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Providing evidence to improve practice

Individual study: Elimination of introduced fish resulted in increased amphibian species diversity and reproductive success in ponds in Illinois

Published source details

Walston L.J. & Mullin S.J. (2007) Responses of a pond-breeding amphibian community to the experimental removal of predatory fish. American Midland Naturalist, 157, 63-73


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Remove or control fish using rotenone Amphibian Conservation

A continuation of a replicated, before-and-after, site comparison study (Mullin, Towey & Szafoni 2004, Towey 2007) in 2001–2004 (Walston & Mullin 2007) found that amphibian diversity and smallmouth salamander recruitment increased significantly after fish elimination using rotenone. Species relative abundance increased from 0.2 to 0.7 and became similar to that in historically fishless ponds (0.5–0.6). Small-mouth salamanders became the most abundant species in both treatment (41%) and fishless ponds (54%). American toad had been most abundant before fish removal (treatment: 91%; fishless: 67%). Although fish elimination did not result in increased salamander size at metamorphosis (42 vs 37 mm), it resulted in a significantly longer larval period (12% increase) and increased reproductive success (proportion of juveniles to breeding females: 0.3 vs 16.0). In fishless ponds larval period decreased 7% and recruitment was similar (0.2 vs 2.5). Numbers of juveniles increased significantly in treated (12 to 861) and fishless ponds (29 to 400). Amphibians were monitored before (2001) and after (2002–2004) treatment. One pond received a second application of rotenone to eliminate black bullhead catfish Ameiurus melas in January 2003.