Wednesday, 2 January 2013

Managing invasive alien fish, Cedarberg

Invasion of the Rondegat River in the Cedarberg, Western Cape, by smallmouth bass Micropterus dolomieu has resulted in the extinction of several native fish species in the lower reaches of the river. In an attempt to rehabilitate aquatic environments for not only fish, but also amphibians and invertebrates, the piscicide rotenone is being implemented in this and other rivers by Cape Nature.

Clanwilliam yellowfish (Darragh Woodford, SAIAB)
Clanwilliam yellowfish (Olaf Weyl, SAIAB)
The fish team was led by Dr Olaf Weyl (SAIAB) and Bruce Ellender (Rhodes University), assisted by two MSc and nine Honours students. Dr Darrragh Woodford (SAIAB/Centre for Invasion Biology) was part of the invertebrate team.

    "Juvenile yellowfish were recorded in the first pool of the treatment area just three days after the operation, and two month later both yellowfish and redfin minnow Barbus callidus were recorded (the latter for the first time in probably 70 years)."

Read more about the preliminary surveys, the pilot project, and ongoing monitoring, in
Water Wheel Volume 11 No 6 November/December 2012.