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首页> 外文期刊>Fisheries Research >Separation of fish from Nephrops norvegicus into a two-tier cod-endusing a selection grid
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Separation of fish from Nephrops norvegicus into a two-tier cod-endusing a selection grid

机译：使用选择网格将鱼从Nephrops norvegicus分离成两层鳕鱼

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The legally sized fish by-catch is an important economic component of many Nephrops fisheries. However, the small mesh size typically used by Nephrops trawlers results in many undersized fish being discarded. A selection grid was inserted in a two-tier cod-end in an attempt to separate the target species, Nephrops, from the fish by-catch and to retain the by-catch in the upper cod-end. Good separation would allow fish size selection to be improved by using a larger mesh size in the upper cod-end. The separation properties of grids with two different bar spacings and two lower gaps were investigated. Nephrops, haddock and dab were caught in reasonable numbers. Most small Nephrops passed into the lower cod-end, with the proportion passing into the upper cod-end increasing to between 40 and 70% at carapace lengths of 50 mm. The grids with the larger bar spacing allowed more Nephrops into the lower cod-end, but there was no significant difference in separation between grids for haddock or dab. The proportion of haddock passing into the upper cod-end increased from 60% for 10 cm haddock to 85% for haddock of 20 cm or more. The proportion of dab passing into the upper cod-end increased from 30% for 10 cm dab to 75% for dab of 20 cm or more.
机译：合法大小的鱼副渔获物是许多尼腓罗普渔业的重要经济组成部分。但是，海螯虾拖网渔船通常使用的小网眼尺寸导致许多尺寸过小的鱼被丢弃。在两层的鳕鱼末端插入一个选择网格，以尝试将目标物种Nephrops与鱼副渔获物分离，并将副渔获物保留在上部鳕鱼末端。良好的分离将允许通过在上部鳕鱼端使用较大的网眼尺寸来改进鱼的尺寸选择。研究了具有两个不同的条间距和两个较低的间隙的网格的分离特性。 Nephrops，黑线鳕和dab被捕的数量合理。大多数小型海肾进入鳕鱼的下端，在甲壳长度为50 mm时，进入鳕鱼上端的比例增加到40％至70％。杆间距较大的网格允许更多的Nephrops进入较低的鳕鱼末端，但黑线鳕或dab的网格之间的间距没有显着差异。进入鳕鱼上端的黑线鳕的比例从10厘米黑线鳕的60％增加到20厘米或更大的黑线鳕的85％。进入鳕鱼上端的涂抹物的比例从10 cm涂抹物的30％增加到20 cm或更多的涂抹物的75％。

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