Abundance Index in Number by Size Category and Fishing Ground
Abundance Index in Number by Size Category and Fishing Ground
复制标题
按大小类别和渔场划分的数量丰度指数
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
Syoiti Tanaka
中科院分区：
文献类型：
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作者：
Yoshiharu;Matsumiya;Syoiti Tanaka
为了分析秋季日本北方后太平洋秋刀鱼种群的动态，对秋刀鱼起网渔业的渔获量、努力量和各样本的体长组成进行了分析。考虑到不同大小级间的数量动态、体长的年际变化、渔期内的生长和渔场向外海的延伸等情况，计算了不同大小级、不同渔场的数量丰度指数和有效总捕捞强度。对数量丰度指数的季节变化的考察表明，大型鱼类有不断减少的趋势，比其他大小类别更早地从渔场消失。可用种群的总减少系数对有效的总体捕捞强度的回归进行了检验，但在每个大小类别中均未发现任何正相关。渔业对秋刀鱼种群的影响无法估计。鱼群的相继迁入和迁出对数量丰度指数有重要影响。
In order to analyse the dynamics of the saucy population in the Pacific Ocean aff northern Japan in autumn, the catch and effort data of the saury lift net fishery and the length compo sition data for each sample were examined. Taking into consideration such population conditions as the different patterns of the dynamics among size categories, yearly variation of body length, the growth within the fishing season, and the extension of the fishing ground toward offshore, the abundance index in number by size category and fishing ground and the effective overall fishing intensity ere calculated. The examination of the seasonal variation of the abundance index in number showed that the large sized fish have a constantly decreasing tendency and disappear from the fishing ground earlier than other size categories. Regression of the total coefficient of decrease of the available population on the effective overall fishing intensity was examined, but any positive correlation could not be found in every size category. The effect of fishery on the saury population could not be estimated. The abundance index in number was considered to be seriously affected by successive im migration and emigration of fish shoals.