Kenya Marine & Fisheries Research Institute, P.O. Box 1881, Kisumu, Kenya. E-mail: nyaundjo@hotmail.com

Growth and mortality of dagaa, Rastrineobola argentea (Pellegrin 1904) in Lake Victoria, Kenya

The seasonal recruitment of Rastrineobola argentea into the Nyanza Gulf, and its implications for sampling are briefly discussed. Monthly data both from landings and trawl surveys of R.argentea in Nyanza Gulf, Kenya, between 1997 and 2000 were analysed using the computer based ELEFAN 1 methods to obtain growth and mortality values. The estimated growth parameters are L¥ 65 mm SL and K 1.04 yr-1. Analysis of the length converted catch curve gave very high estimates of Z and F and consequently the exploitation rate, E, was estimated to be high. Total mortality (Z) was at 3.5-4.58 yr-1 A single annual recruitment peak (September/October) was observed. The size at first maturity of the endemic fish species was observed to be lower than past comparable studies, maybe as a reproductive strategy due to high fishing mortality. An attempt is made to identify feeding patterns and variations in the ecology of the Rastrineobola argentea in view of the management options discussed.