三门湾蓝点马鲛产卵群体结构和个体生殖力

Composition of spawning stock and individual fecundity of spanish mackerel in Sanmen Bay, Zhejiang

本文据1986年3—5月的调查资料研究了浙江三门湾蓝点马鲛生殖群体的叉长、体重、年龄组成、性比、性成熟系数、产卵类型、个体繁殖力及它们间的相互关系等,讨论了三门湾繁殖场蓝点马鲛的资源状况及资源保护措施。

The present paper deals with the results on the observations of the composition of the spawning stock and individual fecundity of spanish mackerel (Scomberomorus niphonius )in Sanmen Bay,Zhejiang,from March to May, 1986. The results are summarized as follows: 1. The principal composition of the spawning stock is the supplemental population in the Sanmen Bay. The age-9 individuals are dominant in the female fish,accounting for 65.48% of the total number of the female individuals. As to the male fish,the age-1 and age-2 individuals are dominant,ac- counting for 75.79% of the total number of the male individuals. 2. The individuals absolute brood amount varies between 127.8×10~3 and 3 183.6×10~3 eggs(average=891.30×10~3eggs). The individual relative brood amount R/L (anal length, in cm )varies between 2.61×10~3 and 35.53×10~3 eggs/cm (average=12.24×10~3 eggs/cm). The dynamical peculiarities of individual fecundity (R and R/L)increases with somatic weight , fork length and age. Among these three growth indices,the somatic weight is the most important ,and then the fork length and the age. The individual relative brood amount R/W (net somatic weight,in g )varies between 162.6 and 713.3 eggs/g (average=408.0 eggs/g) . It's change is not markedly related to fork length,somatic weight or age. 3. The spawning spansh mackerel releases eggs in separate batches. Each female fish releases eggs three times in a breeding season ,but only one time in the Sanmen Bay ,Zhejiang. The number of eggs in the third diameter group could accout for 19.64% of the total individual brood amount.