南海北部近海蓝圆鲹渔业生物学特征研究

Biological characteristics of Decapterus maruadsi in the northern South China Sea

为加深对南海北部蓝圆鲹(Decapterus maruadsi)种群的结构特征认识,根据2014—2017年南海北部底拖网调查中蓝圆鲹的生物学数据,对该区域内蓝圆鲹群体的体长与体质量、性腺成熟度、摄食等级等生物学特征的组成与季节变化进行初步研究。结果显示,南海北部蓝圆鲹体长范围78~248 mm,平均体长146 mm,优势体长121~150 mm;体质量范围7.9~290.0 g,平均体质量52.0 g,优势体质量21.0~60.0 g;雌雄个体体长间存在显著性差异(P<0.05)。体长与体质量的关系为W=8×10^(-6)L^(3.1312),生长参数b=3.1312,接近等速生长。雌雄性比1.5∶1。性腺成熟度以Ⅱ期为主,各月份均有性成熟的个体,冬、春季节性成熟个体都超过50%,为主要繁殖季节。雌性初次性成熟体长为170.9 mm。摄食等级以2级为主,随着体长的增加,摄食水平有升高的趋势。跟历史资料比较发现,南海北部蓝圆鲹性早熟、种群结构小型化的特征没有改变。

To deepen the understanding of population characteristics of Decapterus maruadsi in the northern South China Sea,we evaluated the compositional and seasonal changes of the biological characteristics such as body length and weight,gonadal maturity,and feeding stage of Decapterus maruadsi.The biological data were collected from the bottom trawl surveys in the northern South China Sea from 2014 to 2017.The results showed that the body length ranged from 78 mm to 248 mm,the average was 146 mm,and the dominant body length group ranged from 121 mm to 150 mm;the body weight ranged from 7.9 g to 290.0 g,the average was 52.0 g,and the dominant body weight group range from 21.0 to 60.0 g.There were significant differences in body length between male and female individuals(P<0.05).The relationship between body length and body weight were W=8×10^(-6)L^(3.1312),and the growth parameter b=3.1312,close to the constant growth rate.The sex ratio was 1.5∶1.Gonad maturity was a priority inⅡperiod,each season had individuals of sexual maturity,in winter and spring seasonal mature individuals were more than 50%in number,thus they were the main breeding seasons.The body length at the first maturity of female individuals was 170.9 mm,and the feeding stage was mainly level 2.With the increase of body length,the feeding stage tended to increase.Compared with the historical data,we found that the characteristics of Decapterus maruadsi in the north South China Sea,such as precocity and small population structure,had not changed.Therefore,it is suggested to continue to reduce the fishing intensity,and implement strict summer moratorium of marine fishing,the minimum catchable specification and the quota fishing system for the stock protection.