Sex ratio, gonadal development and fecundity of the grunt, Pomadasys jubelini (Cuvier, 1830) in the new Calabar-Bonny River, Nigeria

Abstract

The sex ratio, gonadosomatic index, stages of gonadal development and fecundity of the grunt, Pomadasys jubelini in the New Calabar-Bonny River were investigated. P. jubelini had a sex ratio of 1: 2.1 (male to female). Gonadosomatic index ranged from 0.33 to 7.29% with a mean of 2.89+0.08%. High gonadosomatic indices were recorded from September to October, which indicates the production period of the fish. Two stages; maturing and mature were observed for male fish while quiescent, maturing and mature were observed for female fish. Fecundity ranged from 9,085 to 37,926 eggs and a mean of 25,852+432 eggs. This is an indication that P. jubelini has low fecundity. Fecundity-body weight and fecundity-body length were positively correlated. Fecundity-weight relationship was Log F=0.1243+2.74 Log W (r=0.950). Fecundity-length relationship was Log F=0.0247 + Log 1.779 log L=(r=0.114), Fecundity was more related to weight than length. P. jubelini begins spawning during the rainy season in marine and estuarine environments. During this period large number of fingerlings and juveniles are in abundance. The results of this study will assist in increasing the knowledge of the reproductive biology of P. jubelini which is relevant in aquaculture development of the species.

Keywords: Fecundity, gonadal development, gonadosomatic index, New Calabar-Bonny River, Pomadasys jubelini