CHANGES IN THE ABUNDANCE AND MORTALITY RATE OF TIGERFISH IN THE EASTERN BASIN OF LAKE KARIBA

Abstract

Tigerfish populations increased in the eastern basin of Lake Kariba following the successful invasion of the pelagic clupeid Limmothrissa miodon. Strong year-classes persisted for several years but the number of young tigerfish declined, a phenomenon which cannot be accounted for. The influence of these year classes on different fisheries was demonstrated. The mortality rate of the younger fish was related to the rate at which their numbers were changing with mortality rates being highest when numbers were declining most rapidly. Concern about the future of this fish was expressed because of increased fishing in its main breeding area.