东海南部鲐鱼生物学特性的初步研究

本文对东海南部的鲐鲹鱼类的叉长、体重及性腺成熟度等进行了初步分析,认为1999年5月份东海南部鲐鱼优势叉长组为26～28cm,优势体重组为200～300g;7、8月份优势叉长组为24～26cm,优势体重组为100～200g。蓝圆鲹优势叉长组为20～21cm。2000年7、8月份鲐鱼优势叉长组为24～26cm。1999年鲐鱼叉长组成基本呈正态分布,2000年鲐鱼叉长组成明显存在两个峰值。2000年相同叉长的鲐鱼体重要略低于1999年,认为跟1999年、2000年海洋环境因子变化有关。从相关系数来看,2000年的曲线更贴近实际情况。并认为5月份北上参加产卵洄游的鲐鱼群体、其性腺已开始发育成熟,并沿途产卵。

A Preliminary Study on Biology of Chub Mackerel Scomber japonicus and Round Scad Decapterus maruadsi in the Southern East China Sea

This paper analyzed the fork length, body weight and sexual maturity of chub mackerel (Scomber japonicus ) and round scad ( Decapterus maruadsi) caught in the southern East China Sea. Field measurements indicated that in 1999 the dominant fork length and body weight of chub marckerel were 26-28cm and 200-300g respectively in May, and 24-26 cm and 100-200g respectively in July and August; the dominant fork length of round scad was 20-21 cm. In July and August 2000, the dominant fork length of chub mackerel was 24-26 cm. The fork length composition of chub mackerel in 1999 was almost normally distributed, but it obviously showed two peaks in 2000. Average individual weight of chub mackerel of the same length group is slightly lower in 2000 than that in 1999. It is suggested that changes of sea environment in 1999 and 2000 would be the possible reason for that. According to the correlation between the fork length and body weight of chub mackerel, the curve of 2000 is much closer to the real case. It is indicated that the sexual gland of chub mackerel began to get mature when taking spawning migration in May and continued to spawn while migration.