FISHING MECHANISM ANYLYSIS OF SKIPJACK PURSE SEINE FISHERIES

本研究项目从综合的角度对围网捕捞的捕捞机理进行了实验和分析研究，包括鱼类行为、渔具、渔船、渔业海洋学和渔业信息科学等实践和理论研究领域。该项目历时三年，于1991年12月在西热带太平洋海域进行了项目研究巡航，考察船和围网围网两艘船。东京水产大学的Umitaka-MARU船队在渔场进行了CTD和XBT的海洋观测，同期台新丸18号在该渔场作业了30次，以获取气象和海洋条件、船只操纵策略和相应的渔获量数据以及FISHI…动态地球物理的详细观测数据更多的新装备。韩国围网渔船1993年12月的另一次个人巡航也提供了额外的XBT观测数据和海面迁徙鱼群的渔获量数据，这可以与1991年漂流木附着鱼种的渔获量进行很好的比较。根据长期的作业记录，特别注意进行了渔获量分析和目标鱼种的分布。渔获量的季节变化与鳕鱼种群的生态特征有关，已在《东京水产大学学报》上发表。厄尔尼诺对黄鳍金枪鱼渔场的影响是多种多样的，可归因于厄尔尼诺现象。通过对渔获量分布规律的统计分析，在丰产年可观察到密集渔获量，利用模型网具进行的水槽试验可为改进网具设计和作业策略提供参考，并与台新丸18号研究巡航数据得到的网具几何静态值和动态值进行比较。在实际作业中获取围网渔船的振动、纵摇和横摇特性数据，并对其进行处理分析，针对目标物种的行为生理特点，对围网作业的捕捞过程进行了实验和理论研究。金枪鱼的巡航速度被测量为2-3BL/S，而最大速度为15-20BL/S从肌肉活动检查。此外，结合金枪鱼的视觉生理实验，探讨了围网作业环境和中断过程的理论模型，为围网作业策略改进的后续工作提供了成功和失败两个方面的依据。较少

The research project deals with the Experimental and analytical study on the fishing mechanism of skipjack purse seine fisheries, from the view points of the comrehensive approach including both the practical and theoretical research fiels such as fish behavior, fishing gear, fishing boat, fisheries oceanography and the fisheries information sciences. The results for three years project are summarized as follows :The project research cruise was conducted in the western tropic Pacific region on December 1991, with two vessels of the resarch boat and the purse seiner. The Umitaka-Maru, R/T veseel of the Tokyo University of Fisheries, was engaged in the oceanographic observation with CTD and XBT in the fishing ground, where the Taishin-Maru No.18 operated 30 hauls during the same period to aquire the data such as meteological and ocenographic conditions, boat maneuvering strategies and corresponding catch data, as well as the detailed observation data on the dynamic geometies of the fishi … More ng gear. Another individual cruise by the Korean purse seiner in December 1993 also deliver the additional XBT observation data with the catch data for the surface migrating school, which can be available in good comparison to the drift-timber attarated school in 1991.According to the long-term operation records, the catch analysis was conducted in special attention with the ditribution of target school. The seasonal variation of catch in relation to the ecological characteristics of skipjack school was already published in the Jounal of the Tokyo Univerisy of Fisheries. The influence of E1 nino on the fishing ground for yellowfin tuna varied yeary, which can be attributed to the E1 nino phenomena. According to the statistical analysis on the catch distribution pattern, the intensive catch could be observed in the good fishing years.The flume tank experiments with the model gear could offer the informative results on the improvement of gear desining as well as the operation strategy, with the comparison to the static and dynamic values of gear geometry which were obtained from the reserach cruise data of Taishin-Maru No.18. The data on the vibration, pitching and rolling characteristics of purse seiners were obtaind in the practical operation starategy, and has been in processing for analysis.Concerning the behavioral physiology of target species, the experimental and theoretical approach was done with the special focusing on the fish capture process of skipjack purse seining. The cruising speed of skipjack tuna was measured as 2-3 BL/s, while the maximum speed 15-20 BL/s from the muscle activity check. In addition with the visual physiology experiment on skipjack tunas, the theoretical model on the surrounding and interrupting procedure was discussed for the future task on the strategy improvement of purse seine operation in catch failure and success aspects. Less