延绳钓是中国远洋金枪鱼渔业的主要作业方式,为探讨其渔具结构与性能特征,提高生产效率,笔者于2003年12月~2004年2月期间,在西印度洋5°30′N⁶°30′S,44°00′E~62°00′E一带海域,以国内大型深冷金枪鱼延绳钓典型渔具为对象,研究了不同位置钓钩所处水深、上钓率及渔获效率。结果显示,调查期间钓钩水深分布范围约100~300 m,渔具对大眼金枪鱼上钓率以4⁶组钓钩较高,对黄鳍金枪鱼则以2⁴组钓钩最高。通过减少相邻浮子间钓钩数量至11枚,理论上可使钓钩水深大幅减小,并提高产量22.73%左右。

Longline fishing is the main method in the tuna fishery in China.In order to increase the catch rate of tuna,the gear structure and fishing performance,the hooks' setting depths and the yield efficiency of a tuna longline were studied,based on the practical fishing operation investigation of a typical longline gear on board a Chinese large deep-sea vessel.The marine survey was carried out in the western Indian Ocean(5°30′N～6°30′S,44°00′E～62°00′E) from December 2003 to February 2004.The results indicted that,among the 17 hooks set between 100 to 300 m,the peak yield efficiency occurred among hook sets Nos.4～6 for bigeye tuna and thunnus obesus and hook sets Nos.2～4 for yellowfin tuna and thunnus respectively;By reducing the hook number from 17 to 11 between the two floats,the gear fishing yield could be improved theoretically.