population number of Yangtze River finless guinea in the dry season of Poyang Lake, relates to the technical field of aquatic organism protection, and provides a method for estimating the population number of the Yangtze River finless guinea in the dry season of Poyang Lake according to the change of the activity range of the Yangtze River finless guinea in different water levels in the dry season of Poyang Lake. The method comprises the following steps: establishing a function relationship between the number of Yangtze river cowfish heads and the water level under flowing visual inspection, and on the basis of long-term flowing inspection data, returning the population number estimation of the Yangtze river cowfish to spatial distribution difference caused by water level change of the Poyang Lake in combination with water level data; the Poyang Lake dry season Poyang Lake number estimation method eliminates a large error between the observation number of the Poyang Lake and the actual observation number caused by change of the Poyang Lake water level, avoids too complex algorithm and too long time of a section line sampling method, rapidly and accurately realizes the estimation of the number of the Poyang Lake dry season Yangtze River fairfishes, provides a basis for scientific decision making of a management department, and improves the Poyang Lake dry season Poyang Lake dry season Poyang Lake Poyang Lake dry season Poyang Lake Poyang Lake. Scientific support is provided for protection of Poyang Lake Yangtze River cowfishes.

Description

Technical Field

[0001] The invention relates to the technical field of aquatic organism protection, and in particular to a method for estimating the population quantity of Yangtze finless porpoises in Poyang Lake during the dry season. Background Art

[0002] Poyang Lake is a typical seasonal freshwater lake with high water level and low water level. It has a unique landscape of "a large area during floods and a narrow area during low water levels". During floods, the lake is boundless and its area can reach 3210km. 2 During low water periods, it is no different from a river, with the water area reduced to 100km 2 about.

[0003] The Yangtze finless porpoise (Neophocaena asiaeorientalis), commonly known as the "river pig", belongs to the order Cetacea, family Porpoise, genus Finless Porpoise. It is only distributed in the main stream of the middle and lower reaches of the Yangtze River and the large lakes connected to it. It has extremely high cultural value and its protection status is very important. The results of the 2017 Yangtze River freshwater dolphin survey showed that the population of Yangtze finless porpoises was about 1,000, and the population of Yangtze finless porpoises in Poyang Lake remained relatively stable at 457. The 2022 Yangtze River finless porpoise scientific survey data showed that the number of Yangtze finless porpoises has rebounded to about 1,249, and about 492 in Poyang Lake. It can be seen that the Yangtze finless porpoises in Poyang Lake play a vital role.

[0004] The current methods for estimating the population size of Yangtze finless porpoises in Poyang Lake are based on overly complex models and too many designed variables. Some errors are relatively small. Although the model back-validation is relatively good, the threshold is high, the practical application value is low, and the universality is poor. In different years and different regions, the model errors are large. How to quickly and accurately predict the number of Yangtze finless porpoises in Poyang Lake during the dry season and solve the problem of estimating the population size of Yangtze finless porpoises in Poyang Lake has become an urgent problem to be solved. Summary of the invention

[0005] The purpose of the present invention is to make up for the shortcomings of the prior art and provide a method for estimating the population size of Yangtze finless porpoises in Poyang Lake during the dry season. The method can estimate the population size of Yangtze finless porpoises in Poyang Lake based on the intercept sampling method in previous years and the data of the number of Yangtze finless porpoises observed in the long-term mobile survey of Poyang Lake, and combine the water level element broadcast data to return the estimation of the population size of Yangtze finless porpoises to the spatial distribution difference caused by the water level change of Poyang Lake, eliminate the situation where there is a large error between the number of porpoise observations and the actual number due to the water level change of Poyang Lake, and avoid the overly complex algorithm of the intercept sampling method, so as to provide a basis for scientific decision-making of management departments and provide scientific support for the protection of Yangtze finless porpoises in Poyang Lake.

[0006] To solve the above technical problems, the present invention provides the following technical solution: A method for estimating the population of finless porpoises in the Yangtze River during the dry season of Poyang Lake. The specific steps of the method are as follows:

[0007] S100 Collect data: Comprehensively collect the population of finless porpoises in the Yangtze River in Poyang Lake in the past few years, the average water level value of Xingzi Station in Poyang Lake that has been continuously stable for one week during the dry season of Poyang Lake, and the head count data of finless porpoises in Poyang Lake observed by mobile visual inspection at different water levels over the years;

[0008] S200 Establish a function equation: Establish a non-linear function relationship between the water level during the dry season of Poyang Lake and the head count of finless porpoises observed in Poyang Lake, obtain the function equation, and obtain the visible coefficient R of finless porpoises in the Yangtze River during the dry season of Poyang Lake at different water levels;

[0009] S300 Substitute the value into the function equation: Take the average value of the daily water level broadcast value of Xingzi Station during the one-week stable water level period of the next dry season of Poyang Lake, and substitute this average value into the function equation to obtain the visible coefficient R of finless porpoises in the Yangtze River during the dry season of Poyang Lake at this water level;

[0010] S400 Design requirements for mobile visual inspection: Utilize the window period of one-week stable water level during the dry season of Poyang Lake, conduct aerial monitoring along the designed route using a drone swarm, and synchronize manual observation by fishing boats to conduct mobile visual inspection on finless porpoises in Poyang Lake, obtain the observed head count N, and eliminate duplicate data;

[0011] S500 Calculate the population: Use the calculation formula to obtain the population S of finless porpoises in the Yangtze River during the dry season of Poyang Lake, where N represents the head count of finless porpoises observed in Poyang Lake during this mobile visual inspection, and R represents the visible coefficient of finless porpoises in the Yangtze River during the dry season of Poyang Lake during this mobile visual inspection.

[0012] Furthermore, the dry season of Poyang Lake in S100 is marked by the water level of Xingzi Station, a landmark hydrological station in Poyang Lake, dropping below 12 meters, indicating the entry of Poyang Lake into the dry season, and the inspection is carried out when the water level of Xingzi Station in Poyang Lake is stable for 1 week during the dry season.

[0013] Furthermore, the visible coefficient R of finless porpoises in the Yangtze River during the dry season of Poyang Lake in S200 = -0.0053h 2 - 0.0209h + 1.5554, where R represents the visible coefficient of finless porpoises in the Yangtze River during the dry season of Poyang Lake under visual observation at that time, and h represents the average Xingzi water level of the one-week stable water level during the dry season of Poyang Lake.

[0014] Furthermore, the completion time of the mobile visual inspection in S400 is within 3 days, and the coverage range is the waterway connecting to the Yangtze River, the main lake area of Poyang Lake, and the entrances of the "Five Rivers" into the lake.

[0015] Furthermore, the mobile visual inspection only counts the head count data of finless porpoises in Poyang Lake observed in one-way of the flight route.

[0016] Furthermore, the method for the S400 to eliminate duplicate data includes:

[0017] Integrate the N values of the drone and manual observations, and only count the first sightings of finless porpoises in the one-way route;

[0018] Exclude duplicate counts caused by the migration of finless porpoises at night;

[0019] Mark the observation points through GPS positioning to avoid duplicate records in the same area.

[0020] Furthermore, the S500 adopts a mobile investigation method, that is, using a small fishing boat to conduct visual observations along the designed investigation route at a speed of 8 - 12 km / h. The observation platform uses three observers, with 2 main observers on the left and right, and the middle one is a data recorder and also a secondary observer.

[0021] Furthermore, the water level data of the S300 needs to collect the reported values of Xingzi Station every day, and calculate the average value of 7 consecutive days as the water level input value for a stable week.

[0022] Furthermore, the one-way route covers the following areas:

[0023] The main lake area of Poyang Lake: The continuous water area from Ruihong Town, Yugan County to Duchang County, Lushan City, and Wucheng Town, Yongxiu County;

[0024] The waterway connecting to the Yangtze River: The Yangtze River connecting waterway between Hukou County and Xingzi County;

[0025] The mouths of the five rivers flowing into the lake: The water area within a radius of 5 kilometers at the mouths of the Ganjiang River, Fuhe River, Xinjiang River, Raohe River, and Xiushui River flowing into the lake.

[0026] Compared with the prior art, this method for estimating the population quantity of the Yangtze finless porpoise in the dry season of Poyang Lake has the following beneficial effects:

[0027] First, the method for estimating the population quantity of the Yangtze finless porpoise in the dry season of Poyang Lake provided by the present invention, based on long-term mobile investigation data and combined with water level data, regresses the estimation of the Yangtze finless porpoise population quantity to the spatial distribution differences caused by the water level changes in Poyang Lake, eliminates the large error between the observed number of finless porpoises and the actual situation caused by the water level changes in Poyang Lake, and at the same time avoids the overly complex algorithm and long time of the line transect sampling method, quickly and accurately realizes the estimation of the number of Yangtze finless porpoises in the dry season of Poyang Lake, provides a basis for the scientific decision-making of the management department, and provides scientific support for the protection of the Yangtze finless porpoise in Poyang Lake.

[0028] II. A method for estimating the population of finless porpoises in the Yangtze River during the dry season of Poyang Lake. In this method, the calculation of the visibility coefficient R at different water levels during the dry season of Poyang Lake is based on the number of times finless porpoises are observed at different water levels, and a non-linear function relationship between the number of times finless porpoises are observed and the water level during the dry season of Poyang Lake is established.

[0029] Other advantages, objectives, and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be learned from the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0031] Figure 1 It is an operation flowchart of a method for estimating the population of finless porpoises in the Yangtze River during the dry season of Poyang Lake;

[0032] Figure 2 It is the inspection route map of the present invention;

[0033] Figure 3 It is the satellite map of the inspection route of the present invention;

[0034] Figure 4 It is the satellite map of the inspection route of the present invention in 2018;

[0035] Figure 5 It is a schematic diagram of the position distribution of the number of finless porpoises at Xingzi water level of 11.58 meters in 2018 of the present invention;

[0036] Figure 6 It is the satellite map of the inspection route of the present invention in 2019;

[0037] Figure 7 It is a schematic diagram of the position distribution of the number of finless porpoises at Xingzi water level of 10.02 meters in 2019 of the present invention;

[0038] Figure 8 It is the satellite map of the inspection route of the present invention in 2020;

[0039] Figure 9 It is a schematic diagram of the position distribution of the number of finless porpoises at Xingzi water level of 9.01 meters in 2020 of the present invention;

[0040] Figure 10Schematic diagram of the initial positions of finless porpoises at Xingzi water level of 7.70 m in 2021 for the present invention;

[0041] Figure 11 Schematic diagram of the initial positions of finless porpoises at Xingzi water level of 7.59 m in 2022 for the present invention;

[0042] Figure 12 Schematic diagram of the initial positions of finless porpoises at Xingzi water level of 7.81 m in 2023 for the present invention;

[0043] Figure 13 Function equation graph of the divergence - convergence coefficient and Xingzi water level for the present invention. Detailed implementation manners

[0044] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following, in combination with the attached drawings and preferred embodiments, details the specific implementation manners, structures, features and their effects of the present invention as follows.

[0045] Next, embodiments are given to illustrate the present invention. However, the present invention is not limited to the following embodiments. The "population quantity of the Yangtze finless porpoise in Poyang Lake announced in 2017", "population quantity of the Yangtze finless porpoise in Poyang Lake announced in 2022" and "water level broadcast value of the Hydrological Bureau" involved in the present invention are all common knowledge and can be obtained from public channels.

[0046] Embodiment 1

[0047] This embodiment provides a specific process for estimating the population quantity of the Yangtze finless porpoise in the dry season of Poyang Lake. This implementation process fully considers the differences in the spatial distribution of the Yangtze finless porpoise in Poyang Lake at different water levels, and returns the estimation of the population quantity of the Yangtze finless porpoise to the spatial distribution differences caused by the water level changes in Poyang Lake, effectively eliminating the large error between the observed number of finless porpoises and the actual number caused by the water level changes in Poyang Lake, and improving the accuracy of the estimation.

[0048] In specific implementation, the preparatory work includes determining the investigation time, selecting the investigation water level, choosing the investigation weather, determining the investigation route, and determining the investigation method, as follows:

[0049] Investigation time: In the dry season of Poyang Lake, when the water level of Xingzi Station, the iconic hydrological station in Poyang Lake, drops below 12 m, it marks the entry of Poyang Lake into the dry season; the investigation is carried out when the water level of Xingzi Station in the dry season of Poyang Lake is stable for about 1 week, and the designed investigation time is 2.5 days of travel time;

[0050] Investigation water level: Select the time when the water level in the dry season of Poyang Lake is stable for about 1 week. At this time, the water level is relatively stable, and the distribution of the Yangtze finless porpoise in Poyang Lake tends to be stable. Choosing a short time to complete the whole - lake investigation is based on minimizing the error caused by the migration of the Yangtze finless porpoise at night and during non - investigation periods;

[0051] Investigation weather selection: Try to select a weather condition without wind and waves for the investigation;

[0052] Investigation route design: See the investigation route map in Figure 2 , and see the satellite map of the investigation route in Figure 3 , starting from Yugan County to Duchang County, Lushan City, Yongxiu County, and Hukou County; the investigation scope covers the main lake area of Poyang Lake and the estuaries of the "Five Rivers" into the lake. The specific route design is as follows: On the first day, start from the dock of Ruihong Town, Yugan County, go downstream to Tangyin and then upstream to Longkou Village, Poyang County, and then turn back and go downstream to the dock of Duchang County; on the second day, go downstream from Duchang County to Xiumen Mountain and then upstream to Wucheng Town, Yongxiu County, and then turn back and go downstream to Xingzi County; on the third day, go downstream from Xingzi County to Hukou County, and then return to Hukou County by bypassing the head of Jiangzhou Town from Hukou County;

[0053] Investigation method: Adopt the mobile investigation method, that is, use a small fishing boat to conduct visual observations along the designed investigation route at a speed of 8 - 12 km / h. The observation platform uses three observers, with 2 main observers on the left and right and the data recorder in the middle also serving as the secondary observer.

[0054] After the preparatory work is completed, collect the collected data, such as Figure 1 shown, and finally determine the specific steps of the method for estimating the population quantity of the finless porpoises in the dry season of the Yangtze River in Poyang Lake:

[0055] S100. Data collection: Comprehensively collect the water level monitoring data at the Xingzi station during the dry season of Poyang Lake and the mobile investigation data of the finless porpoises in Poyang Lake under different typical water levels, and obtain the average water level value that remains stable for a week and the number of finless porpoises observed in one - way under different water levels;

[0056] S200. Establish a function equation: Use the population quantity (heads) of the finless porpoises in Poyang Lake announced in 2017 and 2022 to obtain the ratio of the number of finless porpoises observed during the dry season of Poyang Lake to the population quantity (heads) under different water levels, establish a non - linear function relationship between the visible coefficient R of the finless porpoises in the dry season of Poyang Lake and the water level, and obtain the function equation, that is, R = - 0.0053h² - 0.0209h + 1.5554, where R represents the visible coefficient of the finless porpoises in the dry season of Poyang Lake, h represents the average Xingzi water level that remains stable for a week during the dry season of Poyang Lake, and the water level data is from the value reported by the local hydrological bureau in that year;

[0057] S300. Substitute the value into the function equation: Take the average value of the daily Xingzi station water level broadcast values that remain stable for a week during the next dry season of Poyang Lake, substitute this average value into the function equation, and obtain the visible coefficient R of the finless porpoises in Poyang Lake at this water level;

[0058] S400. Design a mobile inspection route: Utilize the one-week window period with stable water levels during the dry season of Poyang Lake. Conduct a mobile inspection of the finless porpoises in Poyang Lake along the designed route. The route is required to cover the entire Poyang Lake area, count the waterways and the mouths of the "Five Rivers" flowing into the lake. Try to make it a one-way trip to reduce errors caused by repeated observations or nocturnal migration of finless porpoises, and obtain the number of observations N for the first time. When determining the value of N, duplicate data should be excluded.

[0059] S500. Calculate the predicted population value: Use the calculation formula S = N / R to obtain the predicted population value of the finless porpoises in Poyang Lake during the dry season. Among them, S represents the predicted population value of the finless porpoises in Poyang Lake during the dry season, N represents the number of finless porpoises observed in one-way during the ecological inspection in the current year, and R represents the visibility coefficient of the finless porpoises in Poyang Lake during the dry season of the ecological inspection.

[0060] In this embodiment, according to the results of the ecological scientific inspections of finless porpoises in 2017 and 2022, there were 457 and 492 finless porpoises in Poyang Lake respectively, with an average annual growth rate of 1.53%.

[0061] Example Two

[0062] In 2018, when the water level of the Xingzi Hydrological Station, the landmark hydrological station in Poyang Lake, dropped below 12 meters, that is, when it was 11.58 meters, an inspection was conducted. For the satellite map of the inspection route in 2018, see Figure 4 , starting from the dock in Ruihong Town, Yugan County on the first day, going downstream to Tangyin, then upstream to Longkou Village, Poyang County, and then turning back and going downstream to the dock in Duchang County; on the second day, going downstream from Duchang County to Xiumen Mountain, then upstream to Wucheng Town, Yongxiu County, and then turning back and going downstream to Xingzi County; on the third day, going downstream from Xingzi County to Hukou County, and then returning from Hukou County around the head of Jiangzhou Town to Hukou County. Finally, a total of 283 finless porpoises were found. For the schematic diagram of the location distribution of the finless porpoises at the Xingzi water level of 11.58 meters in 2018, see Figure 5 .

[0063] Example Three

[0064] In 2019, when the water level of the Xingzi Hydrological Station, the landmark hydrological station in Poyang Lake, dropped below 12 meters, that is, when it was 10.02 meters, an inspection was conducted. For the satellite map of the inspection route in 2019, see Figure 6 , starting from the dock in Ruihong Town, Yugan County on the first day, going downstream to Tangyin, then upstream to Longkou Village, Poyang County, and then turning back and going downstream to the dock in Duchang County; on the second day, going downstream from Duchang County to Xiumen Mountain, then upstream to Wucheng Town, Yongxiu County, and then turning back and going downstream to Xingzi County; on the third day, going downstream from Xingzi County to Hukou County, and then returning from Hukou County around the head of Jiangzhou Town to Hukou County. Finally, a total of 370 finless porpoises were found. For the schematic diagram of the location distribution of the finless porpoises at the Xingzi water level of 10.02 meters in 2019, see Figure 7 .

[0065] Example Four

[0066] In 2020, when the water level at the Xingzi Station, the iconic hydrological station of Poyang Lake, dropped below 12 meters, i.e., 9.01 meters, an investigation was carried out. For the satellite map of the investigation route in 2020, see Figure 8 , starting from the dock in Ruihong Town, Yugan County on the first day, going downstream to Tangyin, then upstream to Longkou Village, Poyang County, and then turning back and going downstream to the dock in Duchang County; on the second day, going downstream from Duchang County to Xiumen Mountain, then upstream to Wucheng Town, Yongxiu County, and then turning back and going downstream to Xingzi County; on the third day, going downstream from Xingzi County to Hukou County, and then returning from Hukou County around the head of Jiangzhou Town to Hukou County. Finally, a total of 470 sightings of finless porpoises were found. For the schematic diagram of the location distribution of finless porpoise sightings at a water level of 9.01 meters at Xingzi in 2020, see Figure 9 .

[0067] Example 5

[0068] In 2021, when the water level at the Xingzi Station, the iconic hydrological station of Poyang Lake, dropped below 12 meters, i.e., 7.70 meters, an investigation was carried out. Starting from the dock in Ruihong Town, Yugan County on the first day, going downstream to Tangyin, then upstream to Longkou Village, Poyang County, and then turning back and going downstream to the dock in Duchang County; on the second day, going downstream from Duchang County to Xiumen Mountain, then upstream to Wucheng Town, Yongxiu County, and then turning back and going downstream to Xingzi County; on the third day, going downstream from Xingzi County to Hukou County, and then returning from Hukou County around the head of Jiangzhou Town to Hukou County. Finally, a total of 501 sightings of finless porpoises were found. For the schematic diagram of the location distribution of finless porpoise sightings at a water level of 7.7 meters at Xingzi in 2021, see Figure 10 .

[0069] Example 6

[0070] In 2022, when the water level at the Xingzi Station, the iconic hydrological station of Poyang Lake, dropped below 12 meters, i.e., 7.59 meters, an investigation was carried out. Starting from the dock in Ruihong Town, Yugan County on the first day, going downstream to Tangyin, then upstream to Longkou Village, Poyang County, and then turning back and going downstream to the dock in Duchang County; on the second day, going downstream from Duchang County to Xiumen Mountain, then upstream to Wucheng Town, Yongxiu County, and then turning back and going downstream to Xingzi County; on the third day, going downstream from Xingzi County to Hukou County, and then returning from Hukou County around the head of Jiangzhou Town to Hukou County. Finally, a total of 570 sightings of finless porpoises were found. For the schematic diagram of the location distribution of finless porpoise sightings at a water level of 7.59 meters at Xingzi in 2022, see Figure 11 .

[0071] Example 7

[0072] In 2023, when the water level at the Xingzi Station, the iconic hydrological station of Poyang Lake, dropped below 12 meters, i.e., 7.81 meters, an investigation was carried out. Starting from the dock in Ruihong Town, Yugan County on the first day, going downstream to Tangyin, then upstream to Longkou Village, Poyang County, and then turning back and going downstream to the dock in Duchang County; on the second day, going downstream from Duchang County to Xiumen Mountain, then upstream to Wucheng Town, Yongxiu County, and then turning back and going downstream to Xingzi County; on the third day, going downstream from Xingzi County to Hukou County, and then returning from Hukou County around the head of Jiangzhou Town to Hukou County. Finally, a total of 514 sightings of finless porpoises were found. For the schematic diagram of the location distribution of finless porpoise sightings at a water level of 7.81 meters at Xingzi in 2023, seeFigure 12 .

[0073] Based on the first sighting data of finless porpoises obtained from Examples II, III, IV, V, VI, and VII, calculate the corresponding ratios of the Xingzi water level in Poyang Lake to the first sighting of finless porpoises from 2018 to 2022. The corresponding ratios of the Xingzi water level in Poyang Lake to the first sighting of finless porpoises from 2018 to 2022 are shown in the following table:

[0074]

[0075]

[0076] Use the method for estimating the population size of the Yangtze finless porpoise in the dry season of Poyang Lake provided in Example 1 for calculation. In this method, the calculation of the visibility coefficient R at different water levels in the dry season of Poyang Lake is based on the first sighting of the Yangtze finless porpoise at different water levels, and a non-linear function relationship between different water levels in the dry season of Poyang Lake and the first sighting is established, that is, the visibility coefficient R = -0.0053h2 - 0.0209h + 1.5554 (r 2 = 0.9483), the population size S = the first sighting N / the dispersion coefficient R. The function equation graph of the dispersion coefficient and the Xingzi water level can be seen in Figure 13 .

[0077] In summary, the present invention establishes a function relationship between the first sighting of the Yangtze finless porpoise and the water level according to the change of the activity range of the Yangtze finless porpoise at different water levels in the dry season of Poyang Lake; first, determine the visibility coefficient R of the Yangtze finless porpoise at different water levels in the dry season of Poyang Lake. The visibility coefficient R is determined by fitting the number of the Yangtze finless porpoises observed along the same observation route at different water levels in the dry season of Poyang Lake. Then, estimate the population size of the Yangtze finless porpoise in Poyang Lake according to the water level value and the first sighting of the Yangtze finless porpoise during each investigation. The present invention fully considers the differences in the spatial distribution of the Yangtze finless porpoise at different water levels in Poyang Lake, and the number of sightings observed is the result of the combined action of the distribution of the Yangtze finless porpoise at different water levels and the visible range of the naked eye during observation in space.

[0078] The method for estimating the population size of the Yangtze finless porpoise in the dry season of Poyang Lake provided by the present invention, based on long-term field investigation data and combined with water level element forecast data of the water conservancy department, regresses the estimation of the Yangtze finless porpoise population size to the spatial distribution differences caused by the water level change in Poyang Lake, eliminates the large error between the number of finless porpoise sightings and the actual situation caused by the water level change in Poyang Lake, and at the same time avoids the overly complex algorithm and long time of the line intercept sampling method, quickly and accurately realizes the estimation of the number of the Yangtze finless porpoise in the dry season of Poyang Lake, provides a basis for scientific decision-making by management departments, and provides scientific support for the protection of the Yangtze finless porpoise in Poyang Lake.

[0079] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the above-disclosed technical content within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for estimating the population size of the finless porpoise in the Yangtze River during the dry season of Poyang Lake, characterized in that, The specific steps of this method are as follows: S100 Collect data: Comprehensively collect the population quantity of the finless porpoises in the Poyang Lake and the Yangtze River in the past few years, the average water level value of Xingzi Station in the Poyang Lake during the dry season for a continuous and stable week, and the head count data of the finless porpoises in the Poyang Lake and the Yangtze River observed through visual inspection at different water levels over the years; S200 Establish a function equation: Establish a non-linear function relationship between the water level during the dry season of the Poyang Lake and the head count of the finless porpoises observed in the Poyang Lake, obtain the function equation, and obtain the visible coefficient R of the finless porpoises in the Poyang Lake during the dry season at different water levels; S300 Substitute numerical values into the function equation: Take the average value of the water level broadcast values of Xingzi Station every day when the water level in the Poyang Lake during the next dry season is stable for a week, substitute this average value into the function equation, and obtain the visible coefficient R of the finless porpoises in the Poyang Lake during the dry season at this water level; S400 Design requirements for mobile visual inspection: Utilize the window period when the water level in the Poyang Lake is stable for a week during the dry season, conduct aerial photography monitoring along the designed route using a drone swarm, and synchronize the manual observation by fishing boats to conduct mobile visual inspection on the finless porpoises in the Poyang Lake and the Yangtze River, obtain the observed head count N, and eliminate duplicate data; S500 Calculate the population size: Using the calculation formula to obtain the population size S of the finless porpoises in Poyang Lake during the dry season. Here, N represents the number of finless porpoises observed in Poyang Lake during this mobile visual inspection, and R represents the visibility coefficient of finless porpoises in Poyang Lake during the dry season in this mobile visual inspection.

2. The method for estimating the population size of the Yangtze finless porpoise during the dry season of Poyang Lake according to claim 1, wherein In S100, the dry season of the Poyang Lake is marked by the water level of Xingzi Station, a landmark hydrological station in the Poyang Lake, dropping below 12 meters, indicating the entry of the Poyang Lake into the dry season. The inspection is carried out when the water level of Xingzi Station in the Poyang Lake is stable for 1 week.

3. The method for estimating the population size of the finless porpoise in the Yangtze River during the dry season of Poyang Lake according to claim 1, wherein The visible coefficient R of the Yangtze finless porpoise during the dry season of Poyang Lake in S200 is R = -0.0053h 2 - 0.0209h + 1.5554, where R represents the visible coefficient of the Yangtze finless porpoise during the dry season of Poyang Lake under visual observation at that time, and h represents the average Xingzi water level when the water level of Poyang Lake remains stable for one week during the dry season.

4. The method for estimating the population size of the Yangtze finless porpoise during the dry season of Poyang Lake according to claim 1, characterized in that, The completion time of the mobile visual inspection in S400 is within 3 days, and the coverage range is the waterway connecting to the Yangtze River, the main lake area of the Poyang Lake, and the entrances of the "Five Rivers" into the lake.

5. The method for estimating the population size of the finless porpoise in the Yangtze River during the dry season of Poyang Lake according to claim 4, wherein The mobile visual inspection only counts the head count data of the finless porpoises in the Poyang Lake and the Yangtze River observed in one-way of the flight route.

6. The method for estimating the population size of the finless porpoise in the Yangtze River during the dry season of Poyang Lake according to claim 1, characterized in that, The method for eliminating duplicate data in S400 includes: Integrate the N values observed by drones and manually, and only count the head count of the finless porpoises observed for the first time in the one-way flight route; Exclude duplicate counting caused by the migration of finless porpoises at night; Mark the observation points through GPS positioning to avoid duplicate recording in the same area.

7. The method for estimating the population size of the finless porpoise in the Yangtze River during the dry season of Poyang Lake according to claim 1, characterized in that, In S500, the mobile inspection method is adopted, that is, a small fishing boat is used to conduct visual observation along the inspection-designed route at a speed of 8 - 12 km / h. The observation platform uses three observers, with 2 main observers on the left and right, and the data recorder in the middle also serves as the secondary observer.

8. The method for estimating the population size of the finless porpoise in the Yangtze River during the dry season of Poyang Lake according to claim 1, wherein In S300, the water level data needs to collect the broadcast values of Xingzi Station every day, and calculate the average value of 7 consecutive days as the water level input value for a stable week.

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