Abundant hatchery salmon mask weak numbers of wild fish

Among Chinook salmon returning to California’s Mokelumne River to spawn in 2004-5, hatchery-raised fish far outnumbered wild fish, according to a recent study led by an ecologist from University of California, Santa Cruz.

Most hatchery fish in the Mokelumne River aren’t marked, so the researchers analyzed chemical markers in ear bones from salmon carcasses to distinguish between wild and stocked fish. They found only 4 percent of the Chinook returning to spawn were born naturally.

The study raises questions about the viability of wild Chinook populations the role of hatchery programs in salmon conservation, according to a report from the New York Times.

Read more at the New York Times

Image credit: U S Department of the Interior