The Relationship Between Change Mechanism Of Fishing Ground For Jack Mackerel And Ocean Temperature, Salinity In The Southeast Pacific Ocean Based On PLS

Chilean jack mackerel (Trachurus murphyi) inhabits from the equator to52°S andfrom the economic regions of Chile and Pero to the west of the New Zealand as a highlymigratory pelagic species. We began the expedition of the Chilean jack mackerel from2000and have made the industrial productional developments. Environmental factorsare the main factors of the change of the fishing ground. Dagoberto、Bertrand、SHAOGuo-ying、XU Yong-jiu and Li Xian-sen have studied the relationship between catch ofjack mackerel and marine environmental factors, stock assessment, biological charactersand so on. Chilean jack mackerel has the main character of swimming vertically innights. It inhabits in the water of30~80meters. In the former studies, there were onlythe environmental factors of the surface lever. In this paper, from the productiondatabase from2000to2007of Chinese fishing vessels and remote sensing data ofsurface,50meters,100meters of temperature and salinity, dealed with PLS (partialleast-squares regression, PLS)，change mechanism of fishing ground for jack mackerelbased on PLS in the southeast Pacific ocean was studied and we got the most favorablefator of the fishing ground, which was benefit for the expedition of fishing of ourcountry.We used the database from2000~2006to build the mathematical models and thedatabase of2007to check up the models. The region was from29°S~44°S，78°W~112°W. The production database was from the group of Chilean jack mackerel ofShanghai Ocean University, including the working location, time and catching. Thespatial resolution was1°×1°, and we used monthly temporal resolution. Theenvironmental database was from environment database of Columbia University, andthe web is http://iridl. ldeo.columbia.edu. We got six groups of the salinity andtemperature database of the surface level,50m and100m water level. The spatialresolution was1°×1°, and we used monthly temporal resolution.We calculated the environmental factors with CPUE to get the favorable RAI ofthe environmental factors. We used the enveloping method to establish variousenvironment factors and the RAI system of linear equations, and we transformed theenvironment factors to RAI matrix. We built the mathematical models with PLS to getthe main factor and avoided the relationship of the environmental factors. We dealedwith the production database with standardized methods to reduce the time and spatialerrors, and the environment factor calculated with the RAI theory. At the same time, weused many statistical methods to deal with the database before or after building themathematical models. We used the database of2007to check up the models and draw the spatial distribution maps of HSI with Marine explorer. From the results of themodels, change mechanism of fishing ground, the relationship between catch of jackmackerel and marine environmental factors, the assessment of environmental factorsand the feasibility of PLS were studied, then we got the following main conclusions:It was found that the fishing seasons were from June to September. The mostfavorable salinity was from33.6~33.7, and the salinity of September was obviouslylower than other months. The most favorable temperature of surface and50metersranged from13~14℃and it was8~13℃in100meters. The fishing ground turned tonorthwest as the result of west wind drift of the southeast Pacific. The salinity of thesurface lever was the distinctest, which was the result of the nutrient salinity of the upspring. The temperature of50meters was the norm of the change of temperature, whichplayed the secondary role on the fishing ground. PLS model could dispel manycorrelations of environmental factors, and it could explain the28.5%of CPUE perfectly.