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Toxicity of Rotenone and Antimycin to Silver Carp and Bighead Carp

Rach, J.J., Boogaard, M., and Kolar C., 2009, Toxicity of Rotenone and Antimycin to Silver Carp and Bighead Carp: North American Journal of Fisheries Management, v. 29, p. 388-395.

Abstract

The general public, natural resource managers, and government agencies have become increasingly concerned about the continued spread of silver carp Hypophthalmichthys molitrix and bighead carp H. nobilis in the Mississippi River basin and their potential spread into the Great Lakes. An integrated approach of chemical, biological, and physical measures is needed to reduce Asian carp populations in these waters. Rotenone and antimycin are the only general piscicides that are registered with the U.S. Environmental Protection Agency for controlling fish populations. Considerable information is available regarding the toxicity of these chemicals to numerous fish species. However, there is little available toxicity information indicating the potential for these chemicals to control Asian carp. In this study, Prenfish (5% rotenone) and antimycin (90% antimycin-A) toxicities to silver carp and bighead carp were assessed in acute toxicity and effective contact time tests. Each acute toxicity test consisted of fish being exposed to nine concentrations of a toxicant for 96 h in a static bath. In effective contact time tests, silver carp and bighead carp were exposed to the toxicants for 2, 4, 8, 12, or 24 h in a static bath. After each chemical exposure period, fish were transferred to recovery tanks containing freshwater for a 96-h mortality evaluation period. Tests were conducted at 12, 20, or 278C, and all concentrations were tested in triplicate. Effective contact time tests more accurately estimated expected field treatment mortality than did acute toxicity tests for exposures of 12 h or less. The acute toxicity trials for silver carp and bighead carp underestimated antimycin toxicity for 12-h exposures and overestimated Prenfish toxicity. In effective contact time trials, Prenfish-treated fish became immobilized early in the exposures and appeared moribund; however, many of these fish recovered in freshwater. Antimycin-treated fish that appeared unaffected by the chemical later died when placed in recovery tanks. Some native fish species survived antimycin or Prenfish exposures that killed Asian carp; however, the differences in sensitivity between these native fish species and Asian carp are not sufficient to permit selective removal of Asian carp from natural bodies of water. Prenfish and antimycin were both more toxic in warmer water than in cooler water, and both compounds would be toxic to Asian carp if applied within label concentration guidelines.

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