Ifremer, Unité de Sciences et Technologies Halieutiques, Laboratoire de Technologie et Biologie Halieutique, Lorient, France.
Ifremer, Unité de Sciences et Technologies halieutiques, Plouzane, France.
PLoS One. 2020 Jul 8;15(7):e0235368. doi: 10.1371/journal.pone.0235368. eCollection 2020.
Most European fishing fleets will need to drastically reduce their unwanted catches to comply with new rules of the common fisheries policy. A more practical way to avoid increasing on-board sorting time and issues linked to storage capacity is to prevent unwanted catches in the first place. We assessed the selectivity properties of an experimental fishing gear that combined a 100 mm T90 cylinder with 130 meshes in the extension and a 100 mm T90 codend of 33 meshes (experimental gear) compared to a 100 mm diamond mesh extension and codend (control gear) during commercial trips using twin trawls. Analysis of the relative size composition of catches indicated a significantly higher escapement of small fish of several target species (e.g. Lepidorhombus whiffiagonis, Melanogrammus aeglefinus, Raja spp, and Lophius spp) and non-target species (e.g. Capros aper and Gurnards spp) from the T90 experimental trawl compared to the control trawl (n = 49 hauls), resulting in a significant reduction of unwanted catches of Gadidae, Triglidae, and Caproidae. In contrast, non-negligible commercial losses of small grade target gadoid species were observed. Mixed general linear models showed that the proportion of ray, haddock and anglerfish retained per length class decreased with increased tow duration. The T90 experimental gear will perform at a commercial level when targeting monkfish, megrim, rays and large haddock, however fishers are not likely to use this gear when targeting smaller-bodied species such as cephalopods, small haddock, whiting (Merlangius merlangus) and hake (Merluccius merluccius), because the gear is likely to allow large numbers to escape. Selectivity studies often focus on a short list of target species; however, catches of non-target species under quota can be problematic for some fisheries. For example, under the implementation of the Landing Obligation catches of boarfish could choke the French whitefish demersal fisheries in the Celtic sea, as France has no national quota for that species. The device tested constitutes an efficient solution to mitigate catches for such non-target schooling fish.
大多数欧洲捕鱼船队需要大幅减少副渔获物，以遵守共同渔业政策的新规定。避免增加船上分拣时间和与储存能力相关问题的更实际方法是首先防止副渔获物。我们评估了一种实验性渔具的选择性特性，该渔具将 100 毫米 T90 圆柱体与延伸部分中的 130 个网眼和 100 毫米 T90 网囊（33 个网眼）结合在一起，与 100 毫米菱形网延伸和网囊（对照渔具）相比，在使用双拖网进行商业航行期间。对捕获物相对大小组成的分析表明，与对照拖网相比，T90 实验拖网中几种目标物种（例如 Lepidorhombus whiffiagonis、Melanogrammus aeglefinus、Raja spp 和 Lophius spp）和非目标物种（例如 Capros aper 和 Gurnards spp）的小鱼逃逸率明显更高（n = 49 拖网），导致 Gadidae、Triglidae 和 Caproidae 的副渔获物显著减少。相比之下，观察到小等级目标鳕鱼科鱼类的商业损失不可忽视。混合一般线性模型表明，每长度类保留的射线、黑线鳕和钓竿鱼的比例随拖曳持续时间的增加而降低。当目标是鲉鱼、菱鲆、线鳚和大黑线鳕时，T90 实验渔具将在商业水平上运行，但是当目标是较小体型的物种（如头足类、小黑线鳕、鳕鱼（Merlangius merlangus）和鲱鱼（Merluccius merluccius））时，渔民不太可能使用这种渔具，因为这种渔具可能会让大量鱼逃脱。选择性研究通常侧重于一小部分目标物种；然而，在配额下捕获的非目标物种可能对某些渔业造成问题。例如，在着陆义务的实施下，野猪鱼的捕捞可能会使法国凯尔特海的白鱼底栖渔业陷入困境，因为法国没有该物种的国家配额。测试的装置构成了减轻此类非目标群集鱼类捕捞的有效解决方案。
