大西洋中上层延绳钓渔业造成的人口下降的威胁增加了人们对寻找将非目标海洋动物的副渔获物和死亡率降至最低的战略的关注。齿轮改装,例如使用圆形挂钩代替传统的J形挂钩,已被确定为世界各地不同远洋延绳钓渔业的有效减少副渔获物战略。本研究旨在通过量化渔获率来验证使用圆钩的有效性,相对尺寸选择性,和最常见目标物种的解剖钩位置(箭鱼,剑兰,还有蓝鲨,Prionaceglauca),和一些副渔获物种(黑头海龟,香烟护理,和短鳍马科,Isurusoxyrinchus)被Azorean延绳钓捕鱼船队捕获。该试验连续五年(2000-2004年)使用八种不同类型的钩子进行。总的来说,与J(Mustad9/0)相比,使用圆形钩的蓝鲨捕捞量明显更高。圆形钩子还显示出很高的捕获幼年蓝鲨的可能性。相反,圆形钩子有效地减少了斑头海龟的副渔获物,并且与小海龟个体的渔获物减少有关。与J(Mustad9/0)相比,圆钩的使用也与箭鱼捕获量减少有关,钩类型对捕获长度的影响仅对Circle(L.&P.18/0-CLP18)和环形金枪鱼(RT)。将钩子类型与短鳍mako的捕获率或尺寸选择性进行比较,没有观察到显着差异。此外,圆形钩比更深的解剖位置更容易停留在嘴里,与J(Mustad9/0)相比,分析的四个物种。本研究表明,使用圆钩可以通过减少海龟的副渔获物和减少深钩引起的动物伤害来减轻亚速尔群岛中上层延绳钓渔业的影响。
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.