A survey of the fish fauna of Transkei estuaries. Part 1. The Kei River estuary

During the period of survey the 8 km long Kei estuary was subjected to periodic floods which reduced salinities to 0%o and decreased light penetration to a few centimetres. Species composition, and temporal and spatial abundance were determined for fish samples collected by means of gill nets. Twenty-six species of fish were caught with Mugil cephalus, Liza tricuspidens and Argyrosomus hololepidotus predominating, in that order. The family Mugilidae comprised 67,8% of the numbers and 66,6% of the fish biomass caught. Definite seasonal patterns could not be determined for many of the fish although M. cephalus, L. richardsoni and A. hololepidotus were more abundant in summer. The effect of river flooding had unpredictable results on Mugilidae catches which either decreased or increased after floods while catches of P. commersonii and A. hololepidotus usually increased. Largest catches were made in the middle reaches although species diversity was greatest in the lower reaches of the estuary.