Effects Of Environmental Factors On The Distribution Of Bigeye Tuna In The Low Latitudes Of The Eastern Pacific Ocean

In the past half century,with the advancement of science and technology,the world pelagic fishery has developed rapidly.In the world pelagic fishery,the tuna fishery has considerable development prospects and is almost the most important development industry.Among the tuna fisheries,bigeye tuna is the most important fish,and its annual output accounts for more than 70% of the total annual catch of tuna fishery.The development of large-eyed tuna fishery is based on the development of fishing technology and forecasting technology.At present,the ocean fishing forecasting technology is still in the development stage with low accuracy.In order to improve the prediction accuracy of bigeye tuna fishery,scholars at home and abroad have studied the relationship between marine environmental factors and the distribution of bigeye tuna resources.However,due to the difficulty in collecting data of deep ocean environmental elements in the ocean,the use of measured data to study the relationship between the marine environment of different depths of water and the distribution of bigeye tuna fishery is still lacking.In order to more comprehensively study the influence of Marine environment on the distribution of bluefin tuna,this paper combined the surface and deep Marine environment to study the distribution of bigeye tuna.Based on fishery catches,in situ ocean environment data in the low latitude Pacific Ocean from June to August 2010,and combined with satellite remote sensing data,Argo buoy data,we studied and analyzed the effect of different depths ocean temperature on the distribution of tuna.The results show that: There are different suitable temperature ranges for bigeye tuna in different depths of the ocean.The ranges in the depths of 0m,50 m,100m,150 m,200m,300 m are 25.5~28.4 ?,26.1~28.5 ?,25.4~27.5 ?,21.0~23.8 ?,16.3~21.4 ?,10.6~11.8? separately.The correlation between catches and water temperature at the depth of 0~50 m is the strongest.With the condition of satisfying the upper water temperature,the distribution of bigeye tuna catches is affected by the horizontal gradient of sea water temperature.The high catches sea area has obvious horizontal temperature front at the depth of 150~200 m,and the horizontal gradient of temperature is around 0.019~0.020 ?/km.The optimum range of vertical gradient of ocean temperature for bigeye tuna is-0.086~-0.068 ?/m,and the highest catch of bigeye tuna was found at ocean temperature with a vertical gradient of-0.074?/m.The sea surface height in the high catch area(CPUE>2.14,catch per unit effort,CPUE)is concentrated in the range of 40 to 62 cm.Meanwhile,the depth of 20? isotherm in high catches area mainly concentrates near the depth of 150 m(the range of the depth varies from 100 m to 170 m).Overall,the catches decrease with the increase of thermocline depth.This study has important significance to improve the accuracy of prediction of the tuna fisheries.