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Ecology and salmon related articles

Fish & Feathers: Estimates Suggest Sea Lions
Take a Hungry Bite Out of Salmon Runs

by Capt. Ron Malast
Chinook Observer, January 13, 2015

Sea lions take a big bite out of returning salmon runs

(Ron Malast photo) Marine mammals including two species of sea lions create a gauntlet between the Pacific Ocean and salmon spawning beds. With the 2015 spring salmon season just around the corner, it's interesting to take a brief look at some facts and theories about the impact of sea lions in the Columbia River. (See for details.)

NOAA Fisheries research stations monitor conditions from Point Adams at the river's entrance all the way east the Columbia River into the state of Idaho.

Since 2010, NOAA's Fisheries scientists have been collecting and PIT (Passive Integrated Transponder) tagging upriver adult spring/summer Chinook salmon in the Lower Columbia near mile 21, releasing them, and monitoring them their migration and survival to Bonneville Dam.

Survival estimates for these fish indicate that lower river mortality is significant. After accounting for harvest and impacts from the sampling process, average annual survival ranged from 69 percent to 90 percent. Analysis indicates that predation by seals and sea lions is a likely major source of mortality.

The survival rates for middle-season salmon were 89 percent in 2010, 81 percent in 2011, 82 percent in 2012, and 69 percent in 2013. Median travel time for tagged and released fish was from March 22 through May 11. Something like 45 percent of last year's spring Chinook run died between the mouth of the River and Bonneville Dam.

"When 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," a member of the Northwest Power and Planning Council said.

In 2010 as many as 7,000 pinnipeds were estimated to reside in near-ocean water and the Columbia River below Bonneville Dam for all or part of the year, including 3,000 California and Steller sea lions and 4,000 harbor seals.

The number of sea lions has increased in response to recent robust smelt runs. In 2013, the number of sea lions identified at haul-out sites near Astoria was five times more than were observed during each of the three previous years.

In 2014, the adjusted survival rate for tagged fish between March 20 and May 13 was 55 percent. Theoretical estimates of predation come to a total of 22,500 to 57,000 salmon.

New boss at WDFW

Dr. Jim Unsworth, deputy director of the Idaho Department of Fish & Game, was chosen Saturday as the new head of the Washington Department of Fish and Wildlife.

He'll have a big job ahead working out differences between the department's fish and wildlife branches, figuring out wolf management, and dealing with tough salmon allocation issues on the Columbia.

Capt. Ron Malast
Fish & Feathers: Estimates Suggest Sea Lions Take a Hungry Bite Out of Salmon Runs
Chinook Observer, January 13, 2015

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