バングラデシュ水系のHilsa ilishaの2型の産卵と孕卵数〔英文〕

概要

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The study of spawning, fecundity and sex ratio of two types (A and B) of Hilsa ilisha showed that they had different breeding seasons, i.e., type A from July to October and type B from January to March. Spawning season was determined from gonadosomatic indexes and the peak spawning occurred in September for A and February for B type. Fecundity was found to range from 660 to 1547 thousand for fish between 342 to 520 mm of type A and 399 to 670 thousand for fish between 260 to 470 mm in total length of type B, and observed to be related to total length, body weight, gonad weight and age of the fish. Regarding the sex ratio of type A, the females were preponderant in the months of October and December whereas the males were preponderant in June, but in the case of type B, it was observed to be 1:1.
日本水産學會の論文