北太平洋金枪鱼延绳钓钓钩垂直分布及浸泡时间对渔获物的影响

根据中国金枪鱼延绳钓渔业观察员于2018年9-12月在北太平洋公海(150°W-164°W,30°N-37°N)采集的金枪鱼延绳钓渔获数据,分析了钓钩的垂直分布及浸泡时间与渔获物之间的关系。结果表明,11种主要渔获物钓获深度差异很大,鲣(Katsuwonus pelamis)的平均钓获深度最浅,大青鲨(Prionace glauca)最深;除大青鲨和帆蜥鱼(Alepisaurus ferox)外,其他兼捕鱼类的钓钩深度分布与大眼金枪鱼(Thunnus obesus,目标鱼种)之间差异显著;随着浸泡时间的增加,总渔获率呈先增加后下降的趋势,10~14 h内渔获率较高,且在第10小时达到峰值1.44尾·(千钩·h)-1];浸泡时间在10~16 h内大眼金枪鱼的渔获率较高,且在第11小时达到峰值0.45尾·(千钩·h)-1]。研究结果可为渔业生产和CPUE的标椎化提供参考,为制定有效减少兼捕鱼种的管理措施提供科学依据。

Effects of vertical distribution and soaking time of tuna longline fishing hooks on catches in North Pacific

We investigated the relationship between vertical distribution and soaking time of hooks and catches collected in the North Pacific(150°W−164°W,30°N−37°N)from September to December 2018 by the Chinese Longline Fisheries Observer Programme.The results show that the depth ranges of 11 main species were different.The species with the shallowest and deepest depths were Katsuwonus pelamis and Prionace glauca,respectively.Except for Prionace glauca and Alepisaurus ferox,the mean depth and depth distributions of bycatch species were significantly different from those of the targeted Thunnus obesus.With the increase of soaking time,the total catch rate firstly increased and then decreased.Besides,it was higher in 10~14 h,which reached the maximum value at 10th hour1.44 ind·(1000 hooks·h)−1].The catch rate of bigeye tuna was higher in 10~16 h,which reached the maximum value at 11th hour0.45 ind·(1000 hooks·h)−1].The results provide references for the fishing strategy and catch per unit effort(CPUE)standardization as well as formulating effective management measures to reduce the bycatch species.