Study On The Temperature Mechanism Of Early Resource Occurrence Of Siniperca Kneri In Pearl River

Due to the impact of climate change and human activities,the river fishery resources continue to decline.Siniperca is a carnivorous fish that is at the highest end of the water ecosystem's food chain,and environmental changes have a greater impact on Siniperca,which is distributed in China with 3 genera and 9 species,which are commonly distributed in Heilongjiang,Yangtze,Huaihe,Yellow,Qiantang,and Pearl Rivers.The most common in the Pearl River system are S.kneri and S.scherzeri.Siniperca produces floating eggs,which are multiple spawning fish.The fertilized eggs are hatched from the spawning ground to form a larvae.Studying the response mechanism of Siniperca to environmental stress is of great significance to the protection of that resources and the protection of river ecosystems.In this paper,the S.kneri's larvae were continuously monitored for many years at fixed sampling points in the Gaoyao section of the Pearl River.The relationship between the temperature of the spawning section(water temperature and temperature)and the early supplementary resources of the river section was analyzed.The temperature was studied for the early stage of that.Supplementary impact mechanisms to provide a scientific basis for the protection of Siniperca resourcesThe research results are as follows(1)The research shows that the watersheds of Siniperca include the Songhua River Basin,the Liaohe River Basin,the Huaihe River Basin,the Haihe River Basin,the Yellow River Basin,the Yangtze River Basin,the Southeast Zhuhe River,the Pearl River Basin,etc.The minimum temperature of habitat is-5.1-8.7? of Mohe in the Songhua River Basin,S.kneri is only distributed in the basin south of the Yangtze River,the habitat temperature range is 13.2-25.2?.The main species of the Pearl River water system,Siniperca are S.kneriand S.scherzeri,which are distributed in Beijiang,Xijiang,Pearl River Delta and Hanjiang,Beijiang and Xijiang,respectively.According to the adult fishing data of 6 sampling points in the Pearl River Basin in each quarter of 2015-2016,the Siniperca of Shilong is the most in the six sampling points,and the seasonal variation of Siniperca in the Pearl River Basin is obvious,at the genus level,the highest in winter is0.54%,the lowest in summer is 0.27%,and in individual size,the individual size of Siniperca in winter(181.8kg)is much larger than the individual size of spring(118.5kg)(2)Due to the lack of complete and continuous water temperature of the Zhaoqing sampling point in 2006-2013,the water temperature of the Zhaoqing sampling point is fitted using the continuous measured data of the water temperature of the Dahuang River estuary.After analysis,the water temperature at the sampling point of Zhaoqing and the water temperature of the Dahuang River estuary are obtained.,the fitting equation of the two is y=1.0341x-0.3391)(R2=0.9839),The results can be used to calculate the continuous water temperature of Zhaoqing sampling point from 2006 to 2013 by fitting the equation and the known continuous water temperature of the Dahuang River estuary from 2006 to 2013(3)The first water temperature of S.kneri's larvae in the Gaoyao section of the Pearl River in Zhaoqing is generally above 19?,and the water temperature range at high frequency is 25.2-30.0?.Correlation analysis showed that there was a significant positive correlation between the average water temperature at the monthly and seasonal scales and the corresponding average larval density,with correlation coefficients of 0.385**and 0.656**,respectively.The water temperature at 19? is not the only condition for egg seedlings.The initial egg seedlings of S.kneri are still related to seasonality.For example,most areas of the Pearl River system reach 19? water temperature from mid-March to early April,However,the appearance time of S.kneri's larva still appears in late April to early May(4)Fitting and analyzing the correlation between water temperature and temperature in Zhaoqing,the fitting equation is:y=1.0299x-11.209(R2=0.734),The effect of temperature on the occurrence of S.kneri's larvae showed that the temperature of S.kneri's larvae was above 19? at the first time,the temperature range of high frequency is 25.9-31.1?,and there is a significant positive correlation between the average water temperature and the corresponding average fry density on the daily scale,monthly scale and seasonal scale.The correlation coefficients are 0.153*and 0.542**respectively.And 0.777**.It can be considered that it is feasible to determine the appropriate temperature target for the Siniperca emergence period with temperature.(5)According to the Pearl River S.kneri's larvae occurring at water temperature 19-30.0 ?,temperature 19-31.1 ?,and the background temperature and water temperature data of each basin,the larvae in the Songhua River Basin may appear from June to August;the larvae may appear in the Liaohe River Basin from June to September;the larvae may appear in the Haihe River Basin,the Huaihe River Basin,the Yellow River Basin and the Yangtze River Basin from May to September;the larvae in the southeastern rivers may appear from April to November;this has important reference value for the research and protection of other watershed Siniperca resources.(6)Initially,the KNN model was used to judge whether S.kneri's larvae occurred.The results showed that the single factor temperature could not judge the occurrence of S.kneri's larvae.When the runoff was added as the characteristic attribute,the accuracy of the model was significantly improved,indicating that the KNN model analysis requires multiple factors..Initially establish a regression equation for the degree and temperature of S.kneri's larvae.The formula is:(?)=0.0038 ML2-0.1069ML+0.71(MD is the average monthly density of larvae;ML is the lowest monthly temperature;).The average,maximum and minimum values of the monthly average density and temperature of S.kner's larvae were analyzed in turn.The fitting curve of monthly mean density and average temperature was R2=0.67,P<0.01,and the regression effect was significant.The basic realization of the average temperature can be used to predict the monthly average density of S.kneri's larvae.