An assessment of a proposal to eradicate non-native fish from priority rivers in the Cape Floristic Region, South Africa

Abstract

Non-native fish are considered the most important threat to the survival of the indigenous freshwater fishes in the Cape Floristic Region (CFR). A pilot project to evaluate the use of the piscicide rotenone to eradicate non-native fish from selected reaches in four rivers has been proposed by CapeNature, the conservation authority of the Western Cape province, South Africa. Each river has unique characteristics and challenges to achieving the eradication of non-native fish and the restoration of its indigenous fish assemblage. The proposal is described and the management methods available for reducing the impact of non-native fish on indigenous species are discussed. An environmental impact assessment (EIA) concluded that the project was justified and necessary, the choice of rivers sound, and supported the use of piscicides. The need for the project, the selection of sites and the findings of the EIA are discussed. It is expected that the project will be successful while having minimal impact on other aquatic fauna. The successful completion of the pilot project could help establish methods to eradicate non-native fish from critical biodiversity areas in South Africa. Such projects must, however, be part of a comprehensive conservation management plan to be implemented by conservation agencies in the CFR.