Fishers have intensively used drifting fish aggregating devices (DFADs) over the last three decades to facilitate their catch of tropical tunas. DFADs increase purse-seine efficiency, potentially increasing tuna fishing mortality. They could also have impacts on tuna natural mortality and reproductive potential, and assessing the consequences of their presence at sea on tuna populations is a challenge. The use of DFADs results in a major increase in the number of floating objects, which are spatially heterogeneous at sea. To date, no converging scientific results exist regarding the effects of DFADs on the large-scale movements and behaviour of tuna, mainly due to the difficulty of disentangling the respective roles of DFADs and environmental factors. Some biological indices show that tuna condition is lower when associated to a floating object than in a free-swimming school. However, it is not clear whether this is the cause or the consequence of the association nor if it has long-term effects on individuals' fitness. Further scientific progress requires (i) the collection of time series of indicators to monitor habitat change, individual behaviour, individual fitness, and population dynamics and (ii) experimental studies to identify the underlying behavioural and biological processes involved in associative behaviour. The extent of the modification of the surface habitat by the massive deployment of DFADs and the current uncertainty of the possible long-term consequences on the individual fitness and dynamics of tuna populations argue for the need for increased awareness of this issue by Regional Fisheries Management Organisations regulating tuna fishing.

中文翻译：

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评估漂流鱼聚集装置对热带金枪鱼行为和生物学影响的挑战

过去三十年来，渔民大量使用漂流鱼聚集装置（DFAD）来促进热带金枪鱼的捕捞。 DFAD 提高了围网效率，可能会增加金枪鱼捕捞死亡率。它们还可能对金枪鱼的自然死亡率和繁殖潜力产生影响，评估它们在海上的存在对金枪鱼种群的影响是一项挑战。 DFAD 的使用导致漂浮物体数量大幅增加，这些漂浮物体在海上具有空间异质性。迄今为止，关于 DFAD 对金枪鱼大规模移动和行为的影响，尚无一致的科学结果，主要是由于很难区分 DFAD 和环境因素各自的作用。一些生物指标表明，金枪鱼在与漂浮物体相关时的状况比在自由游泳学校中的情况要低。然而，尚不清楚这是这种关联的原因还是结果，也不清楚它是否对个人的健康产生长期影响。进一步的科学进步需要（i）收集指标的时间序列来监测栖息地变化、个体行为、个体适应性和种群动态，以及（ii）进行实验研究以确定关联行为所涉及的潜在行为和生物过程。大规模部署 DFAD 对地表栖息地的改变程度以及目前对金枪鱼种群个体适应性和动态可能产生的长期后果的不确定性表明，区域渔业管理组织需要提高对这一问题的认识规范金枪鱼捕捞。