房総海域におけるカタクチイワシの漁業生物学的研究-II

卵巣卵について

抄録

In order to observe the process of maturation and the number of eggs to be discharged during the spawning season, 175 specimens of female Japanese anchovy taken off BosoPeninsula during February through July 1966 and April through June 1967 were examined.
The maturity of Japanese anchovy could be classified by the diameter of large egg group and the number of modes in the distribution of diameter of eggs. The group of large eggs is called II-group.
The number of eggs in II-group estimated by gravimetric method was almost equal to the value estimated by volumetric method.
Frequency distribution of mean diameter of eggs has wider range at advanced stage than at earlier stage. The diameter of eggs in II-group increased with progress of maturation, although this was not referable to II'-group (medium-size egg group).
The diameter of eggs in II-group at spawning stage (D) was 1.05-1.60mm, which exce-eded the diameter of spawned eggs taken from the sea.
The number of eggs in II-group at Ba-C stage range from 600 to 20, 600 per individual female; mostly from 4, 000 to 17, 000.
The number of eggs (N) at ripening stage (C) was significantly correlated with body length of fish (L) at the coefficient of correlation, 0.774. The relationship between N and L can be expressed by the following formula: log N=0.155L+2.023
In the same stages (Bc-D), there was a trend that the heavier the ovaries weight the larger the number of eggs is.