Dams seen driving 'mass extinction' of salmon

摘要

For millennia, Native Americans subsisted on a spring run of chinook salmon returning to the Klamath River inrnNorthern California.rnThat changed when the last of four dams was built on the river in 1962 and the number of "springers" plunged, arncatastrophic turn missed by federal regulators who lumped together the spring and fall salmon runs.