Abstract The North Sea brown shrimp (Crangon crangon Linnaeus, 1758) fishery became Marine Stewardship Council (MSC) certified in 2017. As part of the certification, the fishermen proposed to incrementally increase the mesh size of the codend used from 22 mm to 26 mm. As this increase in mesh size could result in a substantial loss of marketable sized brown shrimp (shrimp with total length equal or higher than 50 mm), a combination of a size sorting grid with a bar spacing of 6 mm and a 22 mm codend was proposed by the Danish fishermen as a possible alternative to the increase in codend mesh size. The objective of the proposed gear was to release shrimp smaller than the marketable size before they reach the codend, while potentially limiting the loss of marketable sized shrimp. Therefore, the aim of this study was to investigate the size selective performance of brown shrimp in the above-mentioned gears. The results showed that the grid reduced catches of shrimp under the marketable size of 50 mm. Moreover, the combination of the grid and a 22 mm diamond mesh codend, with an estimated L 50 of 44.9 mm and a selection range of 15.6 mm, had an overall selective performance similar to that of a 26 mm diamond mesh codend, both for shrimps under and above the marketable size.

中文翻译：

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在褐虾（Crangon Crangon Linnaeus，1758 年）束拖网渔业中测试尺寸分选网格

摘要 北海褐虾 (Crangon crangon Linnaeus, 1758) 渔业于 2017 年获得海洋管理委员会 (MSC) 认证。作为认证的一部分，渔民提议将使用的编码器的网眼尺寸从 22 毫米逐步增加到 26 毫米. 由于网格尺寸的这种增加可能导致适销对虾（总长度等于或大于 50 毫米的虾）的大量损失，因此将条间距为 6 毫米的尺寸分选网格和 22 毫米的编码条组合在一起。丹麦渔民提出的一种可能的替代方案来增加代码网的尺寸。提议的渔具的目的是在它们到达编码之前释放小于适销规格的虾，同时可能限制适销规格虾的损失​​。所以，本研究的目的是调查褐虾在上述齿轮中的尺寸选择性能。结果表明，网格减少了可销售规格为 50 毫米的虾的捕获量。此外，网格和 22 毫米菱形网编码器的组合，估计 L 50 为 44.9 毫米，选择范围为 15.6 毫米，具有与 26 毫米菱形网编码器相似的整体选择性能，均适用于虾低于和高于可销售规模。