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首页> 外文期刊>ICES Journal of Marine Science >Selectivity and escapement behaviour of five commercial fishery species in standard square- and diamond-mesh codends
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Selectivity and escapement behaviour of five commercial fishery species in standard square- and diamond-mesh codends

机译：五种商业渔业物种在标准正方形和菱形网眼中的选择性和逃逸行为

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摘要

The Danish fishery for Nephrops {Nephrops norvegicus) is often conducted in a mixed-species setting, characterized by high rates of discards of several target species, including Nephrops and cod (Gadus morhua). Experiments were conducted to investigate and compare the selective properties of a standard 70 mm square-mesh codend (standard SMC) and a standard 90 mm diamond-mesh codend (standard DMC). Selectivity estimates for five commercial species are provided for both codends. The standard SMC yielded higher estimates of length at 50% retention/mesh size (hereafter SF) for Nephrops and roundfish than did the standard DMC, but no effect of codend type on SF was found for plaice (Pleuronectes platessa). Moreover, a novel codend cover design allowed assessment of the preferred direction of escapement in the codend. Whiting (Merlangius merlangus) and Nephrops showed pronounced, but opposite, vertical preference in the direction of escapement, with whiting escaping upwards and Nephrops downwards. A significant (p < 0.05) difference in the direction of escapement between the two codends was found for haddock (Melanogrammus aeglefinus) and whiting. Owing to the relatively small catches, the outcome is probably most applicable to Nephrops-directed fisheries under similar conditions, and caution should be taken not to extrapolate the results to other fisheries.
机译：丹麦的Nephrops（Nephrops norvegicus）渔业通常是在混合物种环境中进行的，其特征是抛弃包括Nephrops和鳕鱼（Gadus morhua）在内的几种目标物种的比率很高。进行了实验，以研究和比较标准70毫米方目网眼（标准SMC）和标准90毫米菱眼目网眼（标准DMC）的选择性。提供了两个编码对象对五个商业物种的选择性估计。与标准DMC相比，对于Nephrops和比目鱼，标准SMC在50％保留/网眼尺寸（以下称SF）下产生的长度估计更高，但对于（Pleuronectes platesa），未发现编码区类型对SF的影响。此外，新颖的编码器盖设计允许评估编码器中擒纵机构的首选方向。 Whiting（Merlangius merlangus）和Nephrops在擒纵方向上表现出明显但垂直的偏爱，白向上逃逸，Nephrops向下逃逸。发现黑线鳕（Melanogrammus aeglefinus）和白鳕在两个code的逃逸方向上存在显着差异（p <0.05）。由于渔获量相对较小，因此该结果可能最适用于类似条件下以尼弗罗普斯为导向的渔业，因此应谨慎行事，不要将结果推论到其他渔业中。

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