Monitoring the Aspects of Reproductive Ecology of Chrysichthys auratus in the Volta Lake, Ghana

Abstract

The study was conducted in 2018, on the Chrysichthys auratus in the Volta Lake, due to its socio-economic importance to the many and varied dependent fishermen, fish processors and fish traders. The objective was to determine the reproductive strategy to facilitate sustainable management of the fish stocks. A total of 452 fish samples collected on monthly basis were measured, weighed and dissected for determination of, sexual maturity, sex ratio, gonadosomatic index GSI, hepasomatic index HSI, condition factor k, visceral fat index VFI, and monthly stomach fullness in relation to sexual maturity. According to the length at first maturity determined, 89% of the female fish caught, fell below that critical length, suggesting growth overfishing, attributed to size and sex selective tendencies of bamboo pipe fishing. During gonad development, the correlation of the GSI to the HSI and the VFI was inverse and insignificant but in the post gonad development phase it switched to a positive and insignificant relationship. The point of switch, in September, was synonymous with spawning and indicative of the spawning period. It was concluded that the reproductive strategy was to time the spawning process, in September, to coincide with the upwelling phenomenon (June – September), associated with fish food abundance, thereby enhancing the survival of the offspring. A seasonal ban on fishing and a total ban on bamboo pipe fishing were recommended.