Re-introduction of endangered Berg-Breede whitefish to the upper Berg River in the Western Cape Province of South Africa

Summary

The Berg-Breede whitefish (Barbus andrewi), Endangered and reduced to less than 5% of its historical range in South Africa's Western Cape after invasive smallmouth bass devastated recruitment, had been considered extinct in the Berg River system by 2000, though a huge population (over 100,000 fish) persisted alongside multiple alien predators in the turbid Brandvlei Dam on the Breede system. When the new Berg River Dam finished filling in 2007, CapeNature saw an opportunity to re-establish the species in its former range, with the dam's Environmental Monitoring Committee approving the plan and stakeholders including angling clubs and the dam's managing authority helping catch and transport fish. Between October 2007 and February 2008, three stocking events moved 95-115 adult whitefish from Brandvlei Dam to the new reservoir, including fish caught during an angling tournament and briefly held in keep nets, some of which sustained handling injuries. A collaborative university monitoring program has conducted annual net surveys since the dam's closure, confirming 13 whitefish of 20-30 cm caught across 2008, 2009 and 2011, evidence of survival, but no juveniles have been detected, a concern given the species' slow growth. Difficulties included multiple established or emerging alien fish species in the catchment, insufficient agency capacity to mount a larger, better-timed stocking operation, and limited resources for regular surveys. The project rates itself partially successful, noting good use of stakeholder involvement and preliminary evidence the species is present in the dam, while recommending future stockings target dams within the species' natural range that are free of alien fish.