The feeding ecology of two Nile crocodile populations in the Zambezi Valley

Abstract

The objective of this study was to assess the impact of crocodiles (Crocodylus niloticus) on the fish populations of Lake Kariba as compared to the one of fisheries. The lake supports a successful crocodile management scheme based on egg collection for rearing and release of three-year- old animals, which is operated by the Department of National Parks and Wildlife Management. The fishery has expanded since independence in 1980 (Murphree et al. 1989) and there is pressure to open up areas that were previously closed to fishing. Conflicts exist between fishermen and crocodiles (Chimbuya and Hutton 1988) with many of the problems centering around competition for the resource (i.e. fish and space for fishing or for nesting activity). This study is the first to estimate fish consumption by crocodiles in a natural ecosystem and it is hoped that it might be representative of other places in Africa. Previous studies were combinations of data from several localities (Cott 1961) or from populations of a cool water reservoir: Ngezi reservoir, Zimbabwe (Hutton 1984) or of a lake surrounded by desertic zones: Lake Turkana, Kenya (Graham 1968).