Yu Mengjie, Zhang Liyou, Liu Changdong, Tang Yanli
Fisheries College, Ocean University of China, Qingdao, China.
PeerJ. 2021 Oct 8;9:e12282. doi: 10.7717/peerj.12282. eCollection 2021.
Sustainable development of the important economic species, Asian paddle crab (), has attracted attention in the coastal waters of the Yellow Sea, China. The commonly used round pots are almost nonselective, resulting in severe bycatch of juveniles. In this study, we explored a method to improve the size selectivity for by mounting escape vents on the side panels of each pot. The selectivity of pots with escape vent sizes of 70 mm × 20 mm, 70 mm × 25 mm, 70 mm × 30 mm, and 70 mm × 35 mm was tested using a catch comparison method. The estimated minimum landing size (MLS) of carapace height (27 mm), according to the regulated MLS of carapace length (50 mm), was used as a reference point to explain the results. Significant increases in the size of crabs caught by pots were found with the enlargement of escape vent size (Kruskal-Wallis test, < 0.01). The pots with 70 mm × 20 mm, 70 mm × 25 mm and 70 mm × 30 mm escape vents released nearly 50%, 75% and 95% of undersized individuals, respectively, and these three types of pots retained approximately 90% of legal-sized individuals compared with the control pots without escape vents. The pots with 70 mm × 35 mm escape vents released nearly all undersized individuals, but they also released most legal-sized individuals. Pots with an escape vent size of 70 mm × 30 mm were recommended for the sustainable development of in the Yellow Sea of China. The results of this study reiterate the importance of carapace height for determining the size selectivity, which can serve as a reference to formulate management regulations in the coastal waters of the Yellow Sea, China.
重要经济物种三疣梭子蟹（）的可持续发展在中国黄海沿岸海域受到关注。常用的圆形蟹笼几乎没有选择性，导致幼蟹的兼捕情况严重。在本研究中，我们探索了一种通过在每个蟹笼侧板上安装逃生孔来提高三疣梭子蟹大小选择性的方法。使用渔获物比较法测试了逃生孔尺寸为70毫米×20毫米、70毫米×25毫米、70毫米×30毫米和70毫米×35毫米的蟹笼的选择性。根据规定的头胸甲长度最小上岸尺寸（MLS）（50毫米）估算的头胸甲高度最小上岸尺寸（27毫米）被用作解释结果的参考点。随着逃生孔尺寸的增大，蟹笼捕获的螃蟹尺寸显著增加（Kruskal-Wallis检验，<0.01）。逃生孔尺寸为70毫米×20毫米、70毫米×25毫米和70毫米×30毫米的蟹笼分别放走了近50%、75%和95%的未达尺寸个体，与没有逃生孔的对照蟹笼相比，这三种蟹笼保留了约90%的合法尺寸个体。逃生孔尺寸为70毫米×35毫米的蟹笼放走了几乎所有未达尺寸个体，但也放走了大多数合法尺寸个体。对于中国黄海三疣梭子蟹的可持续发展，建议使用逃生孔尺寸为70毫米×30毫米的蟹笼。本研究结果重申了头胸甲高度对于确定大小选择性的重要性，可为中国黄海沿岸海域制定管理规定提供参考。
