Population Dynamics of the African River Prawn, Macrobrachium vollenhovenii, in Dawhenya Impoundment

Studies were conducted on the growth and mortality parameters, recruitment pattern, probability of capture, yield-per recruit, and present rate of exploitation of the African river prawn, Macrobrachium vollenhovenii from Dawhenya impoundment, Ghana. Estimation of the von Bertalanffy growth parameters gave; L-infinity = 14.2 cm, K = 1.0 yr(-1), and t(o) = -0.195 yr(-1) with the growth performance index, Phi' of 2.303. From the linearised length-converted catch curve, total mortality, Z was 5.36 yr(-1). Natural mortality, M calculated from Pauly's empirical formula was 2.20 yr(-1) and fishing mortality, F calculated from Z - M was 3.16 yr(-1). From the mortality estimations, the present rate of exploitation, E calculated from F/Z was 0.59 indicating that, the species is on the verge of being over-exploited in the impoundment. Using the estimated value of the growth coefficient, K, the longevity was found to be about 3 yrs. Estimations from the probability of capture routines gave the length-at-first capture, L-c as 3.07 cm while the size distribution of the catches suggest two recruitment pulses in a year. It is therefore recommended that, the property right-based system for fisheries management should be implemented so that fishermen can cooperate in the management of the Macrobrachium fishery.