Abundance of Yellowtail Flounder in the Access Area of Closed Area II on Georges Bank in June 2008 from a Large-Scale Petersen Tagging Study

Abundance of Yellowtail Flounder in the access area of Closed Area II on Georges Bank was estimated using a large-scale Petersen tagging experiment. In June 2008, a ten-day mark-recapture experiment was conducted in which nearly 73,000 Yellowtail Flounder were tagged, with nearly 44,000 yellowtail collected in the second sample, including 177 recaptured with tags. Abundance in the study area was estimated to be approximately 18 million for ages 2+ using a variety of conventional and modified models. The Petersen estimates of abundance are significantly greater than contemporary estimates of age-2+ abundance of yellowtail in the entire Georges Bank stock area from the 2013 stock assessment. Sensitivity analyses indicate that the discrepancy in abundance estimates from the tagging study and the stock assessment are robust to a wide range of assumptions. Therefore, the tagging estimates suggest that the stock assessment is substantially underestimating abundance. A mark-recapture experiment using conventional external tags has never been attempted at this large a scale. The ability of this cooperative study to estimate abundance in an area closed to fishing demonstrates the capability of the method for evaluating marine protected areas and complementing conventional stock assessments. 2014 TRAC Transboundary Resources Assessment Committee Working Paper 2014/24 NMFS (National Marine Fisheries Service) NEFSC (Northeast Fisheries Science Center) Submitted Public Domain 1862

本研究采用大规模彼得森（Petersen）标记实验法，对乔治滩（Georges Bank）封闭区域II准入区内的黄尾比目鱼（Yellowtail Flounder）种群丰度开展估算。2008年6月，研究团队实施了为期10天的标记重捕实验：共计标记黄尾比目鱼近73000尾，第二次采样共捕获个体近44000尾，其中177尾为带标记的重捕个体。研究人员结合多种传统模型与改进模型，估算得到研究区域内2龄及以上黄尾比目鱼的种群丰度约为1800万尾。经对比，彼得森法得到的丰度估算值显著高于2013年种群评估中整个乔治滩种群分布区内2龄及以上黄尾比目鱼的同期丰度估算结果。敏感性分析结果显示，标记实验与种群评估间的丰度估算差异，在广泛的假设条件下均保持稳健。据此，本次标记实验的估算结果表明，现有种群评估大幅低估了该种群的丰度。此前，学界从未开展过如此大规模的常规外置标记重捕实验。本合作研究可在禁渔封闭区域内实现种群丰度估算，证实了该方法可用于评估海洋保护区（Marine Protected Area）的生态效应，并可作为常规种群评估的有效补充。本研究成果为2014年跨边界资源评估委员会（Transboundary Resources Assessment Committee, TRAC）工作论文2014/24，由美国国家海洋渔业局（National Marine Fisheries Service, NMFS）下属东北渔业科学中心（Northeast Fisheries Science Center, NEFSC）提交，属于公共领域文献，文档编号1862。