New York Times: On a boat in the heart of Californias biggest river delta, a researcher pored over a sample of murky, weed-infested water, looking for a rare fish about the size of a finger. Spotting one, he shouted in triumph then measured it and quickly tossed it overboard. Theyre very fragile, explained the researcher, Greg Nelson, who works as a biological science technician for the federal Fish and Wildlife Service, as the silvery fish darted away. The tiny fish, known as the delta smelt, has helped...