Circumpolar in fresh water. North America: Atlantic, Arctic, Pacific, Great Lakes and Mississippi River basins from Labrador to Alaska and south to Pennsylvania, Missouri and Nebraska, USA (Ref. 5723). Eurasia: Caspian, Black, Baltic, White, Barents, Arctic, North and Aral Seas and Atlantic basins, southwest to Adour drainage; Mediterranean basin in Rhône drainage and northern Italy. Widely distributed in central Asia and Siberia easward to Anadyr drainage (Bering Sea basin). Historically absent from Iberian Peninsula, Mediterranean France, central Italy, southern and western Greece, eastern Adriatic basin, Iceland, western Norway and northern Scotland. Widely introduced and translocated throughout Europe (Ref. 59043). Several countries report adverse ecological impact after introduction (Ref. 1739).