Freshwater fish of the Wilderness National Park

Abstract

The study aimed to determine the distribution and relative abundance of freshwater fish in the Wilderness National Park. Fish assemblages in the Touw and Duiwe rivers were sampled in 1997 and 1998, with a total of 327 fish from nine species recorded. Indigenous species included two freshwater species (Pseudobarbus afer, Sandelia capensis), two catadromous species (Anguilla mossambicus, Myxus capensis), and two estuarine species (Monodactylusfalciformis, Caffrogobius multifasciatus). Three of the nine recorded species were alien (Micropterus dolomieu, Micropterus salmoides, Gambusia affinis), with the Micropterus spp., in particular, likely to have a substantial negative influence on indigenous species. A further one indigenous species, two translocated indigenous species, and five estuarine species could potentially be recorded in these rivers. River catchment management actions to restore perennial flow to the Duiwe River, to prevent the attenuation of floods, and to prevent further establishment and spread of alien and translocated biota are required to conserve indigenous fish assemblages.

Keywords

• freshwater fish, diversity, alien, Wilderness National Park.