Reproductive potential of <i>Sarotherodon galilaeus</i> (Linnaeus: 1758) in a tropical coastal estuary

Abstract

The study aimed to investigate some aspect of reproductive potential of Sarotherodon galilaeus in tropical coastal estuary, Nigeria. Sex ratio, absolute and relative fecundity, GSI, egg diameter, gonadal stage and length-at-first maturity were assessed monthly over a period of six months. The overall sex ratio was in 1:2.83(Female: Male) and was significantly (χ2 = 28.27: p< 0.05) different from the hypothesized sex ratio of 1:1. Fecundity mean value estimated of the fish population was 1079.14±64.29 egg/fish. Ganadosomatic index indicated a breeding period between February and July. A linear positive relationship was observed between egg diameter and ovary weight ED = 0.918OW^3.0214 (r² = 0.9340). Maturity stage revealed that 36.47% and 45.19% of both sex (M: F) were in their reproductive stages especially between the month of April to July. High L₅₀ value estimated for both sex indicated prolonged reproduction process of the fish. Reproductive indices analysed indicated that the population has a potential to thrive in the estuary, but intense fishing pressure should be avoided to prevent its extinction in the fishery.