1Kenya Marine & Fisheries Research Institute, P.O. Box 1881, Kisumu, Kenya
2Lake Victoria Fisheries Organisation, P.O. Box 1625, Jinja, Uganda

The effect of overfishing and other Environmental factors on the life-history styles of Nile tilapia, Oreochromis niloticus (L.) in the Nyanza Gulf of Lake Victoria, Kenya

Breeding growth, mortality and feeding ecology data were collected from 1998 to 2000. The data were compared to earlier results obtained in Lake Victoria in order to establish the current life history tactics exhibited by O. niloticus in the Nyanza Gulf. Observations on the reproductive effort and related environmental factors point to a fish species under stress. It is observed that the changes in O. niloticus behaviour are not due to size selective predation, but due to size selective exploitation.

The influence of various environmental factors are discussed and evidence to show that O. niloticus in the Nyanza Gulf of L. Victoria allocate more energy to reproduction at the cost of somatic growth (i.e., increased turnover rate) are presented. It is concluded that O. niloticus in the Nyanza Gulf of Lake Victoria exhibits a "r" selected life history style in order to survive.