First record of Labeo capensis (Smith, 1841) in the Crocodile River (West) system: another successful non-native freshwater fish introduction in South Africa

Abstract

South Africa is one of six global fish invasion hotspots and as a result, non-native fishes are common components of the fish assemblages in all of the major river systems. The rate of establishment for introduced fish into South African rivers is high (79%) and the vector responsible for the highest establishment rate is interbasin transfer schemes with 80%. Introductions of non-native fish into river systems can negatively affect native fish species through hybridisation, competition for food sources and predation, and the introduction of associated parasites and diseases. The aims of the current study were to provide evidence of the introduction of Labeo capensis into the Crocodile River (West) system, using morphological and molecular techniques, and to record the fish health and gonadosomatic index to determine the invasive status of L. capensis. From the fish health assessment index and gonadosomatic index of L. capensis collected from Olifantsnek Dam, it can be concluded that L. capensis is a healthy reproducing population. Because this fish species can survive and reproduce in newly colonised river systems, it has the potential to compete with the native fish species for food and habitat, but can also hybridise with native Labeo species.

Keywords: fish health, genetic barcode, gonadosomatic index, invasion hotspots, translocation