南海及临近海域黄鳍金枪鱼渔场时空分布与海表温度的关系

为得到南海及临近海域黄鳍金枪鱼(Thunnus albacores)渔场最适宜栖息海表温度(SST)范围,基于美国国家海洋大气局(NOAA)气候预测中心月平均海表温度(SST)资料,结合中西太平洋渔业委员会(WCPFC)发布的南海及临近海域金枪鱼延绳钓渔业数据,绘制了月平均SST和月平均单位捕捞努力量渔获量(CPUE)的空间叠加图,用于分析南海及临近海域黄鳍金枪鱼渔场CPUE时空分布和SST的关系。结果表明,南海及临近海域黄鳍金枪鱼CPUE在16℃~31℃均有分布。在春季和夏季(3~8月),位于10°~20°N的大部分渔区CPUE较高,其南北侧CPUE较低;而到了秋季和冬季(9月到次年2月),高产渔场区域会向南拓宽。CPUE在各SST区间的散点图呈现出明显的负偏态分布,高CPUE主要集中在26℃~30℃,最高值出现在29℃附近;在22℃~26℃范围内CPUE散点分布较为零散,但在这个范围也会出现相当数量的高CPUE;在22℃以下的CPUE几乎属于低CPUE和零CPUE;零CPUE的平均SST为26.7℃(±3.2℃),低CPUE的平均SST为27.8℃(±2.1℃),高CPUE的平均SST为28.4℃(±1.5℃),高CPUE在各SST区间的分布要比零CPUE和低CPUE更为集中。采用频次分析和经验累积分布函数计算其最适SST范围,得到南海及临近海域黄鳍金枪鱼最适SST为26.9℃~29.4℃。本研究初步得到南海及临近海域黄鳍金枪鱼中心渔场时空分布特征及SST适宜分布区间,可为开展南海及临近海域金枪鱼渔情预报工作提供理论依据和参考。

Relationship between temporal-spatial distribution of yellowfin tuna Thunnus albacares fishing grounds and sea surface temperature in the South China Sea and adjacent waters

South China Sea is an important yellowfin tuna Thunnus albacares longline fishing ground in China. There is little research on relationship between the temporal-spatial distribution of yellowfin tuna fishing grounds and sea surface temperature (SST)environment in the South China Sea and its adjacent waters. Based on the monthly averaged SST data provided by the Climate Prediction Center of the National Oceanic and Atmospheric Administration (CPC/NOAA)and the yellowfin tuna longline fishing catch and effort data of the South China Sea and its adjacent waters published by the Western and Central Pacific Fisheries Commission (WCPFC),we extracted out thirty years (1982-2011)data and plotted spatial overlay maps of averaged SST and catch per unit effort (CPUE)in each month to analyze the potential relationship between yellowfin tuna fishing grounds distribution and SST in the South China Sea and its adjacent waters,and then we adopted the method of frequency analysis and empirical cumulative distribution function (ECDF)to find out the most suitable SST range for yellowfin tunas inhabiting.The results showed that the yellowfin tuna fishing datasets occurred only in areas where SST ranged from 16 ℃ to 30 ℃.In spring and summer (from March to August),most of higher CPUE occurred in areas between 10°N and 20°N,and it tended to decrease outside of these areas.In autumn and winter (from September to February),the fishing grounds extended to more southern areas.A scatter plot remarkably revealed a negative skewed distribution of SST by CPUE.High CPUE mainly occur in areas where SST ranges from 26 ℃ to 30 ℃ and the highest CPUE appears near 29 ℃;the distribution of CPUE tends to be scattered in SST ranging from 22 ℃ to 26 ℃ in which quite a number of high CPUE also occur;below 22 ℃,the CPUE mostly belongs to low CPUE and null CPUE;the SST range of null CPUE,low CPUE and high CPUE are 26 .7 ℃(±3 .2 ℃),27 .8 ℃(± 2.1 ℃)and 28.4 ℃(±1 .5 ℃),which indicates that the high CPUE distribution in SST intervals is more concentrated than the low CPUE and the null CPUE.The SST ranging from 26.9 ℃ to 29.4 ℃ can be regarded as an indication of the most suitable habitat for the yellowfin tunas in the South China Sea and its adjacent waters.The results could provide theoratical evidence and reference for future yellowfin tuna longline production operation as well as fishing ground forecasting in the South China Sea and adjacent waters.