【摘要】 为确定南海张网最小网目尺寸的适宜性,使用套网法开展了2015年春夏两季黄茅海河口双桩竖杆张网网囊网目选择性试验。根据相对重要性指数(IRI),确定凤鲚(Coilia mystus)作为选择性研究的指标种,使用Logistic曲线,求得不同网囊网目尺寸下的体长选择性曲线,并运用极大似然估计法获得曲线参数。结果表明:春季试验中,在25 mm、35 mm网囊网目下凤鲚的L0.5分别为107.84 mm和114.61 mm;夏季试验中,25mm、30 mm和35 mm网囊网目下的L0.5分别为77.35 mm、88.87 mm和99.91 mm。随着网目尺寸的增大,凤鲚的L0.5和选择范围SR也随之增大。同一网目尺寸下不同季节凤鲚的L0.5差异较大,但不同季节根据L0.5和网目大小关系式计算得出的最小网目尺寸差异不大,分别为42.95 mm和43.87 mm。研究表明,目前35 mm的最小网目尺寸标准不能满足该海域张网渔业资源保护的需求。更多还原

【Abstract】 In order to determine the suitability of the minimum mesh size of stow net in the South China Sea,the selectivity of codend mesh of double stake net was studied by using covered net method in Huangmaohai Estuary in April and August of 2015. Coilia mystus is the main fishing target in the area by the index of relative importance( IRI). Using the catch data of the fishing target,different mesh sizes selectivity curves of them have been drawn by using Logistic curves as a selectivity model. Parameters of selectivity are estimated according to the maximum likelihood method. The results of the experiments indicate that when the mesh size is 25 mm and 35 mm in spring,its L0. 5 is 107. 84 mm and 114. 61 mm,respectively; when the mesh size is25 mm,30 mm and 35 mm in summer,its L0. 5 is 77. 35 mm,88. 87 mm and 99. 91 mm,respectively. With the increase of the mesh size of stow net,the L0. 5 and SR of Coilia mystus increase. The L0. 5 of Coilia mystus is different with the same mesh size between spring and summer,while the minimum mesh size calculated according to the relationship between L0. 5 and mesh size remains basically the same in all seasons,which is42. 95 mm and 43. 87 mm respectively. Based on the results,we conclude that the minimum mesh size of 35 mm cannot meet the demand of fishery resources protection in Huangmaohai Estuary.更多还原