California hopes to fool fishes
Central Valley Business Times
02/24/2011
Would you swim through a curtain of air bubbles blasted with bright flashing lights and noise? The California Department of Water Resources hopes that salmon won’t.
It plans to install the equipment in the Sacramento River near Walnut Grove in an effort to deter ocean-bound Chinook salmon from leaving the main channel to take a risky detour into Georgiana Slough.
That route leads young salmon through “predator-infested waters” toward huge state and federal water export pumps near Tracy, the department says.
The slough is a watery equivalent to the Bates Motel of horror movie fame -- 65 percent of the young salmon that enter Georgiana Slough don’t survive, eaten by striped bass or other predators or lost to pumping operations of the State Water Project and Central Valley Project in the southern Delta.
DWR will begin installing the bubble curtain as early as this week at the head of Georgiana Slough. The barrier structure will be installed deep enough to allow at least 9 feet of clearance for boaters on average low tides.
The barrier will utilize “Bio-Acoustic Fish Fence” technology, combining acoustics and a strobe-lit sheet of bubbles to create an underwater wall of light and sound at frequencies that repel young salmon, DWR says.
This is the same technology DWR used at the head of Old River in the south Delta in 2009 and 2010 where it was proven effective in deterring salmon, the department says.
