Risk Analysis of Invasive Freshwater Fishes in Hawaii and Micronesia

Science Center Objects

Invasive species threaten biodiversity around the world, especially on islands. USGS scientists are helping to identify fish species that have the greatest potential to invade the fresh waters of Microneisa. 

The Science Issue and Relevance: Invasive species are the second most significant driver of biodiversity loss worldwide; on islands, they are the number one reason for such loss. They also have substantial and direct negative impacts upon other critical island issues such as food security, culture, natural resources, economic development, and climate change adaptation. Invasive species are spread intentionally and unintentionally by trade, travel, and tourism.

USGS biologists sample fish and macroinvertebrates from Streams in Palau

USGS biologists sample fish and macroinvertebrates from streams on Babeldaob Island, Palau

(Credit: William J. Barichivich, USGS. Public domain.)

Methodology for Addressing the Issue: A WARC research team collaborated with local and regional scientists and experts in Micronesia and Hawaii, conducted field surveys on multiple islands, and examined available data to summarize the status of native and non-native freshwater animals, with emphasis on fishes. Using this information, they assessed the introduction risk of new invasive freshwater species into the region, evaluated the pathways by which previous introductions occurred, and identified the species that have the greatest potential to become invasive in the inland waters of Micronesia.

Map of Micronesia and political sovereignties

Map of Micronesia and political sovereignties

(Public domain.)

The principal objectives of this study were to (1) summarize available information about native and non-native macroinvertebrates, fishes, and herpetofauna of freshwater systems in Micronesia, with emphasis on Guam; (2) identify and evaluate pathways of introduction and assess the risk of introducing non-native freshwater fishes into new environments of Micronesia; (3) identify those freshwater species or groups that have the potential to become widely established or invasive in Micronesia; and (4) provide management options for preventing unwanted introductions and for mitigating risks.

Future Steps: The U.S. Department of the Navy contracted the USGS, the Smithsonian Environmental Research Center, and the U.S. Department of Agriculture Animal and Plant Health Inspection Service to produce risk assessments for invasive species that could affect freshwater, marine, and terrestrial systems in Micronesia and Hawaii. WARC scientists involved in the creation of the regional biosecurity plan will revise the freshwater invasive component to prepare draft journal articles: 1) Predicting Establishment Success of Nonindigenous Freshwater Fishes Introduced to Tropical Pacific Islands, and 2) Review of Freshwater Habitats and Aquatic Macrofauna of Micronesia.

Related Project(s) or Products: A Regional Biosecurity Plan for Micronesia and Hawaii was completed and is available online: https://www.navfac.navy.mil/navfac_worldwide/pacific/about_us/regional-biosecurity-plan-for-micronesia-and-hawaii-.html