ChiefsPlanet - Sea Lions!

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A sea-lion bull chows down on a spring chinook near the base of the Bonneville Dam. California sea lions are gathering in increasing numbers below the dam to feast on salmon and steelhead preparing to enter the fish ladders.

BONNEVILLE DAM — At the Bonneville Dam, more than 140 miles from the Pacific Ocean, spring has emerged as the season of the sea lion. Dozens of bewhiskered bulls congregate in pursuit of prized Columbia River chinook that this year, so far, are in acutely short supply.

As of late Tuesday, about 200 of the spring chinook, which are protected under the Endangered Species Act, had gone through the dam's fish passage, compared with the 10-year average of 3,085 for the same date. It's the worst early showing in decades, with biologists unsure whether this run of hatchery and threatened wild salmon is very late, very weak or some combination of the two.

To protect those salmon milling below the dam, the biologists are preparing a sea-lion battle strategy that includes noisemakers, sonar and eventually grates to keep them out of the fish ladders, an effort reminiscent of the Seattle campaign in the 1980s and '90s to keep sea lions away from steelhead moving through the Ballard Locks.

"Even if they're only taking 20 [salmon] a day, that's a huge percentage of what is actually going through the dam," said Robert Stansell, an Army Corps of Engineer biologist who has spent the past three years studying the spring show of sea lions at the Bonneville Dam, about 40 miles east of Portland. "And right now, we really don't have a good count."

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Two bulls squabble over position at the base of the dam. They may soon be occupied with more-pressing matters: Federal biologists began experimenting this week with noisemakers to try to keep the hungry interlopers out of the Bonneville Dam's fish ladders.

Through most of the past century, sea lions were an infrequent sight at Bonneville. But their numbers have soared since the 1970s, their West Coast population more than tripling to surpass 300,000. The bulls, which stray far from California breeding grounds in pursuit of food, appear to have discovered that the Columbia River dam forms a major choke point for salmon.

For the past three springs, more than 100 bulls have shown up at Bonneville. They stay through the peak of the run of spring chinook, which has been a focal point of a federal Columbia River salmon-recovery effort that stretches back more than a decade and has soaked up billions of dollars. Some of the sea lions appear so comfortable that they sun on the concrete ramps of the dam's spillway.

Sea lions do not determine the fate of a spring chinook run, which may be reduced by factors such as drought in freshwater spawning grounds, the number of young salmon killed passing downstream through dam turbines and poor feeding conditions in the ocean. The 2004 spring chinook run was strong, despite sea lions catching some 3,900 fish, about 2 percent of the fish that arrived at the base of the Bonneville Dam, according to Stansell's study.

Biologists are debating what has caused the early part of this year's run to falter at the dam. The fish could have faced unexpected hardships at sea. Or, perhaps, most arrived safely at the mouth of the Columbia but for some reason stacked up downstream waiting for the right moment to surge inland. The run was initially expected to top 250,000 past Bonneville but may fall well short of that forecast.

With fish passage at the dam so weak, the number of fish eaten by sea lions is a much greater concern this year. After meetings with the National Marine Fisheries Service, biologists began to experiment this week with noisemakers to try to keep sea lions out of the dam's fish ladders. At least two of the bolder bulls pursued salmon into the concrete confines, offering tourists an unexpected sight through the underwater glass at a visitors center.

Yesterday, biologists scored an initial success as a high-school volunteer scout sighted one of those bulls — branded with the number 404 — inside a fish ladder. A pistol-wielding biologist shot blanks known as a "screamers" at the sea lion.

"He [the bull] dove very quickly, and that's the last we've seen of it," Stansell said.

By next week, federal biologists hope to have three sonar devices operating near the mouth of the fish ladders. They hope the devices will emit underwater sounds spooky enough to keep the sea lions at a greater distance.

Failure at Ballard Locks

The Bonneville Dam tactics piggy-back on the work done at the Ballard Locks, which in the '80s emerged as a favorite spot for sea lions.

Army Corps of Engineers biologist Robert Stansell, right, confers with Jeff Burnett, a high-school senior from Gresham, Ore., who records sea-lion activity at the Bonneville Dam.

The Seattle effort included trapping the sea lions, shooting them with rubber-tipped arrows, broadcasting fake killer-whale sounds, exploding underwater fireworks and other tactics, but it ultimately proved to be a losing effort to save the steelhead.

"The run we were trying to protect essentially doesn't exist anymore," said Steve Jeffries, a Washington Department of Fish and Wildlife biologist who worked with sea lions at the Ballard Locks and has consulted on the Bonneville situation.

Jeffries said that protecting fish at the Bonneville Dam poses a bigger challenge because it's a much larger structure, with four fish ladders and eight entry points. Sonar does not work well in bubble-rich water such as the stretch of river below the dam. It also does not do much to deter sea lions that already associate the dam with fish, Jeffries added.

Stansell acknowledged that the system may not work well but wants to give it a try. "We'll just have to wait and see, and evaluate it," Stansell said.

The buildup of sea lions also is tracked by sport fishermen pursuing chinook by boat and along the banks. They said fishing has been spotty, with the added frustration of sea lions occasionally stealing the fish they hook.

Even when the sea lions aren't snatching fish, anglers said, their presence scares away the chinook. A few said they wished they could dispatch the sea lions with live ammunition, which is prohibited by federal marine-mammal-protection laws.

But Jeff Smith of Portland said he likes sea lions and almost got in a fistfight with other anglers who were throwing stones to try to scare sea lions away from a hooked fish. "I don't care if I get a fish or not, they [the sea lions] are just up here trying to survive," Smith said.

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Hal Bernton: 206-464-2581 or hbernton@seattletimes.com [/IMG]