Effects of Fish Restoration Practices on Amphibians in Yellowstone National Park, Wyoming

Scientific Disciplines
Biological Sciences - Aquatic
cutthroat trout
yellowstone cutthroat trout
Yellowstone national park
Yellowstone National Park Wyoming
Charles R Peterson Department Biological Sciences Idaho State University Pocatello Idaho
Jeffrey L Arnold Yellowstone Center Resources Fisheries Aquatic Sciences
Yellowstone Center for Resources, Fisheries and Aquatic Sciences Section
Idaho State University
Turner Enterprises Inc.
fish removal
tadpole abundance
longterm effects
fish restoration
amphibians yellowstone
cft legumine
effects fish removal
amphibians yellowstone national
amphibians yellowstone national park
Volume 16, No. 4

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 billhila@isu.edu
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.