(Beyond Pesticides, October 1, 2007) For the second time in ten years, state officials have poured aquatic insecticide and piscicide rotenone into California’s Lake Davis in an effort to control an invasive species of fish, northern pike. Despite the first failure of rotenone to eradicate the pike in 1997, Fish and Game officials felt they had no alternative but to resort to the toxic chemical once more.
The invasive pike were first introduced, illegally, into Lake Davis in 1994. Since then, the population has reached uncontrollable proportions, out-competing local trout. The small town of Portola, which uses Lake Davis as its drinking water supply, is largely supported by fishing and tourism, which are boosted by its reputation for producing extremely large trout. Local businesses fear the consequences of the pikes’ destruction of the attraction.
Despite its economic concerns, the town did not universally support the first application of rotenone in 1997. Four residents, including the mayor pro tem, were arrested in a mass protest of the application as Fish and Game put thousands of gallons of the chemical in the lake. Within a year, pike reappeared.
Ten years and many failed attempted alternatives later, the pike population thrives. Fish and Game officials, in a series of community meetings, have convinced most residents that rotenone is the only option left. As a result, Lake Davis and 52 miles of tributary streams and rivers have been treated and dead fish are beginning to appear on shore.
Fish and Game has reassured the town that all traces of rotenone will be gone from the lake in five weeks. One resident said, “we’ve been told the long-term effect of rotenone on other species is negligible, [but] I’m not convinced.” Rotenone, while an “organic” pesticide, has been linked to conditions like Parkinson’s Disease from chronic exposure. Additionally, a letter from Beyond Pesticides and Defenders of Wildlife reports that
“EPA’s risk assessment of rotenone identifies several data gaps that are cause for additional concern about the chemical, including gaps on acute and chronic toxicity data for estuarine/marine fish and invertebrates, chronic risk to birds, and a lack of data to evaluate the toxicity to aquatic and terrestrial plants (raising further concerns about threatened and endangered plant species and indirect effects to threatened and endangered animals).”
Several residents have been heard to threaten reintroduction of the pike after the lake is restocked with trout, adding to fears that this application will not succeed, either. “If we don’t eradicate the pike this time, it’s probably impossible,” said Ed Pert, head of Fish and Game’s eradication effort. “I don’t want to go through this again. I don’t think anybody wants to go through this again.”