Effects of fish restoration practices on amphibians in
yellowstone national park, wyoming
Hilary G. Billman,* Sophie St-Hilaire, and Charles R. Peterson, Department of Biological
Sciences, Idaho State University, Pocatello, Idaho 83209 firstname.lastname@example.org
Todd M. Koel and Jeffrey L. Arnold, Yellowstone Center for Resources, Fisheries and Aquatic
Sciences Section, P.O. Box 168, Yellowstone National Park, Wyoming 82190 Todd_Koel@nps.
Carter G. Kruse, Turner Enterprises, Inc., 1123 Research Drive, Bozeman, Montana 59718 carter.
Throughout the Western United States, fisheries managers are attempting to restore native
cutthroat trout (Onchorynchus clarkii) populations by removing nonnative fish species. A
new formulation of the EPA approved piscicide rotenone (CFT Legumine) is increasingly
being used as a method to accomplish this removal. Because fish restoration projects bring
about an abrupt change to aquatic environments, it is important to consider their immediate
and long-term effects on non-target species, such as amphibians. We assessed the effects of
fish removal on amphibians in Yellowstone National Park (YNP) by investigating the toxicity
of rotenone to and the long-term impacts of removing fish on local amphibian populations.
CFT Legumine (5% rotenone) was applied to High Lake in YNP (2006) to remove stocked
Yellowstone cutthroat trout (O. c. bouvieri). To determine toxicity, amphibian surveys were
conducted immediately prior to the treatment to obtain pre-treatment tadpole population
estimates. Post-treatment surveys were conducted both immediately, for assessing treatment-
related mortality (during and after application), and 1, 2, and 3 years following to obtain
tadpole abundance estimates in the years after application and to address the long-term effects
of fish removal and reintroduction. The results of the toxicity trials revealed that in the 24 hrs
following application, rotenone was lethal to gill-breathing amphibian tadpoles and non-
lethal to non-gill breathing metamorphs, juveniles, and adults. In the years following, tadpole
repopulation occurred at levels above the pre-treatment abundance estimate, though both
tadpole abundance and distribution appeared correlated with fish presence.