Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 39

Abstract

Part 1: The nature of the barriers separating the Lake Malawi and Zambezi fish faunas: The nature of the barrier separating the ‘Lake Malawi’ from the ‘Lower Zambezi’ fish faunas was investigated by electrofishing the 145 km stretch of the Shire River surrounding the Murchison cataracts. The study shows that the lowermost element of the cataracts, the Kapachira Falls, is an absolute physical barrier to upstream movement of ‘Lower Zambezi’ species. The barrier to downstream movement by ‘Lake Malawi’ species is largely ecological and has two components, the fluviatile nature of the Upper and Middle Shire and especially the torrential nature of the cataracts, which are unsuitable for lacustrine species, and competition with the ‘Lower Zambezi’ fauna of the Lower Shire by the few species which succeed in negotiating the cataracts.Part 2: An annotated checklist of the fish fauna of the River Shire south of Kapachira Falls, Malawi: The Shire River drains Lake Malawi and is a major tributary of the Lower Zambezi River. Sixty-one species of fish have been recorded in the lower reaches which are separated from the lower Shire basin by the Kapachira Falls and from the ‘East Coast River’ fauna present in the Upper Ruo River by the Zoa Falls. The fauna is essentially similar to that of the Lower Zambezi, although some Lake Malawi endemics occur sporadically in the upper part of the flood plain.Rhodes University Libraries (Digitisation