热带大西洋金枪鱼延绳钓兼捕鲨鱼种类组成和渔获率及其与表温的关系

根据2007年12月~2008年3月采集的热带大西洋(05°37′~12°01′N、29°00′~36°51′W)金枪鱼延绳钓渔获物数据,分析了金枪鱼延绳钓兼捕鲨鱼的种类组成、渔获量、渔获率及其与表温的关系。本次调查共捕获鲨鱼8种,隶属3目7科7属,总渔获尾数为633 ind,总渔获量达26 837.4 kg,其中大青鲨为主要兼捕种类。各种鲨鱼渔获率平均值在0.003~1.524 ind/1 000 hooks之间,其中大青鲨最高,其值为1.524 ind/1 000 hooks,大眼砂锥齿鲨最低,其值为0.003 ind/1 000 hooks。各种鲨鱼渔获率月变化不明显(ANOVA,P=0.901)。鲨鱼总渔获率和大青鲨渔获率与表温都呈显著性负相关。大青鲨主要出现渔场的表温范围为24.6~25.8℃。

Species composition and catch rate of bycatch sharks captured by tuna longline fishery and their relationship with sea surface temperature in the tropical Atlantic Ocean

Based on catch data collected in the tropical Atlantic Ocean (05°37′N-12°01′N, 29°00′W-36°51′W) from December 2007 to March 2008, the species composition, catch, catch rate of bycatch sharks captured by tuna longline fishery and their relationship with sea surface temperature (SST) are analyzed. Altogether 633 individuals of fish are captured, which belong to 3 orders, 7 families, 7 genera and 8 fish species. The total weight of bycatch sharks is 26837.4kg. And the dominant bycatch shark is blue shark ( Prionace glauca ). Average catch rate of bycatch sharks is 0.003-1.524 individual per 1 000 hooks, of which blue shark is the highest, 1.524 individual per 1 000 hooks, and bigeye sand shark( Odontaspis noronhai ) lowest, 0.003 individual per 1 000 hooks. Catch rate of bycatch sharks shows no obvious monthly fluctuation (ANOVA, P=0.901). An obvious negative correlation is found between SST and catch rate of total bycatch shark and blue shark. The range of SST in the dominant fishing ground where blue sharks appear is 24.6-25.8℃.