春季钓鱼岛海域竹鱼产卵群体生物学特征的研究

利用2005年3月在钓鱼岛海域捕获的竹鱼产卵群体样品测定数据,对其主要生物学特征、主要产卵期和繁殖力特征进行了研究。结果表明,钓鱼岛海域是春季东海南部竹鱼的主要产卵场,主要产卵期为3月中下旬。根据叉长和体重的频率分布图,可以看出该产卵群体主要有3个叉长优势组,其中以200～220mm和230～240mm叉长组为主,260～270mm叉长组个体极少;体重的组成特征与叉长组成基本一致。由于所取样品处于产卵后期,因此条件生长因子相对较小。个体绝对生殖力在12264～37629粒/尾,个体平均绝对生殖力为27844±10179粒/尾;单位长度生殖力范围为50～157粒/mm,平均值为121±42粒/mm;单位纯体重生殖力为82～238粒/g,平均值为202±68粒/g。

Study on the biological characteristics of jack mackerel Trachurus japonicus spawning stock in Diaoyu Islands waters in spring

The main biological characteristics, the main spawning period and fecundity characteristics of jack mackerel spawning stock were studied based on the sample data obtained in Diaoyu Islands waters in March, 2005. The results showed that the Diaoyu Islands waters was the main jack mackerel spawning grounds in the southern East China Sea in spring, and the main spawning period was in the middle and late March. According to the fork length and weight frequency distribution, the main spawning stock had three dominant folk length groups, 200~220mm, 230~240mm, and few individuals of 260~270mm. The composition characteristics of body weight were consistent with the fork length composition. Since the samples were taken in the late spawning period, the conditional growth factor was relatively small. The absolute individual fecundity was 12 264±37 629 grain and the mean individual absolute fecundity was 27 844±10 179 grain. The fecundity per unit length was in the range of 50~157 grain/mm, at an average of 121±42 grain/mm. The fecundity per unit net weight was in the range of 82~238 grain/g,at an average of 202±68 grain/g.