夏季东海太平洋褶柔鱼群体结构的年际变化

依据2009―2012年连续4年在东海进行的夏季(6月)渔业资源调查资料, 分析了太平样褶柔鱼(Todarodes pacificus)的资源密度、性比、胴长结构、胴长与体质量的关系、初次性成熟胴长等基础生物学参数的年际变化, 阐述了东海太平洋褶柔鱼的群体结构动态。结果表明: (1)夏季东海太平洋褶柔鱼的出现率较高, 但资源密度分布不均。在调查的4年间, 2009年的平均资源密度最高, 2010年最低。(2)各年度的雌雄比例均符合1∶1的关系(P>0.05)。(3)夏季渔汛期的太平样褶柔鱼个体较小。相比较而言, 2012年的优势胴长组最大, 2011年最小。但各年度的优势胴长均小于200 mm。(4)雌、雄个体胴长与体质量的关系符合指数生长曲线, 年间差异极显著(P<0.001)。(5)渔获个体以性未成熟幼体为主, 性腺成熟度随胴长增加而升高。各年度雌性个体的初次性成熟胴长均大于雄性。分析认为, 2009—2012年东海太平洋褶柔鱼夏季渔汛期均以秋、冬生群的性未成熟幼体为主, 夏生群的性成熟大个体较少。各年度太平洋褶柔鱼的生长发育速度以及群体结构有所不同。本研究可为掌握该物种资源的变动规律, 实现资源的合理利用提供基础资料。

Annual variability in population structure of Todarodes pacificus in the East China Sea in summer

Todarodes pacificus using data collected from bottom trawl surveys in the East China Sea during the summers between 2009 and 2012. We estimated the resource density, sex ratio, size structure, and the relationship between mantle length and body weight and mantle length at first maturity in each year. individuals were common but unevenly distributed. The population density was highest in 2009 and lowest in 2010. There was no difference (>0.05) in the abundance of males and females, with the total sex ratio being 1T. pacificus consisted primarily of immature individuals and the dominant mantle length was less than 200 mm. The dominant mantle length was highest in 2012 and lowest in 2011. The relationship between mantle length and body weight was quantified as an exponential growth curve, and there were significant differences among years (<0.05). The stage of maturity increased with mantle length increasing. The mantle length at first maturity in females was larger than in males. In summary, the population of during the summer fishing season consisted primarily of immature individuals from the autumn and winter spawning groups, with a low number of small mature individuals from the summer spawning group. We observed intra annual differences in the rate of growth and development and the population structure. Our results provide a theoretical basis for managing the fishery in the East China Sea during the summer fishing season.