The Galapagos and Beyond: Eradication of Invasive Fishes on Tropical Pacific Islands

In 2007-2008, U.S. Geological Survey biologists assisted Galapagos National Park personnel in the development of a plan to eradicate a reproducing population of tilapia introduced to a 4.9-h volcanic lake on Isla San Cristobal in the Galapagos Archipelago, Ecuador. Rotenone was applied to the lake in January 2008, resulting in the removal of an estimated 40,000 tilapia. Since that date, no live tilapia have been collected or observed at the site. Following that project, I began compiling information on past and ongoing non-native fish eradication efforts on other islands in the tropical zone of the Pacific. Over 60 non-native species of freshwater fishes, representing 18 families, are established on Pacific islands, especially common are members of the families Cichlidae (e.g., tilapias), Poeciliidae, Centrachidae, Cyprinidae, and Loricariidae. I found information on past or present invasive fish eradication efforts for the Hawaiian Islands, Nauru, Kiribati, Palau, Guam and Fiji.  The main fishes targeted have been tilapias (family Cichlidae) and live-bearers (Poeciliidae). A few projects can be judged to have been fully or partially successful.  Successful projects were those that targeted small inland water bodies (e.g., artificial ponds, anchialline pools) and relied heavily on the use of chemical ichthyocides, typically rotenone to achieve their goals.