Thursday, July 18, 2013

The Challenges of Salvaging Smelt and Other Delta Fish

Fish--including endangered species like the Delta smelt--are put in holding tanks then trucked to other parts of the Delta and released. From there, little is known about their fate. But most scientists agree it's not good. Predator often wait for what amounts to a daily feeding...A few years ago as part of a predation study, he lowered a sonar camera in the murky Delta waters to find out exactly what was going on. “We thought there might be kind of a dinner bell effect where when they heard the truck drive up they’d all come up to the site,” he says. Like Pavlov’s fish, salivating...“We could see fish kind of coming out of the pipe and on a good day you would see them kind of swim off and other days when there was predators there you would see them get picked off,” he says...Brent Bridges is a fish biologist at the Tracy fish facilities, part of the Bureau of Reclamation’s Central Valley Project. They have the same problem at their release sites. Bridges says they’re now trying to trick the predators by turning on and off the pumps at the release site. “The idea is that we want to prevent the fish, the predators, from realizing they’re going to be fed," says Bridges. "We just don’t want them to learn that when they hear the pump running they’re going to get fed.” more

No comments: