Sea lions blamed for low salmon levels

The U.S. Army Corps of Engineers temporarily removed two sea lion exclusion devices at a Bonneville Dam powerhouse Monday to try to see if they are behind the low numbers of salmon passing upriver to spawn.

Fishery agencies in Oregon and Washington requested the trial removal of the sea lion exclusion devices, or SLEDs, for two days. The devices are intended to keep hungry sea lions out of the fishways while allowing free passage for salmon. The experiment had tribal and governmental support.

"There is no indication that fish are being blocked by the SLEDs, and fish counts doubled over the weekend," said Robert Willis, environmental branch chief with the Corps of Engineers. "For whatever reason, it seems the migration is, like last year, very late."

By late last week, only 316 chinook had crossed Bonneville Dam compared to the 10-year average for that period of more than 59,000.

Washington Department of Fish and Wildlife Director Jeff Koenings said the SLEDs are of the best design available, but there is concern about the low passage rate.

Only two of the 12 SLEDs were removed. Passage of fish there and elsewhere will be monitored together to determine if there is a difference.

The U.S. Army Corps of Engineers said it will do what it can to shoo the sea lions away during the test. Sea lions gather at the base of the dam, where the fish accumulate on their way upriver, to get an easy meal. They ate an estimated 3.5 percent of the run last spring.

The steel SLEDs range in size between 30 feet and 36 feet high and between 10 feet and 16 feet wide. The gaps between the bars in the devices measure 15 1/2 inches, and so far only one sea lion, branded as C-404, has been able to squeeze through.