| 近海张网对黄鲫和小黄鱼的年龄选择性研究 |
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| 引用本文： | 张健,蒋瑞,王忠秋.近海张网对黄鲫和小黄鱼的年龄选择性研究[J].海洋渔业,2016(5):525-532. |
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| 作者姓名： | 张健 蒋瑞 王忠秋 |
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| 作者单位： | 1. 上海海洋大学海洋科学学院，上海 201306; 大洋渔业资源可持续开发教育部重点实验室，上海海洋大学，上海 201306; 国家远洋渔业工程技术研究中心，上海海洋大学，上海 201306;2. 上海海洋大学海洋科学学院,上海,201306 |
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| 基金项目： | 公益性行业(农业)科研专项(201203018)，江苏省水产三新工程项目(2012－35)，国家自然科学基金(31001138) |
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| 摘 要： | 渔具对捕捞对象的年龄选择性对于渔业资源评估等工作是至关重要的,但相关研究较少。使用套网法对网囊网目尺寸分别为35 mm和45 mm的近海张网对黄鲫(Setipinna taty)和小黄鱼(Larimichthys polyactis)的年龄选择性进行分析。数据分析采用2种年龄选择性曲线模型:即估算网囊对个体体长选择性后根据个体生长方程换算和直接使用Logistic曲线代表年龄选择性曲线;通过对渔获体长分布和年龄分布数据的拟合,结果显示,2种年龄选择性曲线均能较好地拟合数据,网囊对黄鲫和小黄鱼的50%选择年龄t50和年龄选择范围SRt均随着网目尺寸的增加而增加,35 mm和45 mm网目尺寸的网囊对黄鲫的t50分别约为4月龄和8月龄,对小黄鱼的t50分别约为0.6龄和1.5龄,明显小于黄鲫和小黄鱼的推荐开捕年龄,反映出目前近海张网渔具网目过小,可能会对幼鱼资源产生不利的影响。
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| 关 键 词： | 张网 年龄选择性 网囊 网目尺寸 黄鲫 小黄鱼 |
Age selectivity of offshore stow nets for hairfin anchovy Setipinna taty and little yellow croaker Larimichthys polyactis |
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| Abstract: | Information of age selection of fishing gears for target species is of great importance in the fishery science research,such as resource stock assessment and so on.Ignorance of age selection information of the fisheries or inappropriate use of selection (length-based or age-based)could lead to bias in research on population construction and biomass assessment.However,there are few researches focusing on the age selectivity.In this paper,we analyzed the age selectivity of Chinese offshore stow nets with 35 mm and 45 mm mesh size codends for hairfin anchovy (Setipinna taty)and little yellow croaker (Larimichthys polyactis)by covered codend experiments in coastal sea.Two different age selectivity curve models were used in analysis. In model 1,the size selectivity of codends for 2 species was estimated by fitting the body length frequencies of catch to logistic selectivity curves and then the age selectivity curves were derived according to Von Bertalanffy growth function.In model 2,logistic curves were fitted by the age frequencies of catch as age selectivity curves directly.The body length and age frequencies of hairfin anchovy and little yellow croaker was fitted to different age selectivity curves in the SELECT model.The results showed that both two age selectivity curves fitted the catch data well,and both age-at-50%-retention(t50 s)and age selection ranges (SRt s )for hairfin anchovy and little yellow croaker increased with increasing of the mesh size.The t50 s of 35 mm and 45 mm mesh size cod-ends are about 4 and 8 months for hairfin anchovy and about 0.6 and 1.5 years for little yellow croaker respectively,which are obviously less than the recommended first-captured ages for hairfin anchovy and little yellow croaker.The age selectivity information reflected that the mesh size of codends of offshore stow nets were undersized excessively at present and might have negative effects on juvenile fish resources. The possible reasons for the difference in the age selectivity between 2 models were also discussed.Taking the distinct growth of different fishes and different treatment success rates for the otolith at different size into account,we suggested that the model 1 would be more suitable for the age selectivity analysis. |
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| Keywords: | stow nets age selectivity cod-end mesh size hairfin anchovy little yellow croaker |
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