Economic Importance for Humans: Negative
When introduced outside their native range, brown trout compete with and prey upon native trout and other fish and amphibian species. Introduction of brown trout has been associated with declines in native brook trout in the eastern U.S. and frog species in the west. In some locations, brown trout may act as a prey base for parasitic sea lampreys (Petromyzon marinus). This may increase lamprey pressure on other native species. Introductions of brown trout may also bring fish diseases that can attack native species as well.