Examples of Rotenone Use

Rotenone is used by agencies in other states to control harmful invasive fish, illegally-introduced fish, or a diseased species at a fish hatchery. Rotenone is also used to treat waters before creating reservoirs and before restoring threatened or endangered species. It is also employed as a scientific sampling tool to study fish communities.

Rotenone has a long history of success in controlling fish when used according to EPA standards. In other areas of the United States, many water supply and fishing reservoirs had rotenone applied before stocking with fish. One example is the Strawberry Reservoir in Utah, which is now "Utah's premiere cold-water fishery". The release of live bait fish changed the reservoir so that chub, suckers, yellow perch and carp soon took over. Recreational fishing seriously declined after the illegal releases of these bait fish. Rotenone planning began in 1986, and the rotenone project was completed in 1990. The trout fishery recovered quickly, and Strawberry Reservoir is again one of Utah's most important trout fisheries.

Rotenone helped to improve the ecological quality of Diamond Lake in Oregon which was drastically diminished by the introduction of tui chub. The chub reduced the survival and growth of rainbow trout by out-competing them for zooplankton. The zooplankton that grazed on algae in the lake were depleted by the chub. The loss of zooplankton resulted in the uncontrolled growth of several forms of algae which released neurotoxins that were harmful to humans and their pets. This resulted in restrictions to boating and swimming in the lake. After the algae blooms died and decayed, the decomposition depleted oxygen from the lake, further degrading the aquatic environment for other fish. In 2006, the Oregon Department of Fish and Wildlife successfully treated Diamond Lake with rotenone. The fishery has been restored, and the lake is now safe for recreationists.

In New York's Adirondack Mountains, wild brook trout are highly sought after game fish. Since the 1950s, over 150 sites in the Adirondacks have been treated with rotenone to restore wild brook trout populations. In addition, Cornell University researchers found that by re-establishing native fish to certain ponds, such as brook trout, the native plankton populations were also restored. All forms of plankton are important food sources, either directly for fish, or indirectly for the insects that fish eat. Thus, the entire ecosystem of the pond was renewed by the reintroduction of native fishes.

Extensive public involvement is the key to success!

Most rotenone projects for fisheries restoration go through broad scientific and public review, and are just one piece of a larger fisheries management plan.

At Lake Davis in California, fishery managers with the California Department of Fish and Game (CDF&G) were concerned that illegally-stocked northern pike would escape over the dam and occupy the Sacramento River which is home to several endangered species, including native King salmon. The state planned to apply rotenone to remove the illegally-stocked northern pike, but the public was concerned about the release of rotenone into the public water supply. Public misunderstanding, lawsuits about alternate water supplies, and political positioning also contributed to polarizing the public support for the use of rotenone in this project. Neither the consequences of the illegal introduction of pike on the native King salmon, nor the renewal of the sport fishing were a focus of the media. Also, there were confrontations between pro- and anti-rotenone supporters. This highly-publicized controversy led to technical and political limitations on rotenone treatment in Lake Davis, and the lake required a repeat treatment only a few years later. It was a very costly endeavor for the State of California, and the lesson learned was that there needs to be extensive agency planning and public involvement in fishery-restoration projects involving the use of rotenone.

The CDF&G, with support from the public, again treated Lake Davis with rotenone. This project was successful, and CDF&G re-stocked the lake with rainbow trout.

The Department realizes there may be some concern about rotenone. ADF&G encourages public comments, questions, and feedback regarding plans to use rotenone for invasive northern pike eradication.