We evaluated the isoline distribution of thermocline characteristics (the upper and lower boundary temper-atures and depths)in the yellowfin tuna (Thunnus albacares )fishing grounds in Western and Central Pacific O-cean.We plotted the thermocline characteristics contour on a spatial overlay map using data collected on a monthly basis from Argo buoys and monthly CPUE (catch per unit effort)from yellowfin tuna longlines from the Western and Central Pacific Fisheries Commission (WCPFC).In addition,frequency analysis and the empirical cumulative distribution function (ECDF)were used to calculate the optimum ranges for the thermocline characteristics of the central fishing grounds.Our analysis suggested that there were significant seasonal variations in the upper bounda-ry temperature and depth of the thermocline in the central fishing grounds,which significantly influenced the tem-poral and spatial distribution of the yellowfin tuna population.However,the lower boundary temperature and depth of thermocline has little seasonal variation.The overlay maps suggest that the central fishing grounds were ob-served in areas where the upper boundary depth of thermocline was deeper,and south-north moved follow by ther-mocline.The values between 70 and 100 m in the east zonal areas of New Guinea,and the central fishing grounds were found all year.The fishing grounds distributed where the upper boundary temperature of the thermocline was higher than 26℃,but CPUE was lower than Q3 while temperature higher than 30℃.The fishing grounds located between the two high value shape of the lower boundary depth of thermocline,if the depth was more than 300 m or less than 150 m,the CPUE tended to be low.The lower boundary temperature of the thermocline in the fishing grounds was lower than 13℃ all year in the equatorial zone.Conversely,if the temperature was higher than 17℃, the hooking rates are very low.Frequency analysis and the empirical cumulative distribution function (ECDF)were used to calculate the optimum range of thermocline characteristics.The optimum depth range of the upper bounda-ry temperature and depth were 27-29.9℃ and 70-109 m .The optimum depth range of the lower boundary and the lower boundary temperature were 250-299 m and 11-13.9℃,respectively.The results were confirmed by u-sing the Kolmogorov-Smirnov test.A preliminarily indication of the optimum distribution interval and seasonal change characteristics of each thermocline in the longline central fishing ground of yellowfin tuna was obtained in this paper.The conclusion could provide a reference for improving the efficiency of yellowfin tuna longline fishing and aid tuna resource management in Western and Central Pacific Ocean.%为了解热带中西太平洋延绳钓黄鳍金枪鱼（Thunnus albacares ）适宜的温跃层参数分布区间，采用 Argo 浮标温度信息和中西太平洋渔业委员会（The Western and Central Pacific Fisheries Commis-sion，WCPFC）的黄鳍金枪鱼延绳钓渔获数据，绘制了热带中西太平洋月平均温跃层特征参数和月平均 CPUE 的空间叠加图，用于分析热带中西太平洋黄鳍金枪鱼中心渔场时空分布和温跃层特征参数间的关系。分析结果表明：热带中西太平洋温跃层上界深度、温度具有明显的季节性变化，而温跃层下界深度、温度季节性变化不明显，黄鳍金枪鱼中心渔场分布和温跃层季节性变化有关。全年中心渔场的位置分布在温跃层上界深度高值区域，随温跃层上界深度高值区域季节性南北移动。在新几内亚以东纬向区域（5°N～10°S，150°E～170°W）上界深度值全年都在70～100 m 之间，全年都是延绳钓黄鳍金枪鱼中心渔场。中心渔场上界温度多在26℃以上，但是在上界温度超过30℃区域，CPUE 值较小。中心渔场主要分布在温跃层下界深度两条高值带之间区域，在温跃层下界深度超过300 m 和小于150 m 区域，CPUE 值均偏低。中心渔场主要分布在下界温度低于13℃区域，下界温度超过17℃难以形成中心渔场。频次分析和经验累积分布函数计算其适宜温跃层特征参数分布，得出中西太平洋黄鳍金枪鱼适宜的温跃层上界温度和深度分别是27～29．9℃和70～109 m；适宜的温跃层下界温度和深度分别是11～13．9℃和250～299 m 。文章初步得出中西太平洋黄鳍金枪鱼中心渔场温跃层各特征参数的适宜分布区间及季节变化特征，为我国金枪鱼实际生产作业提供技术支持。
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