An assessment of Cichild fishery of Bontanga reservoir, Northern Ghana

Abstract

The stock parameters of three cichilds, Oreochromis niloticus, Sarotherodon galilaeus and Tilapia zilli, which dominated the catches of artisanal gill net fishery in Bontanga reservoir were studied, Estimates of the growth and mortality parameters of the stocks enabled application of Beverton and Holt Relative yield-per-recruit (Y’/R) models to estimate the maximum sustainable yield-per-recruit (MSY/R), corresponding fishing effort (FMSY/R), and the exploitation rate at which 50% of the biomass-per recruit (F0.5) were exploited. On annual basis, growth of the cichlids were describe by the von Bertalanffy growth equation: O. niloticus: L1 = 23.63(1-exp (0.58)1 + 0.10)], S. galilaecus: L1 = 36.73[1-exp (0.26) (1 + 0.10)] and T. zillii: L1 = 21.53(1 – exp (0.60 (1 + 0.10)]. The asymptotic length (Loo) range of 21.6-36.9 cm and the maturity length ratio (Lm/Loo) of 0.19-0.39, which was less than 0.7, suggested that the fishes were stunted. The mean length at first capture of O. alioticus was 9.1 SL cm and for S. galilaeus and T.zillii were 7.SL cam and 4.5 SL cm. respectively.