ASSESSMENT OF THE FISHERY OF A STUNTED POPULATION OF THE CICHLID, SAROTHERODON-MELANOTHERON (RUPPEL), IN A CLOSED LAGOON IN GHANA

This paper examines the status of the tilapia fishery in Fosu Lagoon a t Cape Coast, in the Central Region of Ghana (5-degrees-07' N, 1-degre es-16' W). The blackchin tilapia, Sarotherodon melanotheron (Ruppel), constitutes about 90 % by weight of the total fish catch, and the annu al yield of 452-664 kg/ha is appreciably higher than those reported fo r other tropical lagoons. Variations in the CPUE (0.30-0.96 kg/man-h) were related to fluctuations in the water level of the lagoon. Using t he ELEFAN method, estimates of the growth and mortality parameters, ba sed on length-frequency data were: Loo = 16.1 cm TL, K = 0.82/yr, Z = 4.95/yr, M = 1.90/yr and F = 3.05/yr. The growth estimates and the mat urity-length ratio suggest that the population is stunted. The mean le ngth at first capture (Lc50) was estimated to be 6.2 cm TL. Although t he present rate of exploitation (E = 0.62) appears high, an analysis o f the relative yield-per-recruit (Y'/R) and high recruitment shows tha t this exploitation rate can be maintained by the lagoon population. R ecruitment occurs throughout the year with two peaks, and this probabl y ensures the sustenance of the high yield.