Drifting Fish Aggregating Devices (dFADs) are a major fishing mode for tropical tuna purse seine fisheries worldwide. However, the extent of dFAD use remains poorly understood. We present novel approaches for estimating annual dFAD deployments and number of dFADs monitored by individual vessels, using empirical data and robust estimation procedures. We leveraged observer and logbook data, combined with new dFAD tracking data from the Western and Central Pacific Ocean (WCPO) purse seine fishery, the largest tuna fishery in the world, to evaluate trends in dFAD use across the entire WCPO between 2011 and 2019. Average estimates ranged between 20 000 and 40 000 deployments per year, depending on the methodology, with the total number of deployments appearing relatively stable over the last decade. The median number of active buoys monitored per vessel per day ranged from 45 to 75 depending on the year, well below the current management limit of 350. Our results contrast with other oceans, having fewer buoys monitored per vessel, a unique stable trend, but overall number of deployments two times higher than any other ocean. This study provides a basis for improved monitoring and management of dFAD use in the WCPO, with applicability for other regions.

中文翻译：

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量化世界上最大的金枪鱼渔业使用的漂流鱼聚集设备

漂流鱼聚集装置 (dFAD) 是全球热带金枪鱼围网渔业的主要捕捞方式。然而，人们对 dFAD 的使用程度仍然知之甚少。我们提出了使用经验数据和稳健的估计程序来估计年度 dFAD 部署和单个船舶监测的 dFAD 数量的新方法。我们利用观察员和航海日志数据，结合来自世界上最大的金枪鱼渔业——西太平洋和中太平洋 (WCPO) 围网渔业的新 dFAD 跟踪数据，评估 2011 年至 2019 年间整个 WCPO 的 dFAD 使用趋势。平均估计每年部署 20 000 到 40 000 次，具体取决于方法，过去十年的部署总数似乎相对稳定。根据年份，每艘船每天监测的活动浮标的中位数从 45 到 75 个不等，远低于目前 350 个的管理限制。我们的结果与其他海洋形成鲜明对比，每艘船监测的浮标较少，这是一个独特的稳定趋势，但部署总数是其他任何海洋的两倍。该研究为改进 WCPO 中 dFAD 使用的监测和管理提供了基础，并适用于其他地区。