Evaluation of separation performance on selective fishing device for fisheries resources management.

渔业资源管理选择性捕捞装置分离性能评价。

基本信息

批准号：
14560145
负责人：
TOKAI Tadashi
金额：
$ 2.05万
依托单位：
Tokyo University of Marine Science and Technology (2004)東京水産大学 (2002-2003)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

The size selection curve of fine mesh for Anchovy larvae were estimated by using an extended SELECT model for analyzing size frequency distribution constructed from pockets catches and sampling the cod-end catches, and from covered-net experiments. Higher catch volume were decreasing escape opportunities and selectivity.Capture process of clam by dredge was modeled. First, Master curve equation of size selectivity of dredge bagnet for a clam, equilateral Venus Gomphina melanaegis was estimated by using cover-net fishing experiments with test bagnets of several mesh sizes. The size selectivity of dredge bagnet was a kind of contact selection of bagnet mesh. Second, The effect of various tooth-spacing on the contact selection and the net-mouth available selection of a dredge for the equilateral Venus clam Gomphina melanaegis was evaluated by applying a contact-probability model based on the SELECT method to the data of paired-gear tests with a control dredge of 12mm tooth spacing and fou … More r test dredges of tooth spacing 16,20,24,and 35mm. A master selection curve was estimated to be s(R)=exp(-11.23R+4.799)/[1+exp(-11.23R+4.799)], where Ris Id, the ratio of the shell length 1 to the tooth spacing d. The shell width of 50% retention was slightly smaller than the tooth spacing, which means that size selectivity of teeth was a type of contact selection which was dependent on the tooth spacing. Contact probability δ of the clams coming into contact with the teeth were 0.625,0.467,0.563,0.670,and 0.976 for tooth spacing 12,16,20,24,and 35mm, respectively. This indicates that some clams entered the dredge bagnet without contacting the teeth as the sand clogging the tooth spacing carried them into the bagnet. Available selection curve of the dredge net-mouth with teeth was obtained as δ s(R)+1-δ and examined in terms of the minimum landing size of the Venus clam.A method for assessing species-separation performance of size-selective fishing gear is presented. Species composition in catch by selective fishing gear is often discussed to assess the performance of the selective device. However, the catch number (and weight) depends on body size composition in the population when the fishing gear has size selectivity, and thus species composition varies and is not suitable as gear performance index. In fact some selective devices, e.g.mesh panel, grid, and escape-vent have been reported to be size-selective. When a selective device has retention probabilities of body size 1, r_w(l) and r_u(l) for wanted and unwanted species, respectively, separation efficiency p(l_w, 0l_u) between l_w size wanted and l_u-size unwanted species is defined as r_w(l_w)+[1-0r_u(l_u)]-1. The efficiency is 1 when wanted species is completely retained and unwanted is excluded as expected, and is -1 in the exact opposite of the expectation. The equation implied that the separation efficiency is likely to be high as there is larger difference in body size between the two species. Less

鳀鱼幼虫细网的尺寸选择曲线是通过使用扩展的 SELECT 模型来分析由口袋捕获物和对鳕鱼端捕获物采样构建的尺寸频率分布以及覆盖网实验来估计的。较高的捕获量减少了逃逸机会和首先，通过使用测试袋网进行盖网捕捞实验，对挖泥袋网对等边 Venus Gomphina melanaegis 蛤的尺寸选择性的主曲线方程进行了建模。挖泥沙网的尺寸选择性是沙网网孔的一种接触选择。其次，不同齿距对等边金星蛤Gomphina挖泥机的接触选择和网口可用选择的影响。通过将基于 SELECT 方法的接触概率模型应用于配对齿轮测试数据来评估 melanaegis，其中使用 12 毫米齿距的对照挖泥机和 4 个齿距测试挖泥机进行配对测试。主选择曲线估计为 s(R)=exp(-11.23R+4.799)/[1+exp(-11.23R+4.799)]，其中 Ris Id，壳长1与齿距d之比50%保留时的壳宽略小于齿距，这意味着齿的尺寸选择性。是一种取决于齿距的接触选择，对于齿距 12、16、20、24 和 35mm，蛤与齿接触的接触概率 δ 分别为 0.625、0.467、0.563、0.670 和 0.976。这分别表明，一些蛤在没有接触齿的情况下进入了挖泥袋网，因为堵塞齿间距的沙子将它们带入了挖泥袋网中。获得带齿挖泥网口的可用选择曲线为 δ s(R)+1-δ 并根据金星蛤的最小着陆尺寸进行检验。一种评估尺寸分离性能的方法。通常会讨论选择性渔具捕获的物种组成，以评估选择性装置的性能。然而，当渔具具有尺寸选择性时，捕获数量（和重量）取决于种群的体型组成。，因此物种组成发生变化并且是不适合作为齿轮性能指标。事实上，当选择性装置的主体尺寸为 1、r_w(l) 和 r_u 时，一些选择性装置（例如网状面板、网格和逃逸通风口）具有尺寸选择性。 (l) 分别对于想要的和不需要的物种，l_w 大小的想要的物种和 l_u 大小的不需要的物种之间的分离效率 p(l_w, 0l_u) 定义为r_w(l_w)+[1-0r_u(l_u)]-1 当想要的物种被完全保留并且不需要的物种被排除时，效率为 1，与期望完全相反。由于两个物种之间的体型差异较大，因此分离效率可能较高。