Growth And Mortality Parameters Of Sarotherodon Melanotheron (Teleostei: Cichlidae) In Two Brackishwater Systems In Ghana
Abstract
Growth and mortality parameters of the black-chinned tilapia, Sarotherodon melanotheron melanotheron populations in Benya Lagoon and Kakum River Estuary (Ghana) were detennined by analysis of length-frequency data using the ELEFAN computer method. The study was aimed at obtaining requisite information for the assessment and management of the stocks. The growth
parameters indicated a faster growth in the estuarine population (K=1.25/year) than the lagoon population (K=0.61/year) but the former attained a smaller asymptotic length (L∞ =10.0 cm SL)
than the latter (16.4 cm SL). Estimated life-span for the estuarine and lagoon populations were 2.4 and 4.7 years, respectively. Both populations were, however, considered stunted when these
parameters are compared with those of populations with larger maximum sizes. Stunting in the two populations was further implied by their low maturity-length ratios (< 0.50), and maturity
ages of 3 months in the estuary and 5 months in the lagoon. The total mortality rate (Z) was higher in the estuarine population (5.17/year) compared with the lagoon population (3.49/year),
and the higher mortality rate in the estuarine fish might possibly be compensated for by its higher recruitment rate.
