Increased backcrossing has reduced the usefulness of morphological and allozyme data for identifying Oreochromis niloticus, O. mossambicus (Teleostei: Cichlidae) and their hybrids in the Pafuri reach of the Luvuvhu River in the Kruger National Park, South Africa

Abstract

Alien Oreochromis niloticus, indigenous O. mossambicus and individuals that appeared hybrid-like were sampled from the Luvuvhu River, a tributary of the Limpopo, near Pafuri in the Kruger National Park. Starch gel electrophoresis of muscle tissues and the resolution of protein loci using specific histochemical techniques identified the pure species as well as verifying the presence of hybrids. There was a reduction in the numbers of O. niloticus and hybrids in 2002, compared to those reported previously. There were overlaps in the various morphological characteristics that were studied, so these were not useful for identification of taxa. However, recent analyses indicate that allozyme data are no longer useful for differentiating between the current backcrossed individuals.