Unexpected survival of sharptooth catfish Clarias gariepinus (Burchell 1822) during acute rotenone toxicity trials will complicate management of invasions
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The sharptooth catfish Clarias gariepinus is an emerging global invader for which control strategies might include the use of piscicides such as rotenone. Experimental exposure demonstrated that C. gariepinus was less susceptible to rotenone than most other fish species, with unexpected survival observed at rotenone concentrations of 87.5 and 100 µg L−1. C. gariepinus were also observed exhibiting avoidance behaviour to rotenone treated water and were found to be capable of recovering from rotenone exposure. As such, effective eradication might not be attainable even at a dose exceeding 100 µg L−1 with exposures of longer than 24 h. This exposure scenario may pose an unacceptable risk to non-target fauna and highlights the difficulty associated with managing current and future invasions.
KeywordsAcute toxicity Behaviour effects Biodiversity restoration Global invader Invasions Rotenone
The authors wish to acknowledge the technical support provided by Kevin Shaw, Francois Jooste, Sonja Erasmus and Thaaqirah Joseph during the execution of the experimental work. Stellenbosch University Division of Aquaculture is thanked for the use of equipment. The National Research Foundation (NRF) of South Africa (UID: 77444) and Department of Science and Technology (DST)/NRF Centre for Invasion Biology, Water Research Commission (Project K5/2261; K5/2638) are thanked for their support. Ethical clearance was obtained prior to commencement of the study from the animal ethics committee of the South African Institute for Aquatic Biodiversity (Reference 2014/01).
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