Ecological Risk Screening Summary - Ayu (Plecoglossus altivelis) - Uncertain Risk

Species that are considered uncertain risk need a more in-depth assessment beyond the Risk Summary to better define the species’ risk to U.S. environments.

Ayu (Plecoglossus altivelis) is a species of salmonid that is native to the western Pacific and eastern coastal areas of Asia, including Japan, the Korean Peninsula, China, and Taiwan. P. altivelis has both amphidromous and landlocked freshwater forms. The amphidromous form reproduces in freshwater and spends summer months foraging in freshwater. This assessment did not consider any marine information or use any marine locations for the climate match. P. altivelis is a highly prized commercial fish that has been caught at high levels in the past. It is used in commercial aquaculture throughout its range. The history of invasiveness for P. altivelis is classified as No Known Nonnative Population. P. altivelis was intentionally introduced to Hawaii and California in the early and mid-20th century; introductions failed to establish a population in both locations. Other introductions in China, Russia, and Ukraine were also the result of intentional stocking and either failed (Russia) or the status is unknown (China and Ukraine). No information was found on actual or potential impacts of introduction. The overall climate match for the contiguous United States is high. Most of the eastern United States, including the eastern Plains States, had medium to high matches, except for coastal New England and the interior areas of the Gulf States. The certainty of assessment is low due to lack of information. The overall risk assessment category is Uncertain.