This study is dedicated to the memory of Ben Chanda who suddenly passed away while we were working on it. Ben Chanda worked for the African Wildlife Foundation and before that for the Fisheries Department of Zambia.
The fishery of the Bangweulu swamps, in Luapula Province, Northern Zambia (Figure 1), is an artisanal small-scale multi-gear, multispecies fishery. Eighty-three species representing 13 taxonomic families have been recorded from the area (Evans, 1978) most of which are caught and utilized. The general impression with the local administration is that the fish stocks are heavily fished. Presently fish stocks are considered threatened by high fishing pressure from both the large numbers of permanent residents in the swamps as well as from the seasonally migrating fishermen coming from surrounding areas. Already for a long time fears have been expressed that the fishery of the Bangweulu system has undergone alarming changes indicated by a decrease in the mean size of fish caught and a general decline in catch per unit effort (Evans, 1978). Total yields however, although fluctuating, show an increasing trend. Fishermen are believed to contribute to these changes by an intensified utilization of small meshed gillnets, seining, weirs, as well as kutumpula fishing - a technique which drives the fish into surrounding gillnets by beating into the water (Mortimer, 1965). There is a need for evaluating these changes in the fishery and to establish whether they are indications of possible overfishing, inappropriate (and illegal) fishing practices, or natural factors.
This case study will present and discuss the main results from a length-based stock assessment survey carried out in 1994-1995 (Kolding, Ticheler and Chanda, 1996a, 1996b). The survey was made to establish growth parameters, gear selectivity, individual exploitation rates, and overall exploitation pattern in the multispecies swamp fishery. We conclude that the observed changes are not alarming. On the contrary: we find that the fishery is remarkably adaptable to the natural circumstances; that the exploitation is heavy, but with no evidence of gross overexploitation in general, at the most on some of the larger species; and that the current exploitation pattern is to a large degree unselective and thus in principle ecosystem conserving.