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

本研究是根据2002年渔业技术圆桌会议指导委员会组织的废弃物调查小组进行的。该项目通过船上研究揭示了丹麦围网、围网、帆拖网、底延绳钓、刺网、陷阱、船围网和定置网等8种渔业类型（和歌山、长崎、静冈、千叶和北海道5个地区）的废弃状态。从不同类型渔业甚至同一类型不同区域渔业的数据分析结果表明：1）丢弃率、丢弃率和DUE的统计数据分布（每单位努力的丢弃量）倾向于显示对数正态分布而不是标准正态分布，以及2）如果捕捞作业受到干扰，则看不到数据分布的明显趋势，例如海况和操作故障。作为本项目的国际活动，我们组织了“用标准化方法评价捕捞渔业废弃物的现场调查国际研讨会”，与其他国家分享废弃物问题的信息，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篇演讲，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考察理事会的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).