The wild rivers of the western United States are not so wild anymore, and their inhabitants are feeling the pinch. By the late 1990s, west coast salmon populations had fallen to just 10-15% of their abundance in the 1800s¹, and at last count², 13 species of salmon and trout were listed as endangered or threatened in the United States. Environmentalists and anglers alike have a stake in restoring these fish populations — but how to accomplish that task?

We might engineer our way to a solution by building hatcheries, breeding more fish, and simply restocking the rivers. But an understanding of the evolutionary history of these fish and their potential for future evolution can help us implement this approach in smarter ways.