Scientific America: In the wake of dramatically dwindling populations of salmon and other fish, U.S. officials are grappling with ways to cut their losses–and stave off future damage. Overfishing and environmental damage have decimated ocean inhabitants–and climate change threatens to hurt them even more. Just this month, the Pacific Fishery Management Council in Portland, Ore., closed the coasts of California and Oregon to salmon fishing after observing an alarming drop in the species population there, which …