Marine megafauna feeding on fishery catches (depredation) or being incidentally caught on fishing gear (bycatch) have become important issues. Their socioeconomic and conservation stakes have been increasingly studied across the world fisheries. They remain understudied in the Pacific Ocean, where longline tuna fisheries reported such interactions. In this study, we provide the first assessment of bycatch and depredation by sharks and odontocetes on longlines in French Polynesia between 2000 and 2018, using data from observers reporting, captains’ logbooks, questionnaires and additional monitoring by authors during three fishing trip. We found that less than 2% of the catch had been depredated, and that shark depredation was more common than odontocete depredation. Shark bycatch was important (20,000 sharks annually, 0.5 shark every 1000 hooks) and odontocete bycatch seemed low (13 occurrences in 18 years), though we identified clear reporting flaws. We discuss the range of uncertainty associated with our assessment, based on the current reporting systems, and the potential consequences of depredation and bycatch on tuna fisheries, as well as on shark and odontocete populations in French Polynesia.

以渔获物为食（掠夺）或被渔具偶然捕获（兼捕）的海洋巨型动物已成为重要问题。它们的社会经济和保护利益在世界各地的渔业中得到了越来越多的研究。它们在太平洋仍然没有得到充分研究，那里的延绳钓金枪鱼渔业报告了这种相互作用。在这项研究中，我们利用来自观察者报告、船长日志、调查问卷和作者在三次捕鱼之旅中的额外监测的数据，对 2000 年至 2018 年间法属波利尼西亚延绳钓上鲨鱼和齿鲸的兼捕和掠夺情况进行了首次评估。我们发现，不到 2% 的渔获物被掠夺，而且鲨鱼的掠夺比齿鲸的掠夺更为常见。鲨鱼兼捕很重要（每年 20,000 条鲨鱼，每 1000 个鱼钩 0.5 条鲨鱼），而齿鲸兼捕似乎很低（18 年来发生 13 次），尽管我们发现了明显的报告缺陷。我们根据当前的报告系统讨论了与我们的评估相关的不确定性范围，以及掠夺和兼捕对金枪鱼渔业以及法属波利尼西亚鲨鱼和齿鲸种群的潜在后果。