LONGVIEW — Sea lions may be killing more returning salmon at the mouth of the Columbia River than previously thought, according to research on fish survival.
Preliminary research by NOAA Fisheries shows a steady increase in fish mortality over a five-year period that may be attributable to seals and sea lions, the Northwest Power and Conservation Council said.
A NOAA researcher presented numbers Tuesday to a council committee meeting in Portland, The Daily News reported.
The average spring Chinook salmon survival in 2014 at Bonneville Dam was just 55 percent, down from 69 percent in 2013 and 82 percent in 2012.
“Even I have a hard time believing those numbers, but at least through 2013, estimates of fish mortality do fall within theoretical estimates of predation,” lead researcher Dr. Michelle Wargo-Rub of the Seattle-based Northwest Fisheries Science Center told the Council’s Fish and Wildlife Committee.
Wargo-Rub and her research team catch and tag salmon in the estuary near Astoria. More than 2,200 salmon have been tagged since the research project began, and of those, about 68 percent were determined by genetic testing to be destined for the river and tributaries above Bonneville.
Council member Bill Booth of Idaho called the research quite disturbing.
“If predation is really 30-40 percent of the spring run over the last couple of years, and the region is directing more than half a billion dollars a year to fish and wildlife recovery, and nearly half of the spring run is being consumed by seals and sea lions, then we definitely have a problem,” he said.
The number of sea lions observed at haul-out sites near Astoria by Oregon Department of Fish and Wildlife staff increased from 72 in 2011 to 616 this year.
Since 2008, Washington and Oregon have been trapping and killing California sea lions at the dam. Fifteen were trapped this year.
The trapping program was the subject of an unsuccessful law suit from the Humane Society of the United States.
