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Development of an Environmental Assessment and Eradication Plan to Remove Tilapia from Ponds and Wetlands in National Parks on the Island of Hawai’i
Science Center Objects
Mozambique tilapia, a highly invasive non-native fish of the family Cichlidae, were discovered in a wetland in Kaloko-Honokohau National Historical Park on the Big Island of Hawai'i. As the U.S. National Park Service works to restore the natural communities and functions of wetland ecosystems on the island, the eradication of the tilapia population is considered necessary to fully achieve wetland restoration.
The Science Issue and Relevance: The U.S. National Park Service (NPS) is attempting to restore the natural communities and functions of wetland ecosystems on the Big Island of Hawai’i. Mozambique tilapia, a highly invasive non-native fish of the family Cichlidae, were recently discovered in Aimakapa Fishpond, a 30-acre brackish, lacustrine wetland in Kaloko-Honokohau National Historical Park. Tilapia and other non-native fishes are also present in other national park ponds and wetlands on the island. Eradication of Aimakapa’s tilapia population is considered necessary to fully achieve wetland restoration. Scientists with the U.S. Geological Survey (USGS) have the experience and expertise to assist the NPS. USGS scientists were recently contracted by NPS to: characterize the existing fish populations in Aimakapa Fishpond, identify the existing adverse impacts created by the presence of tilapia, identify alternatives to eradicate or otherwise manage tilapia populations, and discuss the positive and adverse impacts associated with each alternative.
Methodology for Addressing the Issue: This research project began in late 2011 and was completed in 2013. The main focus of the research was Aimakapa Fishpond in Kaloko-Honokohau National Historical Park on the Big Island of Hawaii. In addition to an extensive review of the literature, the research involved a combination of field and laboratory work. USGS scientists in charge of the project were assisted by researchers from Hawaii’s Bishop Museum. The final product will be a detailed Environmental Assessment/Eradication Plan that will discuss various eradication alternatives.
Future Needs: Invasive fishes are threats to ecosystems and native species, but introduced species are difficult to eradicate once they are firmly established or have dispersed widely. Future needs include review and modification of existing methodologies to improve efficacy, and development and testing of new chemical and non-chemical methods that may be more selective and less harmful to non-target species.