Sea lions may hit record for number of salmon eaten below Columbia dam

PORTLAND, Ore. – Most of the California sea lions have left their feeding station below Bonneville Dam but may have eaten record numbers of spring chinook salmon, the U.S. Army Corps of Engineers reports.

Hazing efforts to keep the sea lions from the schooled-up salmon searching for fish ladders to help them upriver to spawn have ended for the season. Most of the sea lions also have left.

The efforts included explosions on and under the water, rubber buckshot and beanbag rounds fired from shotguns.

Researchers observed 3,557 salmon taken below the dam. The previous record in the six years observations have been made was 3,533 in 2004 – 1.9 percent of the run that year.

This year predation below the dam is expected to be 4.1 percent because the run was smaller.

“We had a relatively low fish run” this year, said Robert Stansell, who heads up the research effort for the U.S. Army Corps of Engineers, which operates the dam.

He said sea lion consumption and fish numbers will be reviewed and updated over the summer and that an analysis of the hazing effort will be conducted.

The male sea lions have appeared at the dam in growing numbers in recent years, apparently because of an increase in the size of the spring chinook run.

One sea lion with the brand C265 was trapped and weighed near the river mouth in March at 559 pounds. He was found there again after spending more than two months below the dam and weighed 1,043 pounds.

He has been seen at the dam annually since 2002.

Observers this year identified up to 51 California sea lions at the dam on any one day.

“Evidence suggests that the increase harassment program this year did not having an overall substantial impact on reducing predation in the tailrace below Bonneville Dam nor the number of sea lions,” the Corps of Engineers concluded.

“Whether or not more salmonids would have been taken without this effort is unknown,” the group said.