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Influence of top-panel orientation (lead-ahead) on targeted and incidental catches in a penaeid trawl
Fisheries Research ( IF 2.4 ) Pub Date : 2020-08-01 , DOI: 10.1016/j.fishres.2020.105562
Matt K. Broadhurst , David J. Sterling

Abstract Various, low-cost modifications to the anterior sections of penaeid trawls have been shown to realise significant improvements in species selectivity. This study expands the existing options by quantifying the importance of top-panel orientation relative to the bottom panel (dictated by relative headline and footrope lengths; termed ‘lead-ahead' or ‘lead’) on targeted and incidental catches in an Australian penaeid-trawl fishery. Three trawls were compared in a double rig: (1) the conventional configuration with identical footrope and headline lengths (7.53 m) and a 200-mm diameter buoy attached to the latter (termed the ‘buoyed no-lead trawl’); (2) the same trawl, but with the buoy removed (‘no-lead trawl’); and (3) a trawl with the same headline length as above, but the footrope 1.14× longer, creating lead-ahead (‘lead trawl’). Between 11 and 26 deployments of each configuration were done over six fishing days. Compared to the buoyed no-lead trawl, both the no-lead and lead trawls had greater wing-end spreads and both caught less total bycatch (absolute and standardized weights ha–1 trawled reduced by up to 64 and 48 %, respectively) and fewer individual unwanted species, including jellyfish, Catostylus mosaicus (by up to 61 and 58 %) and southern herring, Herklotsichthys castelnaui (by up to 59 and 43 %). However, only the lead trawl maintained catches of the targeted school prawns, Metapenaeus macleayi. These target catches were reduced by 37 % in the no-lead trawl (without the buoy). The results imply a trawl without lead-ahead requires sufficient headline height to maximise catches of school prawns, but simply introducing lead-ahead and removing the buoy (lowering the headline) can maintain target catches while dramatically reducing bycatch. Similar subtle refinements may have application in other penaeid-trawl fisheries.

中文翻译:

顶板方向(超前)对对虾拖网目标和偶然捕获量的影响

摘要 对对虾拖网前部的各种低成本改造已被证明可以显着提高物种选择性。本研究通过量化顶部面板相对于底部面板的方向(由相对标题和脚绳长度决定;称为“领先”或“领先”)对澳大利亚对虾的目标和偶然捕获的重要性,扩展了现有的选择。拖网渔业。三种拖网在双钻机中进行了比较:(1) 传统配置,具有相同的脚绳和标题长度 (7.53 m) 和连接到后者的 200 毫米直径浮标(称为“带浮标的无铅拖网”);(2) 相同的拖网,但去掉了浮标(“无铅拖网”);(3) 与上述标题长度相同的拖网,但脚绳长 1.14 倍,形成超前('lead trawl')。在六个钓鱼日内完成了每种配置的 11 到 26 次部署。与带浮筒的无铅拖网相比,无铅拖网和有铅拖网的翼端分布更大,总副渔获物更少(ha-1 拖网的绝对重量和标准重量分别减少了 64% 和 48%)和减少个别有害物种,包括水母、Catostylus 马赛克(分别高达 61 % 和 58 %)和南方鲱鱼 Herklotsichthys castelnaui(分别高达 59% 和 43%)。然而,只有铅拖网能够捕获目标学校对虾 Metapenaeus macleayi。在无铅拖网(没有浮标)中,这些目标捕获量减少了 37%。结果表明,没有前导的拖网需要足够的标题高度才能最大限度地捕获小虾,但简单地引入超前并移除浮标(降低标题)可以保持目标捕获量,同时显着减少兼捕。类似的细微改进可能适用于其他对虾拖网渔业。
更新日期:2020-08-01
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