Reproductive biology of Bagrus docmak in the Victoria Nile, Uganda

Abstract

Aspects of the reproductive biology of Bagrus docmak in the Victoria Nile were investigated between November 2005 and October 2006. Macroscopic and histological analysis of the gonads confirmed it as an asynchronous batch spawner which spawns throughout the year with bimodal spawning peaks coinciding with rainfall seasons. The first spawning peak occurred from March to May, the second from September to November. The sex ratio did not significantly deviate from 1:1. Length at sexual maturity was 33.6 cm and 31.6 cm fork length (FL) for females and males, respectively. Batch fecundity ranged from 1 000 eggs in 34 cm FL fish to 43 000 eggs in 79 cm FL fish, and correlated linearly with FL (r = 0.72) and body weight (r = 0.79). Mean relative batch fecundity was 6 eggs g^–1 (SE 2). These results could guide research into the possibility of artificially inducing the fish to spawn, and its subsequent culture.

Keywords: fecundity, induced spawning, length at sexual maturity, oocyte maturation, reproductive seasonality

African Journal of Aquatic Science 2013, 38(3): 263–271