Cod by-catch reducing gear: video observations of fish behavior from Fishing Vessels NEC-MP2000-2 in the Gulf of Maine from 2000-2002 (NEC-CoopRes project)

<p><strong>\"Groundfish Trawl nets Designed to Reduce the Bycatch of Cod\":</strong> Fishing log of experimental tows included in analysis.</p>

<p>Project Leader:Michael Pol Massachusetts Division of Marine Fisheries</p>

<p><em><a href=\"http://northeastconsortium.org/ProjectFileDownload.pm?report_id=92&amp;table=project_report\" target=\"_blank\">final report</a></em></p>

<p>Two experimental trawl net designs substantially reduced catch rates of Atlantic cod Gadus morhua while allowing the targeting of flatfish Pleuronectidae, as compared to a standard net design. The \"Ribas\" and \"topless\" nets both modify the top half of a trawl net; the Ribas net by using large square mesh; the topless net by removing much of the netting in the top square of the net. Seventy pairs of alternate tows showed reductions of cod catch rates (kg/hr) that exceeded 76% for both nets. Catch rates of yellowtail flounder Limanda ferruginea below MLS (~33 cm TL) were more than 74% lower for both nets, compared to a standard flatfish trawl. Reductions of catch rates for winter flounder Pseudopleuronectes americanus below MLS (~33 cm TL) exceeded 61%. Significant reductions occurred in catch above MLS for yellowtail (&gt;32%) and winter flounders (&gt;44%) with some evidence that this reduction was lower for the topless trawl. Underwater video showed cod exiting the nets through the top mesh and through the gap made by the removal of twine. These results demonstrate that separation of Atlantic cod from flatfish is possible and practical. <em>(from final report abstract)</em></p>

<p>associated datasets:<br />
<a href=\"http://nec.whoi.edu/jg/serv/nec/Gear/less_cod_by_log.html0{dir=nec.whoi.edu/jg/dir/NEC/Gear_Technology/,info=nec.whoi.edu/jg/info/NEC/Gear_Technology/less_cod_by_log}\">Cod by-catch reducing gear: fishing log</a></p>

<p><strong>旨在降低鳕鱼兼捕（bycatch）的底层鱼类拖网（Groundfish Trawl nets Designed to Reduce the Bycatch of Cod）</strong>：本分析纳入的试验拖网（trawl net）捕捞日志</p>
<p>项目负责人：迈克尔·波尔（Michael Pol），马萨诸塞州海洋渔业局（Massachusetts Division of Marine Fisheries）</p>
<p><em><a href="http://northeastconsortium.org/ProjectFileDownload.pm?report_id=92&amp;table=project_report" target="_blank">最终报告</a></em></p>
<p>与标准拖网设计相比，两种试验性拖网设计大幅降低了大西洋鳕鱼（Atlantic cod，*Gadus morhua*）的单位捕捞率，同时可针对性捕捞比目鱼（Pleuronectidae科）。“里巴斯网（Ribas net）”与“无顶网（topless net）”均对拖网的上半部分进行改造：里巴斯网采用大型方形网目；无顶网则移除了拖网顶部方形区域的大部分网衣。70组交替拖网试验结果显示，两种拖网的鳕鱼单位捕捞率（千克/小时）降幅均超过76%。</p>
<p>与标准比目鱼拖网相比，两种拖网对低于最小法定体长（Minimum Legal Size, MLS，约33厘米叉长（Total Length, TL））的黄尾比目鱼（*Limanda ferruginea*）的单位捕捞率降低了74%以上。对于低于最小法定体长（MLS，约33厘米叉长）的美洲黄盖鲽（*Pseudopleuronectes americanus*，即冬季比目鱼），两种拖网的单位捕捞率降幅超过61%。</p>
<p>对于超过最小法定体长的黄尾比目鱼（降幅超32%）和冬季比目鱼（降幅超44%），两种拖网的单位捕捞率均出现显著下降，且有证据表明无顶网的降幅更低。水下视频显示，鳕鱼通过顶部网目以及移除网绳形成的空隙从拖网中逃逸。上述结果证明，将大西洋鳕鱼与比目鱼进行分离具备可行性与实用性。<em>（摘自最终报告摘要）</em></p>
<p>关联数据集：<br />
<a href="http://nec.whoi.edu/jg/serv/nec/Gear/less_cod_by_log.html0{dir=nec.whoi.edu/jg/dir/NEC/Gear_Technology/,info=nec.whoi.edu/info/NEC/Gear_Technology/less_cod_by_log}">降低鳕鱼兼捕渔具：捕捞日志</a></p>