Eigaard Ole R, Herrmann Bent, Feekings Jordan P, Krag Ludvig A, Sparrevohn Claus R
National Institute of Aquatic Resources (DTU AQUA), Technical University of Denmark, Kgs. Lyngby, Denmark.
SINTEF Ocean, Trondheim, Norway.
PLoS One. 2021 Jan 28;16(1):e0246076. doi: 10.1371/journal.pone.0246076. eCollection 2021.
A new bycatch reduction device, termed "Excluder", is presented as an alternative to a traditional rigid sorting grid, mandatory in the small-meshed Norway Pout (Trisopterus esmarkii) trawl fishery in the North Sea. The fishery is a high-volume fishery with large vessels, large demersal trawls and catches up to 100 tons per haul of this small forage fish. The Excluder is a 30 m long netting-based sorting system, developed to reduce bycatch (70 mm square meshes) and improving on board gear-handling and safety. The Excluder was tested against a 5.8 m2 standard sorting grid (35 mm bar spacing) in a twin-trawl experiment from the commercial 70 m trawler "S364 Rockall". Catch data were analysed by species and length using the catch comparison method. For all bycatch species analysed, the Excluder had significantly lower catches relative to the grid: herring (21%), whiting (6%), mackerel (5%), American plaice (70%), witch flounder (15%), and lesser silver smelt (71%). For Norway Pout there was a significant increase in the overall catch efficiency of 32%. These results are explained by a 10 cm smaller L50 (the length of fish with 50% probability of being rejected by the sorting system) of the Excluder and a 15 times larger sorting area, which reduces the risk of clogging and loss of function. With these documented effects of improved sorting and target species catch efficiency, implementation of the Excluder would improve sustainability and address two main barriers of the current Norway pout fishery that limit quota capitalization; a tendency for Norway pout to mix with herring and whiting and lowered catch rates from grid-clogging. Additionally, gear-handling and safety on board would be improved.
一种名为“排除器”的新型兼捕减少装置被提出，作为传统刚性分选格栅的替代方案。在北海小网目挪威长鳍鳕（Trisopterus esmarkii）拖网渔业中，传统刚性分选格栅是强制使用的。该渔业是一种大规模渔业，使用大型船只、大型底拖网，每次捕捞这种小型饵料鱼的捕获量可达100吨。排除器是一个基于网的30米长分选系统，旨在减少兼捕（70毫米见方网目）并改善船上渔具操作和安全性。在商业用70米拖网渔船“S364罗卡尔”进行的双拖网实验中，将排除器与一个5.8平方米的标准分选格栅（35毫米杆间距）进行了测试。使用渔获物比较方法按物种和长度对渔获数据进行了分析。对于所有分析的兼捕物种，排除器的渔获量相对于格栅显著更低：鲱鱼（21%）、牙鳕（6%）、鲭鱼（5%）、美洲拟庸鲽（70%）、女巫鲽（15%）和小银汉鱼（71%）。对于挪威长鳍鳕，总体捕捞效率显著提高了32%。这些结果的原因是排除器的L50（被分选系统拒收概率为50%的鱼的长度）小10厘米，分选面积大15倍，这降低了堵塞和功能丧失的风险。鉴于这些已记录的分选改善和目标物种捕捞效率提高的效果，采用排除器将提高可持续性，并解决当前挪威长鳍鳕渔业限制配额资本化的两个主要障碍；挪威长鳍鳕有与鲱鱼和牙鳕混在一起的趋势，以及格栅堵塞导致捕捞率降低。此外，船上的渔具操作和安全性也将得到改善。
