Atlantic bluefin tuna (ABFT) stocks have been considered overfished over the last decades, especially the western stock, whose main spawning grounds are in the Gulf of Mexico (GoM). Despite the current measures implemented, spawner bycatch by the longline fleet targeting yellowfin tuna (YFT) may explain the lack of recovery of local stocks. This situation demands the implementation of appropriate spatiotemporal management strategies to minimize bluefin bycatch in the GoM, which involves knowledge in depth of its distribution and environmental forcing. Using catch and effort data from the Mexican commercial longline fleet with 100% scientific observer coverage from 1999 to 2012 and satellite derived environmental data, this study investigated the influence of environmental conditions on catch per unit effort (CPUE) of ABFT and YFT. General additive models (GAMs) were fitted using a negative binomial distribution and applying Akaike information criterion (AIC) to select the best model. Bluefin CPUE exhibited a marked seasonality, reaching higher values in February and March while YFT catches occurred throughout the year. Two main locations were identified with higher ABFT bycatch rates, Campeche Bay and the western‐central area of the GoM. Higher ABFT CPUE was significantly associated with areas with negative sea level anomalies and low sea surface temperatures, characteristic of cyclonic eddies. Instead, YFT CPUE showed a lesser environmental influence in its distribution. To our knowledge, the patterns shown in this study provide the first in‐depth approach to understand ABFT bycatch in Mexican waters, which will help in further development of adequate management strategies.

中文翻译：

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在墨西哥湾对墨西哥延绳钓金枪鱼副渔获物的环境影响进行建模

在过去的几十年中，大西洋蓝鳍金枪鱼（ABFT）种群被认为是过度捕捞，特别是西部种群，其主要产卵地在墨西哥湾（GoM）。尽管采取了目前的措施，但针对黄鳍金枪鱼（YFT）的延绳钓船队的产卵副渔获物可能解释了当地种群缺乏恢复的原因。这种情况要求实施适当的时空管理策略，以最大程度地减少GoM中的蓝鳍兼捕，这涉及深入的知识分布和环境强迫。利用墨西哥商业延绳钓船队的捕获量和努力量数据（1999年至2012年具有100％的科学观察员覆盖）和卫星衍生的环境数据，本研究调查了环境条件对ABFT和YFT的单位捕获量（CPUE）的影响。使用负二项式分布并应用Akaike信息准则（AIC）拟合通用加性模型（GAM）以选择最佳模型。蓝鳍CPUE表现出明显的季节性，在2月和3月达到更高的值，而全年发生YFT捕获。确定了ABFT兼捕率较高的两个主要地点，坎佩切湾和GoM的中西部地区。较高的ABFT CPUE与气旋涡特征的负海平面异常和低海表温度地区显着相关。相反，YFT CPUE的分布对环境的影响较小。据我们所知，本研究中显示的模式提供了第一种深入了解墨西哥水域ABFT兼捕的方法，