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Ecology and salmon related articles

Judge Denies Motion to Stop
Killing Sea Lions at Dam

by Bill Rudolph
NW Fishletter, June 8, 2012

(Thomas Boyd) California sea lions have found plentiful salmon -- and easy to catch -- at the foot of the Bonneville Dam. A lethal injection program seems to have made little difference. A federal judge in Oregon District Court denied a motion May 31 for a preliminary injunction that would keep states from lethally removing California sea lions preying on spring chinook at Bonneville Dam. By the time he announced his ruling, the marine mammals had pretty much disappeared from the scene of the crime.

The motion was filed by the Humane Society and other groups opposed to killing the marine mammals.

In his 20-page opinion, Judge Michael Simon said the arguments presented did not tip toward plaintiffs, though they had a point--that killing individual sea lions would harm the "aesthetic and recreational interests" of some people. But he said that was not outweighed by the public interest of preserving the ESA-listed salmon stocks.

In his opinion, Simon noted, "the court must take particular care not to overstep its role when reviewing the agency's selection of methodology or a decision involving a high level of technical expertise."

But he said he didn't mean to suggest that plaintiffs couldn't demonstrate a likelihood of success when they challenged the agency's conduct. He said there was still plenty of uncertainty at this stage of the proceedings, due to the complex issues, "facially plausible" explanations of defendants, and the deferential scope of review.

The judge will preside over a trial over the sea lion policy later this year, when plaintiffs square off against NOAA Fisheries and three Northwest states. Before the case was transferred from the District of Columbia, a federal judge there upheld lethal removal this year, though he reduced the number from 92 to 30. The feds say that is about the most they would actually be able to handle, anyway.

However, this spring, with the upriver chinook run returning much later than usual, fewer California sea lions have appeared at the dam than in other recent years. Only 32 different California sea lions had been identified near the dam in 2012--23 of them have been seen in previous years--with an average presence of about five animals per day, according the Corps of Engineers' May 11 hazing report.

Nine were euthanized back in April, and two more in May.

By May 1, the Corps estimated that California sea lions near the dam had eaten fewer than 500 spring chinook this year, compared to several thousand in previous seasons. The more numerous Steller sea lions were estimated to have consumed about 800 salmon. Stellers are listed under the ESA for protection, though NOAA has recently petitioned for the delisting of their eastern population.

The West Coast population of California sea lions is estimated at around 300,000 animals, according to documents filed by federal attorneys in the case. They argue that the legal removal of a few of these heavy predators on salmon would have no ill effect on the marine mammal population at large.

In recent court filings, the Humane Society argues that spring chinook harvest by humans accounts for much more significant salmon mortality than predation by sea lions near Bonneville Dam. The feds counter by saying the human impact on ESA-listed wild salmon can be reduced by harvesting only hatchery fish, while sea lions make no distinction between them. They also argue that marine mammals are likely responsible for much more predation on spring chinook in the lower Columbia River.

A declaration from Columbia River Inter-Tribal Fish Commission scientist Doug Hatch, filed March 20, included a table estimating that California sea lions have eaten about 1.1 percent of the ESA-listed spring chinook run near the dam, but more than 8 percent if predation in the lower river was included.

Using a bio-energetics model to estimate lower river consumption by sea lions, Hatch estimated that in some years, such as 2007, the rate was above 18 percent.

Over the past 10 years, Hatch estimated "that total lower river harvest (treaty plus non-treaty) on listed chinook salmon ranged from 121 to 1,283 fish, and averaged 2 percent over the 10 years. The lower river CSL [California Sea Lion] predation of listed chinook salmon ranged from 2,042 to 4,356 fish and averaged 10.6 percent over the 10 years. This predation average is five times the harvest in the lower river."

Hatch said the highest harvest occurred in 2010 at a 3.4-percent rate on one of the largest runs. But in 2007, when predation by sea lions was estimated over 18 percent, the spring run was one of the smallest in the 10-year time frame.

"This demonstrates the vulnerability of ESA-listed chinook salmon to uncontrolled CSL take, particularly in low-run years," Hatch said in his declaration, noting that he thought his estimates were on the low side because NOAA Fisheries has come up with an estimate of 12 percent of unexplained mortality for spring chinook from their own preliminary adult tagging studies in 2010 and 2011.

A declaration, filed by plaintiffs in early April from University of Montana fisheries professor Jack Stanford, took aim at the feds' methodology. Stanford said the government's estimates of CSL predation rates were "little more than guesswork." He also argued the feds had failed to address a key issue--that sea lions removed for bad behavior would soon be replaced by others.

Federal attorneys are trying to quash Stanford's declaration. Meanwhile, a schedule has been set up by Judge Simon that will assure the sea lion case is played out over the summer, starting with the administrative record to be filed in late June.

In their final report May 25, biologists surveying this year's sea lion predation said it was the first time Steller sea lions caught more salmon than the Californias. Their preliminary estimate pegged the Stellers consuming about 0.7 percent of the run near the dam, with the California sea lions eating about 0.6 percent--totalling 1.3 percent.

Bill Rudolph
Judge Denies Motion to Stop Killing Sea Lions at Dam
NW Fishletter, June 8, 2012

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