东海中部日本鲭(Scomber japonicus)产卵群体繁殖力特征

The Fecundity of Chub Mackerel(Scomber japonicus) Spawning Stocks in the Central East China Sea

利用2010–2012年春季在东海中部获得的日本鲭产卵群体样品的生物学及繁殖力测定数据,对其群体结构、性腺指数GSI和繁殖力特征进行了研究。结果显示,目前东海中部日本鲭产卵群体年龄结构由1–5龄组成,以2–4龄占优势。日本鲭的个体绝对繁殖力为24770–734684粒,平均为(145575±10067)粒;纯体重相对繁殖力为175–1404 grain/g,平均为(524±24)grain/g;叉长相对繁殖力为102–2070 grain/mm,平均为(483±29)grain/mm。ANOVA分析结果显示,不同叉长组间的性腺指数GSI(F=2.34,P<0.05)、绝对繁殖力(F=8.57,P<0.01)和叉长相对繁殖力(F=5.59,P<0.05)均有显著性差异,但体重相对繁殖力差异不明显(F=2.03,P>0.05)。多元逐步线性回归和非线性回归分析显示,绝对繁殖力与体高、肝重关系密切。为了应对高强度的捕捞压力,日本鲭主要采用降低性成熟年龄,减小最小性成熟叉长和卵径、增加繁殖力等策略来维持种群的延续。

Scomber japonicus is one of the main pelagic fish in the East China Sea and Yellow Sea. It has maintained high yield in recent years. The central East China Sea is one of the major spawning grounds of S. japonicus. To understand the reproductive strategy of S. japonicus under high fishing pressure, we studied the age structure, the gonadosomatic index （GSI） and the fecundity of S. japonicus spawning stocks that were sampled in the central East China Sea in springs of 2010？2012. The data was analyzed with Microsoft Office Excel and SPSS 18.0 statistical software. The current age structure of S. japonicus spawning stocks was from 1 to 5 years, and the dominant age range was from 2 to 4 years. The absolute fecundity varied between 24770 and 734684 grains, with an average of 145575±10067 grains. The relative fecundity to body weight ranged from 175 to 1404 grain/g, with an average of （524±24） grain/g. The relative fecundity to fork length ranged from 102 to 2070 grain /mm, with an average of （483±29） grain/mm. ANOVA analysis showed that there were significant differences in GSI （P〈0.05）, the absolute fecundity （P〈0.01）, and the relative fecundity to fork length （P〈0.05） between different fork length groups, but there was no difference in the relative fecundity to body weight （P〉0.05）. Multiple stepwise linear and non-linear regression analysis showed that the absolute fecundity was closely related to the body height and liver weight. In response to the high fishing pressure, S. japonicus maintain the continuation of stocks by adopting a variety of strategies including earlier sexual maturity age, decrease in the smallest maturity fork length, smaller maturation egg diameter, increase in fertility, etc. In order to have sustainable supply of S. japonicus in the future, we suggest that the fishery administrative department should establish protection zones in spawning grounds and non-fishing periods in the central East China Sea.