IMAR-Institute of Marine Research, Departamento de Oceanografia e Pescas, Universidade dos Açores, Horta, Portugal.
Institute of Marine Sciences-Okeanos,-Departamento de Oceanografia e Pescas, Universidade dos Açores, Horta, Portugal.
PLoS One. 2023 Oct 19;18(10):e0292727. doi: 10.1371/journal.pone.0292727. eCollection 2023.
The threat of population declines caused by pelagic longline fisheries in the Atlantic has increased the concern to find strategies that minimize the bycatch and mortality of non-target marine animals. Gear modification, such as the use of circle hooks instead of conventional J-hooks, has been identified as an effective bycatch reduction strategy in different pelagic longline fisheries around the world. This study aimed to verify the effectiveness of the use of circle hooks by quantifying catch rates, relative size selectivity, and anatomical hooking position for the most common target species (swordfish, Xiphias gladius, and blue shark, Prionace glauca), and some bycatch species (loggerhead sea turtles, Caretta caretta, and shortfin mako, Isurus oxyrinchus) caught by the Azorean longline fishing fleet. The trial was conducted for five consecutive years (2000-2004) using eight different types of hooks. In general, the blue shark catches using circle hooks were significantly higher compared to J (Mustad 9/0). The circle hooks also showed high probabilities of catching juvenile blue sharks. Conversely, the circle hooks were efficient in reducing the loggerhead sea turtle bycatch and were related to fewer catches of small sea turtle individuals. The use of circle hooks was also associated with reduced swordfish catches compared to J (Mustad 9/0), and the effect of hook types on length at capture was only significant for Circle (L. & P. 18/0-CLP18) and Ringed Tuna (RT). No significant differences were observed comparing hook type to either catch rates or size selectivity for shortfin mako. Additionally, circle hooks were more likely to lodge in the mouth than in deeper anatomical positions, when compared to J (Mustad 9/0), for the four species analysed. The present study demonstrated that the use of circle hooks could mitigate the impact of the pelagic longline fisheries in the Azores by decreasing the bycatch of sea turtles and reducing animal injuries caused by deep hooking.
由于北大西洋延绳钓渔业导致的种群数量下降的威胁，增加了寻找策略以最大限度地减少非目标海洋动物的兼捕和死亡率的关注。渔具改良，例如使用圆形鱼钩而不是传统的 J 型钩，已被确定为世界各地不同的延绳钓渔业减少兼捕的有效策略。本研究旨在通过量化最常见目标物种（剑鱼、Xiphias gladius 和蓝鲨、Prionace glauca）和一些兼捕物种（红海龟、Caretta caretta 和短鳍灰鲭鲨、Isurus oxyrinchus）的捕获率、相对大小选择性和解剖钩刺位置，来验证圆形鱼钩的有效性。该试验连续五年（2000-2004 年）进行，使用了八种不同类型的鱼钩。总体而言，与 J 型钩（Mustad 9/0）相比，使用圆形钩捕捉的蓝鲨数量明显更高。圆形钩也显示出捕捉幼年蓝鲨的高概率。相反，圆形钩在减少红海龟兼捕方面非常有效，并且与小海龟个体的捕获量较少有关。与 J 型钩（Mustad 9/0）相比，使用圆形钩还与剑鱼捕获量减少有关，并且钩型对捕获时长度的影响仅对圆形钩（L. & P. 18/0-CLP18）和环金枪鱼（RT）显著。在比较短鳍灰鲭鲨的捕获率或大小选择性时，没有观察到钩型之间的显著差异。此外，与 J 型钩（Mustad 9/0）相比，当比较四种分析物种时，圆形钩更容易钩在口腔而不是更深的解剖位置。本研究表明，使用圆形鱼钩可以通过减少海龟的兼捕和减少深钩造成的动物伤害，减轻亚速尔群岛延绳钓渔业的影响。
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