Lake Kariba, Zimbabwe
Fish poplLlation changes in the Sanyati Basin, Lake Kariba, Zimbabwe D.H.S. Kenmuir Lake Kariba Fisheries Research Institute, Department of National Parks and Wildlife Management, Zimbabwe Large-fish population changes in the Sanyati Basin of Lake Kariba This paper considers the major natural large-fish population between 1960 and 1975 are evaluated and discussed. The early changes in the Sanyati Basin of Lake Kariba (Figure 1) between lake population following closure of the dam wall in 1958 was similar to the pre-impoundment riverine population with Labeo 1960 and 1975. With the exception of Jackson (1960) who dealt spp., Distichodus spp., Clarias gariepinus and two characid with the immediate effect of darn closure on the river fish species dominating gill-net catches. Exceptions were mormyrids, population, nothing empirical has yet been published on this scarce in the new lake although abundant in the river, and Oreochromis mortimeri, scarce in the river but expanding rapidly aspect of the biology of Lake Kariba fish, despite the lake be in the lake. Productivity in the new lake in terms of ichthyomass ing in existence now for 25 years_ The subject has, however, relative to later years was high. In later years following closure been discussed partially and in general terms by van der Lingen several of the early abundant mostly potamodromous species declined rapidly (C. gariepinus, Labeo spp., Distichodus spp.,) and (1973), Bowmaker, Jackson & Jubb (1978) and Kenmuir (1978, by 1975 they were unimportant. Mormyrids, cichlids and two 1983), while unpublished data on some aspects are those of silurid species increased significantly in catches as did the Donnelly (1971), and the report ofKenmuir (1977), from which characin, Hydrocynus vittatus; the latter as a result of the expan sion of the freshwater sardine population, from 1970.
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