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Bonneville Dam Gates Fail to Keep Sea Lion Out

by Jim Parker, March 8, 2006

North Coast fishers tackle consequences of climate change

CASCADE LOCKS, Ore. -- A single sea lion has managed to squeeze through strong gates designed to protect salmon at Bonneville Lock and Dam and the U.S. Army Corps of Engineers said Wednesday it is worried that other sea lions may follow.

Sea lion C-404 has managed to find a way through gates designed to keep him out of the Bonneville Dam area.

The Corps spent $1 million to install a dozen gates about a month ago to keep sea lions from gobbling up endangered salmon on the ladders at Bonneville.

The sea lion exclusion devices, which consist of steel racks, were placed at several fishway entrances at the dam's powerhouse on the Washington side, at a second powerhouse and the spillway.

While the devices contain only 15 1/2 inch gaps between metal bars, the gap size apparently wasn't small enough to prevent the lone sea lion, tagged by wildlife officials and identified as C-404, from getting into the fishway.

The animal also was undeterred by audio devices installed near the fishway entrances that produce uncomfortable sounds for sea lions.

"C-404 is a very smart animal that has learned how to get where he wants to go, despite our best efforts," said Robert Stansell, a Corps biologist at Bonneville Dam. "He ignored the acoustic deterrents, even though to a sea lion they are as loud as a jet engine if you are right near the transmitter."

Stansell said the Corps is now concerned about the potential for other smaller-sized sea lions to follow C-404's lead.

"It is a tight fit through the bars, so he's very determined to get there," Stansell."We believe most sea lions though will be deterred with the acoustic and exclusion devices."

The gates were designed to keep sea lions out while still allowing for thousands of Coho, Chinook, steelhead and Sockeye salmon to travel through Bonneville to spawn from March to November. Over the past decade, a half million salmon went through the dam, officials estimate.

Since the Marine Mammal Protection Act was passed in 1972, the population of sea lions has risen tremendously in Oregon, according to the state Department of Fish and Wildlife.

ODFW estimates there are roughly 15,000 to 20,000 California sea lions that come north to Oregon every year.

Jim Parker
KGW environmental reporter Vince Patton and the AP contributed background to this report.
Bonneville Dam Gates Fail to Keep Sea Lion Out, March 8, 2006

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