Where did the Eurasian ruffe come from?

The Eurasian ruffe (Gymnocephalus cernua) is native to freshwater and brackish waters in Europe and parts of Asia, particularly in the Baltic Sea basin and along rivers like the Volga and Danube. It was introduced to North America in the late 1980s, likely through ballast water from ships. Since then, it has spread to various lakes and rivers, often becoming invasive in some regions.