Field Survey for Evaluation of Discards in Capture Fisheries with a Standardized Method

本项目研究是根据2002年渔业技术圆桌会议渔业技术研讨会指导委员会组织的弃物调查小组进行的。本项目通过船上调研，揭示了丹麦围网、围网、拖网、底长线、刺网、陷阱、船围网、套网等8种渔场（和歌山、长崎、静冈、千叶、北海道5个地区）的废弃状况。对不同类型渔场乃至不同区域同一渔场的研究结果表明：1)丢弃率、丢弃比和单位努力丢弃量的统计数据分布倾向于呈对数正态分布，而不是标准正态分布；2)在受到海况、作业故障等干扰的情况下，数据分布没有明显的趋势。根据研究人员的经验，提出废品率在实际中是有用的。作为该项目的一项国际活动，我们组织了“标准化捕捞渔业弃置物实地调查评估国际研讨会”，与其他国家分享有关弃置物问题的信息，并在他们的国家推广我们的标准化调查方法。共有12个国家的研究人员参加了研讨会，并发表了11场演讲，其中包括国际渔业研究所、东南亚渔业发展中心和国际海洋探索理事会的2篇论文。

This project study is carried out based on the discard survey group organized in the Steering Committee for the Colloquium on Fishing Technology Round Table Meeting for Fishing Technology on 2002. This project revealed the discard state in 8 types of fisheries, including Danish seine, purse seine, sail-trawl, bottom long line, gillnet, trap, boat seine, and set net (5 regions in Wakayama, Nagasaki, Shizuoka, Chiba and Hokkaido) through onboard research. The results obtained from various types of fisheries and even same kind of fisheries but different regions indicated that 1) statistical data distributions of the discard rate, discard ration and DPUE (discard per unit effort) tend to show a logarithmic normal distribution rather than a standard normal distribution and 2) clear trend of the data distribution is not seen if fishing operation is disturbed, such as sea condition and operational troubles. It is also suggested that discard rate is practically useful based on the researcher's experiences.As an international activity of this project, we organized the "International seminar on Field Survey for Evaluation of Discards in Capture Fisheries with a standardized method" to share the information on the discard issue with other country and to promote our standardized method for the survey in their country. A total of 12 countries researcher participated to the seminar and 11 talks were presented including 2 papers from international fisheries institute, SEAFDEC (Southeast Asian Fisheries Development Center) and ICES (International Council for the Exploration on the Sea).