Relationship Between Fishing Grounds Of Chilean Jack Mackerel And Environmental Factors In The Southeast Pacific Ocean Based On Geographically Weighted Regression Model And Surplus Yield Model

Chilean jack mackerel(Trachurus murphyi)in the Southeast Pacific one of the important fish species caught by large-scale trawl fishing in my country’s deep-sea fisheries is a relatively important economic fish who has long-distance migration habits in the world,widely distributed the upper-middle waters of the South Pacific.The fishery of Chilean jack mackerel has been among the highest production in the world since its large-scale development in the 1970 s.Chilean jack mackerel fishing grounds have changed because of drastic changes in ocean climate and unreasonable fishing by humans in recent years.The fishing resources are difficult to know.Therefore,it is particularly important to study between temporal and spatial distribution of Chilean jack mackerel fishing grounds and environmental factors.It provide some references for jack mackerel fisheries in the Southeast Pacific.This paper used the catch data of Chilean jack mackerel in the Southeast Pacific from 2012 to 2018,the environment data including sea surface temperature(SST),Chlorophyll-a concentration(Chl-a),sea surface temperature anomaly(SSTA)and sea surface height anomaly(SSHA).The geographically weighted regression model(GWR)was used to analyze the spatial heterogeneity relationship between the fishing ground distribution and environmental factors.Forecast Chilean jack mackerel catch by surplus yield model.The paper used generalized additive model(GAM)to standard CPUE.The paper select the key environmental factors according to the results of GAM model.The paper build different catch forecast models of Chilean jack mackerel based on different models and then verify and appraise the kinds of models.The paper identify the best model to service for Chilean jack mackerel resource assessment and production management.The paper aim to provide more scientific and stable support for the scientific development and utilization of Chilean jack mackerel,It also provides a reference for the future development of Chilean jack mackerel resources in the Southeast Pacific.The main research results are as follows:(1)The relationship between Chilean jack mackerel catch and CPUE.Chilean jack mackerel resources have a decreasing trend from inshore areas to ocean waters.There is a clear correlation between catch and fishing effort and have similar distribution.Chilean jack mackerel in overall monthly changes of catches and CPUE from April to August,2012-2018 has a downward trend basically in the Southeast Pacific.April which has the highest production is the best fishing time for Chilean mackerel in the Southeast Pacific.(2)Temporal and spatial distribution of Chilean jack mackerel fishing grounds.The fishing ground are mainly in the range 20 ～45°S、73～90°W from April to August,2012-2018.The fishing ground reached the northernmost point in 2017.The fishing grounds in 2015 was the most concentrated,which are mainly in the range 34～45°S、77 ～90°W.The fishing grounds move northward month by month,because of the Peruvian cold current flow from south to north.The fishing ground was divided into two parts in August,one part gradually shifted to the northwest and the other shifted to the northeast.(3)The relations between the temporal and spatial distribution of Chilean jack mackerel fishing grounds and marine environmental factors.The sea surface temperature range of Chilean jack mackerel fishing ground is 11～18℃.The optimum sea surface temperature in the fishing area can be expanded to 12～15℃.The range of chlorophyll a concentration in Chilean jack mackerel fishing grounds is 0.05～0.4mg/m3.The optimal range of chlorophyll a concentration in the fishing sea area can be expanded to 0.1～0.25mg/m3.The ranges of SSTA in Chilean jack mackerel fishing grounds is-2 ～2°C.The best ranges of SSTA is 0.5～ 1℃.The ranges of SSHA in the Chilean jack mackerel fishing grounds is-0.05～0.15 m.The abundance of Chilean jack mackerel resources is highest when the ranges of SSHA is 0 ～0.1m.(4)The study standardize the CPUE of Chilean jack mackerel using GAM model.Results show that year,month,longitude,latitude,SST,Chl-a,SSTA and SSHA are all the key factors on the CPUE of Chilean jack mackerel in the Southeast Pacific.This relationship can be described in the order: year,SSTA,SST,month,SSHA,Chl-a,latitude,and longitude.(5)GWR model.The results of the GWR model show that Chilean jack mackerel CPUE and environmental factors SST,Chl-a,SSTA,SSHA and Gear depth have spatial heterogeneity relationship.The influence of sea surface temperature and SSTA on the distribution of Chilean jack mackerel fishing grounds is better than others.SST,Chl-a,SSTA,SSHA and Gear depth have positive effects on CPUE.(6)Environmentally Dependent Surplus Production(EDSP)Model.The paper established three kinds of catch predicting models.SST,Chl-a,SSTA and SSHA were selected as model factors according to the results of GAM model.Catch predicting model based on environmental factors SST,Chl-a,SSTA and SSHA is better than others and its precision is high.Its indicates SST,Chl-a,SSTA and SSHA have a certain impact on the monthly fluctuation of the CPUE of Chilean jack mackerel.