单 位：
上海海洋大学大洋生物资源开发和利用上海市高校重点实验室;中国水产科学研究院东海水产研究所农业部海洋与河口渔业重点实验室;上海海洋大学大洋渔业资源可持续开发省部共建教育部重点实验室
关键词：
尺寸选择性;对比试验法;对照网囊;网目尺寸;多囊桁拖网
摘 要：
对比作业法是拖网渔具选择性研究中重要的试验方法之一,而对比试验中对照网囊网目的选择至关重要。研究利用多囊桁拖网不同网目尺寸(20、30、35和40mm)网囊捕获的哈氏仿对虾、小黄鱼和棘头梅童鱼渔获体长分布数据,应用几何相似原理,分析过滤性渔具的选择性,并按不同假设条件下(假设1:符合几何相似原理对渔获具有一定的选择性;假设2:对渔获种类没有选择性),探讨如何合理选择对照网囊网目尺寸。结果表明,对照网网囊网目尺寸为20mm,在上述2种假设下,对选择性模型的拟合、简化及对其它网囊的选择性参数没有显著的影响;在考虑了桁拖网渔具各网囊具有相同相对作业强度,以及桁拖网渔具与普通拖网渔具选择性分析方法上的差异等因素后,认为在此项研究中,将小于20mm网目尺寸的网囊视为没有选择性的对照网囊是可行的。
译 名：
Selection of the mesh size of control codend in analysis of size selectivity of multi-codends beam trawls
作 者：
ZHANG Jian1,2,3,SHI Jian-gao4,ZHANG Peng2,SUN Man-chang1 (1.Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources,Ministry of Education,Shanghai Ocean University,Shanghai 201306,China; 2.Key Laboratory of Shanghai Education Commission for Oceanic Fisheries Resources Exploitation,Shanghai Ocean University,Shanghai 201306,China; 3.Key Laboratory of Marine Fishery Ecology and Environment,Ministry of Agriculture,South China Sea Fisheries Research Institute,Chinese Academy of Fishery Sciences,Guangzhou 510300,China; 4.Key Laboratory of Marine and Estuarine Fisheries,Ministry of Agriculture,East China Sea Fisheries Research Institute,Chinese Academy of Fishery Sciences,Shanghai 200090,China)
关键词：
size selectivity; comparative fishing method; control codend; mesh size; multi-codends beam trawl
摘 要：
In comparative fishing method,one of important experimental methods in research on size selectivity of trawls,the control codend mesh size is crucial and a possible upper limit is generally suggested to be half the mesh size of the test codend. However,the suggestion is unavailable when the body size of target specie of trawl is small enough,especially in shrimp or prawn trawl fisheries. In order to discuss how to choose a rational mesh size of control codend,experiments,in which test codends with different mesh sizes (20,30,35 and 40 mm) were rigged in a same multi-codends beam trawl and fished simultaneously,were carried out in Lvsi Fishing Ground. The catch frequency of Parapenaeposis hardwickii,Pseudosciaena polyactis and Collichthys lucida retained by codends were fitted to a selectivity analysis model in which the selectivity curves of different codends were regarded as geometrical similar under two contrary hypotheses (hypothesis 1:the 20 mm mesh size codend is regarded as test codend and selective for catch species and,hypotheses 2:as control codend and non-selective for species). The result demonstrated that the goodness of model fit and the selective parameters of different test codends were not affected significantly by the two contrary hypotheses. Taking the difference in relative fishing intensity and statistical method of analyzing size selection between multi-conends trawl and conventional trawls into account,authors suggest that the assumption of non-selectivity of 20 mm mesh size control codend is acceptable in analysis of size selectivity in the experiemts,which means that the general upper limit of control codend mesh size could be broken.
