SOME OBSERVATIONS ON FISH MIGRATIONS IN CAPRIVI, NAMIBIA

Abstract

Longitudinal and lateral migrations of freshwater fish were observed in 63 (83%) of the fish of the Upper Zambezi in the Caprivi region, Namibia. The results of 20 surveys showed that longitudinal upstream migrations were undertaken by most small cyprinids, mormyrids, distichodontids, characids, schilbeids, clariids and mochokids but by only a few of the larger cichlids. Similarly, lateral migrations out of permanent waters were common for young mormyrids, some smaller barbs, small characids, Schilbe, a few mochokids, cyprinodonts, most cichlid species and both anabantids. Breeding migrations were observed only in Clariasspp and some barbs. All other fish movements seem to be connected with invasions into newly inundated habitat, escape from desiccation, movement back to permanent water or else an upstream or downstream movement away from areas with temporary high densities in an effort to escape predation or seek new feeding ground. An unexpected large number offish species (34) were collected in isolated pools at the edge of the floodplain after the floods had receded.