Lake Davis, Portola, California, USA. Lake Davis is a 4,000 acre reservoir in the Sierra Nevada mountains, about 90 miles northwest of Lake Tahoe. Nonnative northern pike (Esox lucius) were illegally introduced into the reservoir, jeopardizing its outstanding trout fishery but also threatening native species downstream. In 1997, California Department of Fish and Game (DFG) used rotenone to eradicate the pike, at a cost of about $16,000,000. The project appeared to be successful until 1999 when pike were again discovered in Lake Davis; it is not known if some fish survived the 1997 treatment or if pike were illegally reintroduced after the treatment. Since 1999, DFG has tried trapping, electrofishing, even explosives to eradicate the pike but their numbers kept expanding. Finally, in 2007, DFG spent another $17,000,000 and poisoned the lake again. It remains to be seen if this eradication was successful or if some "bucket biologist" will once again illegally introduce pike back into Lake Davis and start the cycle all over.

photos: Cal Fish and Game

Learn more: http://www.dfg.ca.gov/lakedavis/