Ecological Risk Screening Summary - Fishhook Waterflea (Cercopagis pengoi) - High Risk

Species that are considered high risk have a well-documented history of invasiveness in at least one location globally and are of establishment concern for the contiguous United States based on a climate matching analysis.

Cercopagis pengoi, Fishhook Waterflea, is a crustacean that is native to Black, Caspian, Azov, and Aral Seas of Europe and Asia. This species has broad environmental tolerance with populations in both brackish and freshwaters. C. pengoi can reproduce parthenogenetically and sexually and can produce resting eggs. In the 1990s, Cercopagis pengoi was introduced and spread in the Baltic Sea and then in the Great Lakes of North America. Since then, it has established populations in the Great Lakes Region, as well as the adjacent New York Finger Lakes Region. Ballast water and fouled fishing gear are the predominant vectors for Cercopagis pengoi introduction and spread; it can also spread through canal systems. Introduced populations have been repeatedly associated with declines in native zooplankton and planktivorous fish, sometimes changing community trophic structure. Additionally, biofouling of fishing gear by Cercopagis pengoi can result in considerable economic costs. The History of Invasiveness for Cercopagis pengoi is classified as High due to the established non-native populations and documented negative impacts of introductions. The climate matching analysis for the contiguous United States indicates establishment concern for this species. Locations with the highest climate match included areas surrounding the Great Lakes, Northeast, and Midwest. There were medium to high climate matches across most of the contiguous United States. The Certainty of Assessment for this ERSS is classified as Medium. Information was available from reliable sources, however, there was a potentially large gap in representation of the native range in the climate matching analysis. The Overall Risk Assessment Category for Cercopagis pengoi in the contiguous United States is High.