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At the Foot of the Bonneville Dam, Researchers
Track Voracious Sea Lions Feeding on Spring Chinook

by Quinton Smith
The Oregonian, April 18, 2011

Maybe catching the culprits on video will help prove their case.

Last week Columbia River Inter-Tribal Fish Commission researchers turned on a camera system below Bonneville Dam's second powerhouse where sea lions gather to eat migrating salmon. The tribal group wants to prove that sea lions are eating more endangered Columbia River spring chinook than humans can count.

The test is to see if the new video matches counts by six U.S. Army Corps of Engineers observers. If so, researchers will try to document sea lions harming endangered salmon at other places along the lower Columbia, not just below the dam's fish ladders.

Researchers believe the observers' count of 2 percent to 4 percent sea lion predation rate of spring chinook at Bonneville "is a gross underestimate" of what happens up and down the river, says Doug Hatch, senior fishery scientist for the Portland-based commission. The panel represents the Warm Springs, Yakama, Umatilla and Nez Perce tribes in Columbia River fishery management, research and enforcement.

The new camera system and ongoing Oregon-Washington sea lion tagging and branding are part of a complicated, years-long effort to win and keep federal approval to kill or remove some of the more voracious California sea lions from below the dam. The states had that green light for three years -- and euthanized or removed 40 sea lions -- but lost it last fall when the 9th Circuit Court of Appeals pointed at deficiencies in the National Marine Fisheries Service permit.

Rather than appeal, the fisheries service is seeing if it can address the problems and issue a new permit by the last week of April.

Sea lions at Bonneville

California sea lions became an issue a decade ago as a federal court compelled fish and power agencies to ensure greater passage of endangered spring chinook up the Columbia River. Although sea lions eat fish up and down the river, the controversy emerged below Bonneville where sea lions congregate as salmon bunch up before entering the dam's fish ladders.

Oregon, Washington and tribes want to remove or euthanize California sea lions they identify as repeat visitors to the dam and greedy eaters. The Humane Society of the United States opposes the killings and got the appeals court to stop it so far this year.

California sea lions aren't the only visitors to Bonneville. Federally protected Steller sea lions spend more time below the dam, but eat more sturgeon than salmon. So far this year observers have seen 70 Stellers taking 196 spring chinook and 1,939 sturgeon. Oregon and Washington are trying to get federal protection lifted to remove or kill the most voracious Stellers.

"Sea lions need to make a living too," Hatch says. "But there's a problem at chokepoints like Bonneville."

Still, it has been an unusual spring for migrating salmon and sea lions.

The spring chinook migration up the Columbia has been late the past five years, say Oregon Fish & Wildlife Department biologists, but this year is even later. Through Friday the spring chinook count over Bonneville was just 949; the normal count is four times that. The run is estimated to eventually total 198,000.

Predators generally follow salmon up the river to Bonneville, so low salmon numbers have contributed to 29 California sea lions observed below the dam, the fewest in eight years. Eighteen of those have been seen in previous years, according to Corps' observers.

Robin Brown, who leads the Oregon agency's sea lion research and who traps and tags the animals at Bonneville, believes removing the worst of the California sea lions between 2007 and 2010 made an impact this year. Of the 500 to 1,000 sea lions in the lower Columbia, Brown says, 100 usually come and go at Bonneville each spring.

The sea lions removed or killed, "were the early, particularly bad actors," he said. "It's a real small population of this animal that has this behavior."

Still, state and tribal biologists are fretting about late-arriving salmon and sea lions because the leading edge of the spring chinook migration has more wild, more genetically diversified fish headed for the upper Snake River. Even though there are fewer sea lions this spring-- 99 California and Stellers total -- the corps' weekly summary below Bonneville indicates they have killed 616 spring chinook so far -- or 40 percent of the run.

"We don't know for sure yet," said Hatch, "but it could be a huge problem."

Related Pages:
Cameras Go Up at Bonneville Dam to Mmonitor Sea Lions KATU

Quinton Smith
At the Foot of the Bonneville Dam, Researchers Track Voracious Sea Lions Feeding on Spring Chinook <-- Watch Video at original site.
The Oregonian, April 18, 2011

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