Atlantic bluefin tuna (ABT, Thunnus thynnus; Linneaus, 1758) is an ecologically important apex-predator with high commercial value. They were once common off the coast of the United Kingdom (UK), before disappearing in the 1960s. In regions lacking commercial fisheries for ABT, such as the UK and Ireland, spatial data can be scarce. In these cases, sightings and bycatch databases can offset information shortfalls. Here, we document the reappearance of ABT into territorial waters of the UK from 2014 onwards, and increased occurrence off Ireland. We analyse a novel, multi-source dataset comprising occurrence data (2008–2019; 989 sightings and 114 tonnes of bycatch) compiled from a range of sources (scientific surveys, ecotours and fisheries). We show an increasing trend in effort-corrected ABT occurrence in (i) the pelagic ecosystem survey in the western English Channel and Celtic Sea (PELTIC), (ii) an ecotour operator, and (iii) the Irish albacore fishery in on-shelf and off-shelf waters. Sightings of ABT by the PELTIC correlated with modelled abundance estimates of ABT and the Atlantic multidecadal oscillation. These data demonstrate that sightings of ABT have increased off the UK and Ireland since 2014, following the same increasing trend (2010 onwards) as the eastern ABT population.

中文翻译：

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英国和爱尔兰领海中大西洋蓝鳍金枪鱼数量增加的证据

大西洋蓝鳍金枪鱼 (ABT, Thunnus thynnus; Linneaus, 1758) 是一种具有很高商业价值的生态重要顶端捕食者。在 1960 年代消失之前，它们曾经在英国 (UK) 海岸附近很常见。在英国和爱尔兰等缺乏 ABT 商业渔业的地区，空间数据可能稀缺。在这些情况下，目击和兼捕数据库可以弥补信息不足。在这里，我们记录了从 2014 年起 ABT 重新出现在英国领海中，并且在爱尔兰附近发生的情况有所增加。我们分析了一个新颖的多源数据集，其中包括从一系列来源（科学调查、生态旅游和渔业）汇编的事件数据（2008-2019 年；989 次目击事件和 114 吨兼捕）。我们在 (i) 英吉利海峡西部和凯尔特海 (PELTIC) 的远洋生态系统调查、(ii) 生态旅游运营商和 (iii) 爱尔兰长鳍金枪鱼渔业在货架上显示了努力校正 ABT 发生率的增加趋势和现成水域。PELTIC 对 ABT 的目击与 ABT 的模拟丰度估计和大西洋多年代际振荡相关。这些数据表明，自 2014 年以来，英国和爱尔兰的 ABT 目击事件有所增加，其增长趋势与东部 ABT 人口相同（2010 年以后）。