Dynamics of Inter-Population Reproductive Pattern in Butter Catfish, Ompok Bimaculatus (Bloch, 1794) from Different Rivers in India.

Abstract

This study demonstrates the comparative pattern of reproductive parameters viz. sex ratio, size at first gonadal maturity, gonadosomatic index (GSI), fecundity, egg dimension of O. bimaculatus analyzed from 13 different rivers during 2011–2013. It was observed that females start to mature earlier than males and mean size at first maturity in male and female varied considerably between the different populations. The reproductive period of fish were extended from April - August while in Southern rivers it was extended from March to July. The results indicated three types of reproductive patterns of O. bimaculatus in terms of age at first sexual maturity and absolute fecundity and distinct variation was observed across different rivers. The meanabsolute fecundity varied significantly between the rivers and was grouped in to three categories: (i) high absolute fecundity (ii) medium fecundity and (iii) low fecundity. The results indicated significant and positive correlation between absolute fecundity and total length, body weight and ovary weight in all the rivers (P<0.05). The oocyte distribution during the maturity season was consistent within the ovary but more fluctuations were observed within different population. This study provides quantitative account in to the comparative reproductive potential and inter-population reproductive strategies for the first time.