Alien fishes: Do we know enough for effective management?
Olaf L.F. Weyl1, Bruce R Ellender1, Ryan J Wasserman1, Sean Marr1, Philip Ivey4, Darragh J. Woodford2, Mhairi E. Alexander3, Tsungai A. Zengeya4, Martine Jordaan5, N Dean Impson5
1Center for Invasion Biology, South African Institute for Aquatic Biodiversity
2Center for Invasion Biology, University of the Witwatersrand
3University of the West of Scotland
4South African National Biodiversity Institute, Pretoria National Botanical Gardens
Fifty-five fish species have been introduced into novel environments in South Africa. While pathways for initial introductions are fairly well understood, there is a paucity of information on subsequent spread, establishment and impact for many of these species. Effective management of these invasions requires not only current knowledge of invasion status and invasion risk so that species or ecosystems can be prioritised for intervention. This paper will provide: (1) a review of drivers, pathways and the invasion status of introduced fishes; (2) a summary of impacts and utility
(e.g., potential for management conflicts) and (3) a measure of invasiveness derived from an adaptation of the Freshwater Fish Invasiveness Scoring Kit (FISK) to South African conditions. These data are then used to prioritise species for management intervention. The contribution of this paper to the National Status Report on invasive species is evaluation of management priorities based on an up to date synopsis of the current status and risk of spread for alien and extralimital fishes in South Africa.