Aspects of reproductive biology of big eye grunt Brachydeuterus auritus (Valenciennes, 1832)

Aspects of reproductive biology of big eye grunt Brachydeuterus auritus off Lagos coast, Nigeria were investigated and focussed on sex ratio, gonadosomatic index, stages of gonadal development and fecundity. A total of 450 fish with body length of 11.7 - 19.3 cm (total length) and body weight of 12.4 - 110.5g were used for this study. The sex ratio of B. auritus was 1: 1.11 (male to female). The females were more than the males. However, there was no significant difference (p > 0.05) in sex ratio from the expected 1:1 distribution. Gonadosomatic index ranged from 0.18 - 12.73%. The mean gonadosomatic index was 3.96 ± 0.19%. High gonadosomatic indices were observed in July, August and September which indicated the spawning period and falls within the wet season. Quiescent, maturing and mature ovarian and testicular stages of gonadal development were observed in all samples of B. auritus collected for this study. Fecundity ranged from 12,503 - 74, 045 eggs with a mean of 32, 344 ± 1,889 eggs. This suggested that B. auritus is a low fecund fish. Fecundity-length and fecundity-weight relationships showed positive correlations. The Fecundity-length and fecundity-weight relationships were determined by regression analysis with the regression equation Log F = 1.8985 + 2.2706 Log L (r = 0.5083) for fecundity-length relationship and Log F = 4.0292 + 0.2657 Log W (r = 0.3090) for fecundity-weight relationship. Fecundity was more related to length than to weight. This information is relevant for fisheries recruitment and population dynamics as well as breeding programmes in aquaculture of B. auritus. (Fatimat Adenike Adebiyi. Aspects of reproductive biology of big eye grunt Brachydeuterus auritus Valenciennes, 1832) . Nature and Science 2012;10(2):19-24). (ISSN: 1545-0740). http://www.sciencepub.net. 3