Method and device for identifying large yellow croaker populations based on otolith carbon and oxygen stable isotopes

Abstract

The method and device for identifying large yellow croaker populations based on otolith carbon and oxygen stable isotopes provided in the present application belong to the field of fish population identification. The method provided in the present application determines the first target isotope through variance calculation and contribution analysis, and then identifies whether the large yellow croaker is farmed or wild. This method is more objective and accurate. Compared with traditional morphological or simple labeling methods, the differences in otolith carbon and oxygen stable isotopes affected by the environment and food sources can be used to more accurately divide populations and avoid misjudgments caused by factors such as small individual morphological differences or loss of labels. In a complex fishery market environment, it can effectively distinguish between farmed and wild large yellow croaker, which helps to regulate market order and protect wild fishery resources.

Description

Technical Field

[0001] The present application relates to the technical field of fish population identification, and in particular to a method and device for identifying large yellow croaker populations based on otolith carbon and oxygen stable isotopes. Background Art

[0002] In the field of fishery resource management and ecological research, accurate identification of the source of large yellow croaker populations (such as farmed and wild) and more detailed population characteristics (such as the release nature of farmed populations and the offshore or offshore nature of wild populations) are crucial for scientific management of fishery resources and in-depth understanding of marine ecosystems. As an important fishery resource, the changes in the quantity of large yellow croaker and the changes in its population structure have attracted widespread attention. At present, the complexity of fishery activities and the variability of the marine ecological environment make it difficult for traditional population identification methods to meet the needs of precise research and management.

[0003] Currently, there are two main methods for identifying large yellow croaker populations: morphological identification methods and molecular biological identification methods. The morphological identification method is to distinguish different populations by observing and measuring the external morphological characteristics (such as body length, body height, scale characteristics, fin morphology, etc.) and internal anatomical structure (such as otolith morphology, number of vertebrae, etc.) of large yellow croaker; the molecular biological identification method is to use molecular marker technology, such as DNA sequencing, microsatellite markers, etc., to analyze the genetic sequence differences of large yellow croaker to identify populations.

[0004] However, the morphological identification method relies on the experience and subjective judgment of researchers, which is highly subjective and affects the accuracy and reliability of the results; the molecular biology identification method requires professional laboratory equipment and technicians, which is costly and complex to operate. Summary of the invention

[0005] In view of this, the present application provides a method and device for identifying large yellow croaker populations based on otolith carbon and oxygen stable isotopes, which can accurately and reliably understand the changes in the migration of large yellow croaker populations through simple operations.

[0006] Specifically, the present application is implemented through the following technical solutions:

[0007] The first aspect of the present application provides a method for identifying a large yellow croaker population based on otolith carbon and oxygen stable isotopes, the method comprising:

[0008] The variances of carbon stable isotopes and oxygen stable isotopes in the large yellow croaker samples are calculated respectively, and the contribution of the carbon stable isotopes and oxygen stable isotopes to the identification results are identified based on the variance results;

[0009] Determine a first target isotope based on the contribution, and identify the source type of the large yellow croaker population to be identified according to the first target isotope, wherein the source type includes farmed and wild;

[0010] For the first sub-population whose source type is the aquaculture type, determining the second target isotope according to the contribution and the first identification type of the first sub-population, clustering the first sub-population according to the second target isotope and the first time-related parameter, and obtaining a first identification result corresponding to the first identification type of the first sub-population, where the first identification type is whether to release;

[0011] For the second subpopulation whose source type is the wild type, determining a third target isotope according to the contribution degree and the second identification type of the second subpopulation, clustering the second subpopulation according to the third target isotope and a second time-related parameter, and obtaining a second identification result corresponding to the second identification type of the second subpopulation, where the second identification type is whether it is near the sea;

[0012] The identification result of the large yellow croaker population to be identified is obtained by combining the breeding type, the first identification result and the second identification result.

[0013] A second aspect of the present application provides a device for identifying large yellow croaker populations based on otolith carbon and oxygen stable isotopes, the device comprising an identification module, a processing module and an acquisition module;

[0014] The identification module is used to calculate the variance of the carbon stable isotope and the oxygen stable isotope in the large yellow croaker sample, and identify the contribution of the carbon stable isotope and the oxygen stable isotope to the identification result based on the variance result;

[0015] The identification module is further used to determine a first target isotope based on the contribution, and identify the source type of the large yellow croaker population to be identified according to the first target isotope, wherein the source type includes farmed and wild;

[0016] The processing module is used to determine the second target isotope for the first sub-population whose source type is the aquaculture type according to the contribution and the first identification type of the first sub-population, cluster the first sub-population according to the second target isotope and the first time-related parameter, and obtain a first identification result corresponding to the first identification type of the first sub-population, where the first identification type is whether to release;

[0017] The processing module is further used to determine, for the second subpopulation whose source type is the wild type, a third target isotope according to the contribution and the second identification type of the second subpopulation, cluster the second subpopulation according to the third target isotope and a second time-related parameter, and obtain a second identification result corresponding to the second identification type of the second subpopulation, where the second identification type is whether it is near the sea;

[0018] The acquisition module is used to obtain the identification result of the large yellow croaker group to be identified by combining the breeding type, the first identification result and the second identification result.

[0019] The present application provides a method and device for identifying large yellow croaker populations based on otolith carbon and oxygen stable isotopes. Considering that carbon stable isotopes and oxygen stable isotopes are sensitive to different aspects of large yellow croaker, they can contribute to the identification results of large yellow croaker populations. Considering that different types of wild or cultivated, near sea or offshore, lifelong cultivated or exiled are ultimately to be identified, the method provided by the present invention uses two isotopes for identification at the same time. Compared with the traditional fusion method of identification results, the present invention determines their contribution to the identification results by calculating the variance of carbon and oxygen stable isotopes, and then determines the isotope with the largest contribution to the identification results based on the contribution to obtain the large yellow croaker population identification results. This method can effectively utilize the information carried by stable isotopes in otoliths, maximize the use of different isotopes to the sensitive characteristics of large yellow croaker population characteristics, and overcome the problems of large interference from environmental factors, strong subjectivity, and difficulty in distinguishing subtle differences in traditional morphological identification methods. Between some similar-shaped cultivated and wild large yellow croakers, stable isotope characteristics can provide a more objective and accurate basis for distinction, which helps fishery resource management departments to accurately grasp the source of large yellow croakers on the market. For the first sub-group of farmed type, further classification is carried out according to whether it is released, and the first identification result is obtained by determining the second target isotope and the first time-related parameter clustering, which can clearly distinguish the farmed large yellow croaker that is released and not released, which is of great significance for evaluating the effect of reproduction and release; for the second sub-group of wild type, classification is carried out according to whether it is near the coast, and the second identification result is obtained by clustering the third target isotope and the second time-related parameter, which helps to deeply understand the ecological distribution of wild large yellow croaker, avoid the use of complex model training and image recognition algorithms, reduce the complexity of large yellow croaker identification, but improve the accuracy of large yellow croaker identification. It is of great value for studying the ecological habits, migration patterns and the influence of different marine environments on the growth and development of wild large yellow croaker. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A flow chart of Example 1 of the method for identifying large yellow croaker populations based on otolith carbon and oxygen stable isotopes provided in this application;

[0021] Figure 2 A schematic diagram of the otolith shown in this application;

[0022] Figure 3 A schematic diagram of variance analysis results exemplarily shown in this application;

[0023] Figure 4 This is a schematic diagram of the clustering results of the values ​​of the first target isotope exemplified in this application;

[0024] Figure 5 This is a schematic diagram of the clustering result of the first subgroup exemplarily shown in this application;

[0025] Figure 6 This is a schematic diagram of the clustering result of the second subgroup exemplified in this application;

[0026] Figure 7 The sample mean change graph of carbon-stable elements and oxygen-stable elements in otolith samples of different groups of large yellow croaker from the core to the second winter age shown in this application;

[0027] Figure 8 A schematic diagram of a determined life path exemplified for this application;

[0028] Fig. 9 This is a schematic diagram of the structure of the first embodiment of the device for identifying large yellow croaker populations based on otolith carbon and oxygen stable isotopes provided in the present application. DETAILED DESCRIPTION

[0029] Here, exemplary embodiments are described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application.

[0030] The terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used in this article refers to and includes any or all possible combinations of one or more associated listed items.

[0031] It should be understood that although the terms first, second, third, etc. may be used in the present application to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0032] Specific embodiments are given below to introduce the technical solution of the present application in detail.

[0033] Figure 1 This is a flow chart of Example 1 of the method for identifying large yellow croaker populations based on otolith carbon and oxygen stable isotopes provided in this application. Please refer to Figure 1 , the method provided in this embodiment may include:

[0034] S101. Calculate the variance of carbon stable isotopes and oxygen stable isotopes in large yellow croaker samples respectively, and identify the contribution of the carbon stable isotopes and oxygen stable isotopes to the identification results based on the variance results.

[0035] It should be noted that in this application, the changes in the migration of large yellow croaker populations were studied by measuring the content of carbon stable isotopes and oxygen stable isotopes in large yellow croaker otoliths. The specific carbon stable isotopes selected were δ13C (carbon-13 isotope ratio, specifically the ratio of carbon-13 to carbon-12) and δ18O (oxygen-18 isotope ratio, specifically the ratio of oxygen-18 to oxygen-16). This is because different food sources have different δ13C characteristics. In an ecosystem, plants absorb carbon dioxide to synthesize organic matter through photosynthesis. C3 plants (such as most temperate plants) and C4 plants (such as some tropical herbs) have different absorption and fractionation effects on carbon-12 and carbon-13 during photosynthesis, resulting in significant differences in their δ13C value ranges. Large yellow croaker feeds on phytoplankton or other organisms, and the δ13C characteristics of its food source will be transmitted and recorded in the otoliths. For example, in aquaculture, the composition of the feed of yellow croaker is relatively fixed, and its δ13C value may be different from the food source in the natural environment. If the feed contains more C4 plant components, the δ13C value of the otolith of farmed yellow croaker may be relatively low; while wild yellow croaker feeds on a variety of organisms in the natural environment, the δ13C value of its otolith will be affected by the δ13C values ​​of different organisms in the food web, which makes δ13C an effective indicator for tracking the food source and ecological niche of yellow croaker.

[0036] When the food source of yellow croaker changes, such as migrating from one area to another, or being released from an artificial breeding environment to a natural environment, the change in its food composition will lead to a corresponding change in the δ13C value in the otolith. For example, after the release of the yellow croaker, the yellow croaker that has been released for reproduction begins to gradually eat plankton, small fish and shrimp in the natural sea area, which may cause the δ13C value to gradually increase and approach the isotopic characteristics of wild yellow croaker. This change can be used to track the life history and environmental change process of yellow croaker.

[0037] The δ18O value in seawater is closely related to water temperature and salinity. The lower the water temperature, the more 18O is relatively enriched in seawater, and the higher the δ18O value; when the salinity increases, the δ18O value of seawater will also increase. During the growth process, the otoliths of large yellow croaker are in isotopic equilibrium with the surrounding seawater, and the δ18O value in their otoliths will record the changes in temperature and salinity of their living environment. For example, the open sea environment usually has lower water temperature and higher salinity, and the otoliths of large yellow croaker living in the open sea may have higher δ18O values; while the water temperature in the nearshore environment is relatively high and the salinity is low, and the δ18O value of the otoliths of large yellow croaker living in the nearshore area may be lower. This close connection with the environment allows δ18O to well reflect the living environment characteristics of large yellow croaker.

[0038] The migration behavior of large yellow croaker will also leave traces on the δ18O value of otoliths. When large yellow croaker migrates from one environment to another, such as from a low-salinity estuary area to a high-salinity offshore area, the δ18O value of the otolith will change accordingly. By analyzing the changes in the δ18O values ​​of different parts of the otoliths (such as the core, winter age point, and edge), the migration path of large yellow croaker can be inferred, and whether it migrates between different temperature and salinity environments can be determined, thereby understanding its life history and ecological habits.

[0039] Once formed in the otoliths of large yellow croaker, carbon and oxygen stable isotopes (δ13C and δ18O) are relatively stable. Compared with other biomarkers, they are not easily disturbed by short-term physiological changes or chemical processes in the organism. It should also be noted that otoliths are a calcium carbonate mineral with a relatively stable structure that can preserve carbon and oxygen isotope information for a long time. For example, during the growth of large yellow croaker, even if other tissue components in its body may change due to metabolism, disease and other factors, the stable isotope composition in the otoliths can still reflect the environmental and food information accumulated during its growth, providing a reliable record for long-term ecological research and population tracing.

[0040] In addition, since the distribution of carbon and oxygen isotopes on a global scale has certain regularities and varies between different ecosystems and geographical regions, δ13C and δ18O are traceable. For example, the δ18O values ​​of seawater in different sea areas have their own specific ranges. By comparing the δ18O values ​​in the otoliths of large yellow croaker with the characteristic values ​​of known sea areas, its possible living area can be inferred. Similarly, the range of δ13C values ​​of different food sources can also help trace the position and source of large yellow croaker in the food web.

[0041] In the specific implementation, the variances of the carbon stable isotopes and oxygen stable isotopes in the large yellow croaker sample are calculated respectively, and the contribution of the carbon stable isotopes and oxygen stable isotopes to the identification results are identified based on the variance results, including:

[0042] (1) The otoliths of each of the large yellow croaker samples are processed to obtain samples for stable isotope analysis.

[0043] It should be noted that the processing process can be to remove the otoliths from the otic capsule of the head of the large yellow croaker sample, number the otoliths, uniformly clean them with ethanol and put them in an oven to dry. After embedding and fixing the otoliths with epoxy resin glue, put them in an oven at 38°C overnight to solidify. After demolding, write the otolith number just above the otolith and cut a thin slice of about 2mm containing the otolith core along the cross section with a cutter and stick it to a glass slide. Find the approximate outline under a microscope, polish it with 500 mesh, 2000 mesh and 4000 mesh sandpaper in turn, and compare to find the core and annual rings, and repeat until the core point is about to be exposed. Use a grinding and polishing machine equipped with a woven cloth polishing disc and polish with polishing liquid until the core is completely exposed and there are no obvious scratches on the surface. The treated otolith slices are ultrasonically cleaned in MQ (pure water system) water for 5 minutes, and then dried at 38°C overnight.

[0044] (2) Use a stable isotope analyzer to determine the values ​​of carbon stable isotopes and oxygen stable isotopes at different positions in the sample otolith.

[0045] It should be noted that a micro-sampler and a stable isotope mass spectrometer can be used for determination. The sampling diameter can be 500 μm, and the sampling positions are the otolith core, the winter age point and the edge of the otolith. Figure 2 For a schematic diagram of otoliths shown in this application, please refer to Figure 2 , the otolith core, first winter instar, second winter instar and otolith edge can be clearly observed.

[0046] (3) Based on the above values, calculate the mean of the carbon stable isotopes and oxygen stable isotopes at the same position for all samples.

[0047] It should be noted that the mean reflects the average level of carbon stable isotopes or oxygen stable isotopes in all samples at a certain position. In group analysis, different groups (such as farmed and wild yellow croaker groups) may have different means at the same position. For example, if the mean of carbon stable isotopes in the core position of the otolith of the farmed yellow croaker group is significantly lower than that of the wild yellow croaker group. For more details about the mean, please refer to the introduction of related technologies.

[0048] (4) Calculate the variance of the carbon stable isotopes and oxygen stable isotopes in the large yellow croaker sample based on the mean, and identify the contribution of the carbon stable isotopes and oxygen stable isotopes to the identification results based on the variance analysis results.

[0049] Specifically, identifying the contribution of the carbon stable isotope and the oxygen stable isotope to the identification result based on the variance analysis result includes: determining the difference in the proportion of the carbon stable isotope and the oxygen stable isotope under different first identification types and different second identification types according to the variance analysis result; based on the difference in the proportion and the environmental factors corresponding to the carbon stable isotope and the oxygen stable isotope, respectively, identifying the contribution of the carbon stable isotope and the oxygen stable isotope to the identification result; Figure 3 For an exemplary diagram of the variance analysis results shown in this application, please refer to Figure 3 From Figure a and Figure b, we can see that carbon stable isotopes contribute greatly to identifying whether the large yellow croaker population is farmed or wild.

[0050] Specifically, from the samples of known types, the carbon stable isotope (δ13C) values ​​of wild large yellow croaker otoliths have a high range of variation, a low mean difference, and a relatively large difference, but the carbon stable isotope values ​​of farmed types are less different. Therefore, once the carbon stable isotope values ​​in the population to be identified have a wide range of variation and a large mean difference, it indicates that it is a wild type, otherwise it is a farmed type.

[0051] Combined with the previous description, similarly, for samples of known types, when it is necessary to distinguish whether they are from the nearshore or offshore, the variance of δ18O accounts for a large proportion of the total variance. At this time, δ18O contributes a lot in identifying whether the large yellow croaker is from the nearshore or offshore population. Specifically, the range of variation of the oxygen stable isotope (δ18O) value of the otolith of the offshore large yellow croaker is high, the mean difference is low, and the difference value is relatively large, but the oxygen stable isotope value of the offshore type is relatively small. Therefore, once the oxygen stable isotope value in the population to be identified has a wide range of variation and a large mean difference, it means that it is a nearshore type, otherwise it is a offshore type. This is because the offshore environment is relatively complex and changeable, and is affected by multiple factors such as land runoff and shallow sea ecosystems, resulting in large fluctuations in the δ18O value of the large yellow croaker otolith. However, the oxygen stable isotope value of the offshore type is relatively small, and the offshore environment is relatively stable and uniform, making the δ18O value in the otolith of the large yellow croaker relatively stable.

[0052] S102. Determine a first target isotope based on the contribution, and identify the source type of the large yellow croaker population to be identified according to the first target isotope, wherein the source type includes farmed and wild.

[0053] It should be noted that determining the first target isotope based on the contribution, and identifying the source type of the large yellow croaker population to be identified according to the first target isotope, includes:

[0054] (1) According to the relative size of the contribution, determining that the first target isotope is a carbon stable isotope.

[0055] It should be noted that according to the results of variance analysis, the proportions of carbon stable isotopes and oxygen stable isotopes in the contribution are different, which affects the differentiation of the source of the current large yellow croaker population. Among them, carbon stable isotopes mainly affect the differentiation between farmed and wild, and oxygen stable isotopes mainly affect the relationship between nearshore and offshore, that is, carbon stable isotopes contribute more to the identification results of farmed or wild, and oxygen stable isotopes contribute more to the identification results of nearshore or offshore. When the first target isotope, it means that the main distinction is whether the source type of the large yellow croaker population is farmed or wild.

[0056] (2) Selecting the value of the first target isotope in the first region for clustering.

[0057] It should be noted that the first area is the otolith core area, which is formed in the early growth stage of large yellow croaker and is the central part of the initial formation of the otolith. Information such as the environment and food source during this period will be recorded in the isotopic composition of the otolith core. For fish, the early living environment has a profound impact on their subsequent growth, development and physiological characteristics. For example, in the juvenile stage, the food source consumed by large yellow croaker is relatively single, which is mainly determined by the specific environment in which it is located (such as plankton near the hatchery). The first target isotope value of the otolith core area can reflect the characteristics of this early food source. By clustering these values, large yellow croaker samples with similar early food sources and growth environments can be grouped together.

[0058] (3) Based on the mean difference of the first target isotope in the clustering results, the source type of the large yellow croaker population to be identified was determined.

[0059] The isotopic characteristics of the otolith core region are a key starting point for distinguishing whether large yellow croaker is farmed or wild. Farmed large yellow croaker and wild large yellow croaker are often in different environments during their early growth stages. Farmed large yellow croaker usually grows in an artificially controlled environment, and its early food supply (such as specially formulated feed) and water quality conditions are relatively stable, which makes the first target isotope values ​​in their otolith core region show different characteristics from those of wild large yellow croaker. Figure 4 This is a schematic diagram of the clustering results of the first target isotope values ​​exemplified in this application. Please refer to Figure 4 ,The first target isotope in the red category is significantly different from the first target isotope in the blue category, and the farmed and wild ones can be distinguished based on the clustering results.

[0060] S103. For the first sub-population whose source type is the aquaculture type, determine the second target isotope according to the contribution and the first identification type of the first sub-population, cluster the first sub-population according to the second target isotope and the first time-related parameter, and obtain a first identification result corresponding to the first identification type of the first sub-population, where the first identification type is whether to release.

[0061] It should be noted that determining the second target isotope based on the contribution and the first identification type of the first subgroup includes: identifying the first identification type; and determining the second target isotope based on the difference in contribution ratios of the carbon stable isotope and the oxygen stable isotope in the identified first identification type.

[0062] The contribution of carbon stable isotopes and oxygen stable isotopes to the identification results was determined by the previous variance analysis method. This contribution reflects the relative importance of the two isotopes in distinguishing the characteristics of different groups. After the first identification type (i.e., whether to release) is identified, the second target isotope needs to be determined based on the difference in the contribution ratio of carbon stable isotopes and oxygen stable isotopes in this process. If, when judging whether to release, it is found that the change of carbon stable isotopes (for example, the change from the typical carbon isotope value in the aquaculture environment to the carbon isotope value in the wild environment) plays a key role in judging the nature of the release, that is, the carbon stable isotope contributes a lot to the identification result of whether to release, then the carbon stable isotope can be determined as the second target isotope. This is because after the release, the food source of the large yellow croaker may change, causing the carbon stable isotopes in the otoliths to better reflect the transition from aquaculture to the natural environment.

[0063] Furthermore, after determining the second target isotope, the first subpopulation is clustered according to the second target isotope and the first time-related parameter to obtain a first identification result corresponding to the first identification type of the first subpopulation, including: obtaining the first time-related parameter and the second target isotope of each individual in the first subpopulation; clustering is performed based on a feature selection clustering method of the first time-related parameter and the second target isotope; based on the clustering results and known fishing information, analyzing the differences in the clustering results, and obtaining the first identification result based on the differences.

[0064] It should be noted that the first time-related parameters here are the slope from the otolith core to the first winter age and the first winter age value. These parameters can reflect the changes in large yellow croaker during a specific growth stage. For example, the slope from the otolith core to the first winter age can reflect the rate of change of the isotopic characteristics in the otoliths of large yellow croaker from the early juvenile stage to the first winter age. This rate of change may be closely related to factors such as changes in the growth environment (such as release from aquaculture to the natural environment) and changes in food sources. The first winter age value is an isotopic measurement value at a key time node, which also contains important growth information.

[0065] According to the second target isotope determined in the previous step, the value of the isotope corresponding to each individual in the first subpopulation is obtained. These values ​​are measured for each large yellow croaker individual and represent their isotopic characteristics at specific locations. Since there are both first-time related parameters and second-target isotope data, the data has a certain complexity and multidimensionality, and factors such as the distribution of these data, the amount of data, and whether there is an obvious grouping trend need to be considered. According to these characteristics of the data, the most suitable clustering method is selected for clustering. After clustering is completed, the clustering results are observed. Analyze the characteristics of the second target isotope values ​​and first-time related parameters of individuals within each cluster. For example, individuals in a cluster may have similar second target isotope values ​​and similar slopes from the otolith core to the first winter age and first winter age values, indicating that these individuals have similar change patterns during growth.

[0066] The clustering results are compared and analyzed with the known fishing information. Fishing information may include fishing location, fishing time, whether fishing is near the release area, etc. If most of the individuals in a cluster are caught near the release area, and their second target isotope values ​​and first time-related parameters show the expected change pattern after release (such as the second target isotope value is close to the characteristics of wild large yellow croaker, and the slope of the otolith core to the first winter age has a significant change), then it can be inferred that the individuals in this cluster are released. By comprehensively analyzing the differences between the clustering results and the fishing information, the first identification result of each individual in the first subgroup is determined, that is, whether they are released large yellow croaker. For example, if the clustering results are highly consistent with the fishing information and can clearly distinguish between released and non-released individuals, an accurate first identification result can be obtained. Figure 5 This is a schematic diagram of the first subgroup clustering result shown in this application. Please refer to Figure 5 By comparing the red category and the blue category, as well as the known fishing information, we can conclude that the red category with a higher slope is the reproduction and release population, and the blue category with a lower slope is the lifelong farming population.

[0067] S104. For the second subpopulation whose source type is the wild type, determine the third target isotope according to the contribution degree and the second identification type of the second subpopulation, cluster the second subpopulation according to the third target isotope and a second time-related parameter, and obtain a second identification result corresponding to the second identification type of the second subpopulation, where the second identification type is whether it is near the sea.

[0068] It should be noted that the method for determining the third target isotope can refer to the description of determining the second target isotope above. The third target isotope is different from the second target isotope. Specifically, the third target isotope is an oxygen stable isotope, that is, the oxygen stable isotope has a high contribution to the identification results of the near sea or the offshore.

[0069] Specifically, clustering the second subpopulation according to the third target isotope and the second time-related parameter to obtain a second identification result corresponding to the second identification type of the second subpopulation includes: obtaining the second time-related parameter and the third target isotope of each individual in the second subpopulation; clustering based on the feature selection clustering method of the second time-related parameter and the third target isotope; and obtaining the second identification result based on the change relationship between the second time-related parameters in the clustering result and the variance difference of the third target isotope.

[0070] It should be noted that the second time-related parameters include the slope from the otolith core to the first winter age and the slope from the first winter age to the second winter age. These parameters can reflect the changes in wild large yellow croaker at different growth stages. For example, the slope from the otolith core to the first winter age reflects the growth trend from the early stage of juvenile fish to the first winter age, while the slope from the first winter age to the second winter age reflects the changes in subsequent growth stages. These slopes may be different for wild large yellow croaker in different nearshore or offshore environments, because environmental factors (such as water temperature, food resources, etc.) can affect their growth rate and the isotope fractionation process in the otoliths.

[0071] Among them, the third target isotope value of each individual in the second subpopulation is obtained in order to distinguish the wild large yellow croaker populations in different environments. The third target isotope value of each individual reflects the isotope characteristics of the wild large yellow croaker individuals at specific positions in the otolith, which are affected by factors such as food source and environmental conditions.

[0072] Considering the properties of the second time-related parameters and the third target isotope data at the same time, and selecting an appropriate clustering method based on the characteristics of the data, it is possible to better discover natural clusters in the data without being restricted by the preset number of clusters and the shape of the data. After the clustering is completed, the changing relationship between the second time-related parameters of the individuals in each cluster is observed. For example, in a cluster, if the slopes from the otolith core to the first winter age and the slopes from the first winter age to the second winter age of most individuals show a stable proportional relationship, this may indicate that these individuals grow under similar environmental conditions and have similar growth patterns. The changing relationships of these slopes may be different between different clusters, which helps to distinguish wild large yellow croaker populations in different environments. Figure 6 This is a schematic diagram of the clustering result of the second subgroup shown in this application. Please refer to Figure 6 By comparing the constant color category and the blue category, as well as the known fishing information, it can be considered that the red category is a nearshore wild population and the blue category is an offshore wild population. At the same time, the variance of the third target isotope in each cluster is analyzed. Variance can reflect the degree of discreteness of the data. If the variance of the third target isotope in a cluster is small, it means that the individuals in the cluster are more similar in this isotope characteristic, which may mean that they come from a relatively stable and similar environment. The difference in the variance of the third target isotope between different clusters can be used as a basis for distinguishing different wild large yellow croaker populations. For example, the variance of the third target isotope of wild large yellow croaker in the nearshore may be relatively small due to relatively small environmental changes; while the variance of wild large yellow croaker in the offshore may be relatively large due to more complex environmental factors.

[0073] The second identification result of each individual in the second subpopulation is determined by comprehensively considering the change relationship of the second time-related parameter in the clustering result and the variance difference of the third target isotope. That is, it is determined whether the wild large yellow croaker belongs to the offshore population or the offshore population. For example, in a possible implementation, the change of the slope (s1) from the otolith core to the first winter age and the slope value (s2) from the first winter age to the second winter age, if the slope changes from negative to positive (s1*s2<0), and Δk=s1-s2>1, it is judged as an offshore population. If there is no positive or negative change in the slope (s1*s2>0), or there is a change from negative to positive in the slope (s1*s2<0, and Δk=s1-s2<0.5), it is judged as a offshore population.

[0074] S105. Acquire the identification result of the large yellow croaker population to be identified by combining the breeding type, the first identification result and the second identification result.

[0075] Specifically, the identification results of the large yellow croaker population to be identified can be obtained by combining the aquaculture type, the first identification result and the second identification result, including the value-added release population, the lifelong aquaculture population, the offshore wild population and the offshore wild population. Furthermore, the sample average values ​​of oxygen-stable elements and carbon-stable elements of otolith samples of different large yellow croaker populations from the core to the second winter age can be obtained according to the identification results. Figure 7 Please refer to the sample mean change chart of carbon-stable elements and oxygen-stable elements in otolith samples of different groups of yellow croaker from the core to the second winter age shown in this application. Figure 7 , Figure 7 Figure a shows the sample mean changes of carbon-stable elements in otolith samples from different groups of large yellow croaker from the core to the second winter age. Figure 7 Figure b shows the sample mean changes of oxygen-stable elements in otolith samples from different groups of large yellow croaker from the core to the second winter age. Figure 7 We can better understand the mean changes in carbon and oxygen stable elements in different groups, and then achieve group differentiation and ecological characteristic response.

[0076] It should also be noted that after obtaining the identification result of the large yellow croaker group to be identified by combining the breeding type, the first identification result and the second identification result, the following steps are included:

[0077] (1) Determine the nearshore population and offshore population based on the identification results.

[0078] Based on the previous comprehensive identification results of large yellow croaker populations, the wild large yellow croaker population is further subdivided into offshore populations and offshore populations. Specifically, this division is based on the judgment of the second identification results.

[0079] (2) Analyze the changing trends of stable isotopes in the nearshore and offshore populations to identify spawning grounds.

[0080] It should be noted that for the nearshore and offshore populations, the changing trends of their carbon and oxygen stable isotopes at different growth stages (such as from juveniles to sexual maturity) were studied separately. During the breeding season, the physiological state and behavior of large yellow croaker will change, and their food intake pattern and living environment may have specific changes, which will be reflected in the stable isotope composition of the otolith. For example, female large yellow croaker may gather in specific food-rich areas before spawning, resulting in changes in food sources, thereby changing the carbon stable isotope values ​​in the otoliths; at the same time, environmental factors such as water temperature and salinity in the breeding grounds may also affect the fractionation process of oxygen stable isotopes in the otoliths.

[0081] By analyzing the stable isotope data of a large number of samples, we can find common change patterns that occur before and after the breeding season. For example, we may find that when the offshore population approaches the breeding season, the carbon stable isotope values ​​gradually approach a certain range, and the oxygen stable isotope values ​​also have corresponding changes. These change trends can be used as clues to identify spawning grounds. If the large yellow croaker samples caught in a certain sea area generally show this specific stable isotope change pattern, and the ecological environment of the sea area (such as seabed topography, water flow, etc.) is also suitable for large yellow croaker spawning, then it can be inferred that the sea area may be a spawning ground.

[0082] (3) Correcting the spawning grounds based on environmental data of the coastal and offshore populations, and determining the wintering grounds corresponding to the spawning grounds.

[0083] It should be noted that the detailed environmental data of the sea areas where the offshore and offshore groups live, including seasonal changes in water temperature, salinity distribution, water flow speed and direction, seafloor topography and the structure of the marine ecosystem (such as plankton distribution, seafloor sediment characteristics, etc.) are used to verify and correct the spawning grounds initially identified based on the trend of stable isotope changes. For example, if the water temperature near the spawning ground inferred based on stable isotopes does not match the water temperature range suitable for the reproduction of large yellow croaker during the breeding season, or the area lacks the necessary ecological conditions, the judgment of the spawning ground needs to be adjusted.

[0084] After determining a relatively accurate spawning site, the wintering site is determined by combining environmental data and the life history characteristics of large yellow croaker. The environmental conditions of the wintering site are usually related to the spawning site, and are also affected by the physiological needs of large yellow croaker. For example, the wintering site generally needs to have a relatively stable water temperature (within the low temperature range that large yellow croaker can tolerate), sufficient food resources (to maintain the basic energy needs of large yellow croaker in winter), and a suitable habitat (such as suitable water depth, relatively gentle water flow, etc.).

[0085] (4) Determine the farmed type and wild type based on the identification results.

[0086] Based on the identification results, it is clear whether the large yellow croaker is of farmed type or wild type, which is of great significance for subsequent research and management.

[0087] (5) Determine the life path based on the trend of carbon and oxygen stable isotopes changes in the farmed and wild types.

[0088] For farmed yellow croaker, if there is a release, by analyzing the trend of carbon and oxygen stable isotopes before and after the release, we can understand its activity path in the natural environment. After the release, the food source of yellow croaker may gradually change from artificial feed to natural food, and the carbon stable isotope value in its otolith will change accordingly; at the same time, environmental changes (such as natural fluctuations in water temperature and salinity) will also affect the composition of oxygen stable isotopes in otoliths. By tracking these changes, we can determine the activity range, migration route and relationship with wild populations of released farmed yellow croaker in natural waters.

[0089] For wild yellow croaker, its complete life path can be reconstructed based on the changes in its carbon and oxygen stable isotopes at different growth stages and in different regions. Starting from the juvenile period, the stable isotope information recorded in the otoliths can reflect its early living environment (such as the environmental characteristics of the offshore nursery area); as it grows and develops, yellow croaker may migrate, and the isotope changes in its otoliths can track its migration route, including foraging migration from offshore to offshore, migration to spawning grounds during the breeding season, and migration to wintering grounds in winter. Figure 8 For a schematic diagram of a determined life path shown in this application, please refer to Figure 8 The specific area of ​​the spawning grounds, first and second wintering grounds of large yellow croaker in the East China Sea can be clearly inferred. Figure 8 The number 1 in the figure indicates the offshore spawning ground, the number 2 indicates the offshore second year wintering ground, the number 3 indicates the nearshore spawning ground, the number 4 indicates the near offshore first year wintering ground, and the number 5 indicates the nearshore second year wintering ground.

[0090] By dividing the large yellow croaker population more finely (such as offshore and offshore populations), studying its ecological behavior in different marine environments, including the location of key life stages such as reproduction (identification of spawning sites) and wintering (determination of wintering sites), we can gain a deeper understanding of the role and behavior patterns of large yellow croaker in the marine ecosystem. By clarifying the life paths of farmed and wild large yellow croaker, it is helpful to accurately grasp the distribution and dynamic changes of fishery resources, and provide detailed data support for the formulation of reasonable fishery quotas, aquaculture planning and resource protection.

[0091] The method provided in this embodiment determines the first target isotope by variance calculation and contribution analysis, and then identifies whether the large yellow croaker is farmed or wild. This method is more objective and accurate. Compared with traditional morphology or simple labeling methods, the differences in the carbon and oxygen stable isotopes of otoliths affected by the environment and food sources can be used to more accurately divide the groups, avoid misjudgments caused by factors such as small individual morphological differences or loss of labels, and effectively distinguish between farmed and wild large yellow croakers in a complex fishery market environment, which helps to regulate market order and protect wild fishery resources. Further subdividing farmed groups and wild groups, such as judging whether to release farmed groups and judging whether to offshore wild groups. This multi-level classification can provide more detailed group information, which is of great significance for studying the ecological diversity, life history, and role of large yellow croaker in the ecosystem. It can understand the survival and integration of farmed large yellow croaker in the natural environment, and help evaluate the impact of proliferation and release measures on the ecosystem. Cluster analysis using time-related parameters and target isotopes can obtain information about large yellow croaker at different growth stages, which helps to reconstruct the life history of large yellow croaker, including changes in food sources, changes in living environment (such as from nearshore to offshore), and other information, so as to gain a deeper understanding of its ecological adaptability and growth patterns. In addition, after accurately identifying the various types of large yellow croaker populations (farmed / wild, released / not released, offshore / offshore), more reasonable fishing quotas and regional restrictions can be formulated based on the distribution, number and growth of different populations to achieve optimization of fishery resource management.

[0092] Corresponding to the aforementioned embodiment of a method for identifying large yellow croaker populations based on otolith carbon and oxygen stable isotopes, the present application also provides an embodiment of a device for identifying large yellow croaker populations based on otolith carbon and oxygen stable isotopes.

[0093] Fig. 9 This is a schematic diagram of the structure of the first embodiment of the device for identifying large yellow croaker populations based on otolith carbon and oxygen stable isotopes provided in this application. Fig. 9 , the device provided in this embodiment includes an identification module 910, a processing module 920 and an acquisition module 930;

[0094] The identification module 910 is used to calculate the variance of the carbon stable isotope and the oxygen stable isotope in the large yellow croaker sample, and identify the contribution of the carbon stable isotope and the oxygen stable isotope to the identification result based on the variance result;

[0095] The identification module 910 is further used to determine a first target isotope based on the contribution, and identify the source type of the large yellow croaker population to be identified according to the first target isotope, wherein the source type includes farmed and wild;

[0096] The processing module 920 is used to determine the second target isotope for the first sub-population whose source type is the aquaculture type according to the contribution and the first identification type of the first sub-population, cluster the first sub-population according to the second target isotope and the first time-related parameter, and obtain a first identification result corresponding to the first identification type of the first sub-population, where the first identification type is whether to release;

[0097] The processing module 920 is further configured to determine, for the second subpopulation whose source type is the wild type, a third target isotope according to the contribution and the second identification type of the second subpopulation, cluster the second subpopulation according to the third target isotope and a second time-related parameter, and obtain a second identification result corresponding to the second identification type of the second subpopulation, where the second identification type is whether it is near the sea;

[0098] The acquisition module 930 is used to obtain the identification result of the large yellow croaker population to be identified by combining the farming type, the first identification result and the second identification result.

[0099] The device of this embodiment can be used to perform Figure 1 The steps, specific implementation principles and implementation processes of the method embodiment shown are similar and will not be repeated here.

[0100] The implementation process of the functions and effects of each unit in the above-mentioned device is specifically described in the implementation process of the corresponding steps in the above-mentioned method, and will not be repeated here.

[0101] For the device embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment. The device embodiment described above is only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present application scheme. A person of ordinary skill in the art can understand and implement it without paying any creative work.

[0102] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for identifying large yellow croaker populations based on otolith carbon and oxygen stable isotopes, characterized in that: The method comprises: The variances of carbon stable isotopes and oxygen stable isotopes in the large yellow croaker samples are calculated respectively, and the contribution of the carbon stable isotopes and oxygen stable isotopes to the identification results are identified based on the variance results; Determine a first target isotope based on the contribution, and identify the source type of the large yellow croaker population to be identified according to the first target isotope, wherein the source type includes farmed and wild; For the first sub-population whose source type is the aquaculture type, determining the second target isotope according to the contribution and the first identification type of the first sub-population, clustering the first sub-population according to the second target isotope and the first time-related parameter, and obtaining a first identification result corresponding to the first identification type of the first sub-population, where the first identification type is whether to release; For the second subpopulation whose source type is the wild type, determining a third target isotope according to the contribution degree and the second identification type of the second subpopulation, clustering the second subpopulation according to the third target isotope and a second time-related parameter, and obtaining a second identification result corresponding to the second identification type of the second subpopulation, where the second identification type is whether it is near the sea; The identification result of the large yellow croaker population to be identified is obtained by combining the breeding type, the first identification result and the second identification result.

2. The method according to claim 1, characterized in that The method of respectively calculating the variance of the carbon stable isotope and the oxygen stable isotope in the large yellow croaker sample, and identifying the contribution of the carbon stable isotope and the oxygen stable isotope to the identification result based on the variance result, includes: Processing the otoliths of each sample of the large yellow croaker sample to obtain a sample for stable isotope analysis; The stable isotope analysis instrument was used to measure the values ​​of carbon stable isotopes and oxygen stable isotopes at different positions in the sample otoliths; Based on the values, calculate the average values ​​of carbon stable isotopes and oxygen stable isotopes at the same position of all samples; The variance of the carbon stable isotopes and oxygen stable isotopes in the large yellow croaker sample is calculated based on the mean, and the contribution of the carbon stable isotopes and oxygen stable isotopes to the identification results is identified based on the variance analysis results.

3. The method according to claim 2, characterized in that The identifying the contribution of the carbon stable isotope and the oxygen stable isotope to the identification result based on the variance analysis result includes: According to the results of variance analysis, the differences in the proportions of carbon stable isotopes and oxygen stable isotopes under different first identification types and different second identification types were determined; Based on the difference in the proportions and the environmental factors corresponding to the carbon stable isotopes and the oxygen stable isotopes, respectively, the contribution of the carbon stable isotopes and the oxygen stable isotopes to the identification result is identified.

4. The method according to claim 1, characterized in that: The step of determining the first target isotope based on the contribution, and identifying the source type of the large yellow croaker population to be identified according to the first target isotope, comprises: According to the relative size of the contribution, determining that the first target isotope is a carbon stable isotope; Selecting the value of the first target isotope in the first region for clustering; Based on the mean difference of the first target isotope in the clustering results, the source type of the large yellow croaker population to be identified was determined.

5. The method according to claim 1, characterized in that The determining the second target isotope according to the contribution and the first identification type of the first subpopulation includes: identifying the first identification type; The second target isotope is determined based on the difference in contribution ratios of the carbon stable isotope and the oxygen stable isotope in the identified first identification type.

6. The method according to claim 1, characterized in that The first time-related parameters are the slope from the otolith core to the first winter age and the first winter age value; the second time-related parameters are the slope from the otolith core to the first winter age and the slope from the first winter age to the second winter age.

7. The method according to claim 1, characterized in that The clustering of the first subpopulation according to the second target isotope and the first time-related parameter to obtain a first recognition result corresponding to the first recognition type of the first subpopulation includes: acquiring the first time-related parameter and a second target isotope for each individual in the first subpopulation; Perform clustering based on the first time-related parameter and the characteristics of the second target isotope by selecting a clustering method; Based on the clustering results and known fishing information, the differences in the clustering results are analyzed, and the first recognition result is obtained according to the differences.

8. The method according to claim 1, characterized in that The clustering of the second subpopulation according to the third target isotope and the second time-related parameter to obtain a second identification result corresponding to the second identification type of the second subpopulation includes: acquiring the second time-related parameter and a third target isotope of each individual in the second subpopulation; Perform clustering based on the characteristics of the second time-related parameter and the third target isotope by selecting a clustering method; The second identification result is obtained based on the change relationship between the second time-related parameters in the clustering result and the variance difference of the third target isotope.

9. The method according to claim 1, characterized in that: After obtaining the identification result of the large yellow croaker group to be identified by combining the breeding type, the first identification result and the second identification result, the method further comprises: Determine the offshore population and the offshore population based on the identification results; Analyze the trend of stable isotopes in the offshore and offshore populations to identify spawning grounds; Correcting the spawning grounds based on the environmental data of the sea areas where the offshore populations and offshore populations survive, and determining the wintering grounds corresponding to the spawning grounds; Determine the cultured type and the wild type according to the identification result; The life path is determined based on the changing trends of carbon and oxygen stable isotopes of the farmed and wild types.

10. A device for identifying large yellow croaker populations based on otolith carbon and oxygen stable isotopes, characterized in that: The device comprises an identification module, a processing module and an acquisition module; The identification module is used to calculate the variance of the carbon stable isotope and the oxygen stable isotope in the large yellow croaker sample, and identify the contribution of the carbon stable isotope and the oxygen stable isotope to the identification result based on the variance result; The identification module is further used to determine a first target isotope based on the contribution, and identify the source type of the large yellow croaker population to be identified according to the first target isotope, wherein the source type includes farmed and wild; The processing module is used to determine the second target isotope for the first sub-population whose source type is the aquaculture type according to the contribution and the first identification type of the first sub-population, cluster the first sub-population according to the second target isotope and the first time-related parameter, and obtain a first identification result corresponding to the first identification type of the first sub-population, where the first identification type is whether to release; The processing module is further used to determine, for the second subpopulation whose source type is the wild type, a third target isotope according to the contribution and the second identification type of the second subpopulation, cluster the second subpopulation according to the third target isotope and a second time-related parameter, and obtain a second identification result corresponding to the second identification type of the second subpopulation, where the second identification type is whether it is near the sea; The acquisition module is used to obtain the identification result of the large yellow croaker group to be identified by combining the breeding type, the first identification result and the second identification result.

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