Abstract: To explore the effect of the shape and size of the stow net cod-end mesh on the selectivity of Larimichthys polyactis, three different mesh openings were adopted as 30 mm, 40 mm, 50 mm for diamond-mesh cod-end, and 20 mm, 30 mm, 40 mm for square-mesh cod-end in this study, respectively. 12 at-sea trials were carried out in the Haizhou Bay of the Yellow Sea in autumn 2020, using the covered cod-end method. The Logistic selectivity model was applied in the study, based on the analysis of the composition of the catch and the escape rate of juveniles. The effects of mesh shape and mesh size on the selectivity of Larimichthys polyactis were analyzed. The results showed that: 63 kinds of fish were caught in the experiment, the body length of Larimichthys polyactis ranged from 80 mm to 134 mm, and the average body length was 106 mm. The proportion of the catch in the diamond mesh and square mesh to the total catch was 41.45% and 36.83%, respectively. Under the same mesh size, the release effect of juvenile Larimichthys polyactis with square mesh is better than that of diamond mesh. When the mesh size is 40 mm, the number and mass escape rate of square mesh is 34.53% and 34.39 higher than those of diamond mesh, respectively. The 50% selection body length (L50) of the 30 mm and 40 mm square mesh was 5.93% and 18.84% higher than the corresponding diamond meshes. The juvenile proportion of Larimichthys polyactis is very high, more than 90%, and almost all of them are juvenile fish. Based on the above test results, considering the resource status and production efficiency of Larimichthys polyactis in Haizhou Bay, it is recommended to expand the mesh size of the cod-end net for fishing Larimichthys polyactis from the currently specified diamond mesh of 35 mm to 50 mm of diamond mesh, or square mesh with 40 mm, to achieve the purpose of effectively protecting the juvenile resources of Larimichthys polyactis.

Key words: Stow net, Larimichthys polyactis, diamond mesh, square mesh, selectivity , Haizhou Bay

摘要： 为探究坛子网网囊网目形状和尺寸对小黄鱼（Larimichthys polyactis）选择性的影响，本研究分别设计了3种规格菱形网目（内径30 mm、40 mm、50 mm）和方形网目（内径20 mm、30 mm、40 mm）网囊，采用套网法，于2020年秋季在黄海海州湾海域开展了12次海上试验；在分析渔获物组成和小黄鱼幼鱼逃逸率基础上，应用Logistic选择性模型，分析网目形状和网目尺寸对小黄鱼选择性的影响。结果显示：试验渔获物中共包含不同种类63种；小黄鱼体长范围为80~134 mm，平均体长为106 mm；在菱形网目和方形网目网囊中其渔获量占总渔获量的比例分别为41.45%和36.83%；
相同网目尺寸条件下，方形网目网囊小黄鱼幼鱼释放效果优于菱形网目，网目尺寸为40 mm时，方形网目尾数和质量逃逸率比菱形网目分别高34.53%和34.39%；网目尺寸为30 mm和40 mm的方形网目网囊的50%选择体长（L50）比对应的菱形网目选择性分别高5.93%，18.84%；渔获物组成中，小黄鱼的幼鱼比例非常高，超过90%，基本全为幼鱼。基于上述试验结果，综合考虑海州湾小黄鱼资源状况和生产效益，建议将海州网坛子网捕捞小黄鱼的网囊网目尺寸由现在规定的菱形网目35 mm，扩大为菱形网网目50 mm或方形网网目40 mm，从而达到有效保护小黄鱼幼鱼资源的目的。

关键词: 坛子网, 小黄鱼, 菱形网目, 方形网目, 选择性, 海州湾