Distribution and seasonal movement of pelagic fish in southern Lake Tanganyika

Abstract

The distribution and seasonal movement of two planktivorous clupeids, Stolothrissa tanganicae and Limnothrissa miodon, and one predatory centropomid fish, Lates stappersi in the southern end (Zambian waters) of Lake Tanganyika were studied using purse seine fishery statistics and species ratio data collected between 1984 and 1992. L. stappersi is the most abundant offshore among the three species and moves northwards into waters of other countries during the dry season. L. miodon occupies the inshore regions of the lake, and does not appear to move offshore beyond Zambian waters. S. tanganicae is more dominant in the offshore waters than L. miodon and there is a strong possibility that it moves out of the Zambian waters. The presence or absence of the predator, L. stappersi, seems to affect the distribution of the two prey clupeid species. Species-based management of either clupeid, which are captured together, may not be meaningful but an assumption of close-equivalent population in the wet season may be useful in implementing seasonal regulations. International management policies may have to be introduced for L. stappersi.