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NW Fishletter #390, February 4, 2019

[4] States, Tribes Gear Up To Remove Nuisance Steller Sea Lions

States and tribes preparing a joint application for the lethal removal of California and Steller sea lions that prey on salmon below Bonneville Dam were given funds to by the Northwest Power and Conservation Council to build barges needed in the effort.

The group has obtained permission in the past for lethal removal of California sea lions at Bonneville Dam, and later at Willamette Falls under an extensive vetting process to identify problem pinnipeds. Under the new federal law some of the requirements have been eased in light of the growing magnitude of the problem.

Until recently, California sea lions posed the main problem for fish managers. But Stellers--with males weighing up to 2,500 pounds (compared to the 800-pound California sea lions)--roam along the Columbia River and are now consuming about three-quarters of the total salmonid population taken by sea lions at Bonneville Dam, Kessina Lee, Washington Department of Fish and Wildlife Regional Director, told the Council Jan. 16.

These massive marine mammals initially preferred sturgeon, but have acquired a taste for salmon and steelhead. In an email to NW Fishletter, Lee said Steller sea lions now stick around the dam for 10 months of the year and are consuming about 4 percent of the steelhead run and 2 percent of the spring Chinook just below the dam.


A mother and her pup. Courtesy: WDFW

Lee and other fish managers from Washington, Oregon, Idaho and the Columbia River Inter-Tribal Fish Commission asked the Council for a one-time appropriation of up to $51,485 so they can safely trap and euthanize as many as 100 Steller sea lions that now spend most of the year below Bonneville Dam, gobbling up between 2,000 and 3,000 adult salmon and steelhead as they make their way toward the fish ladders.

The Council agreed to provide up to $52,000 from its unspent cost savings program. The money will be used to fabricate a new 10-foot by 32-foot barge that will hold and transport these massive marine mammals, and to purchase three new traps and other equipment to help catch them. The allocation allows the states and tribes to build a new barge in time for the fall Chinook and steelhead returns.

Trapping and euthanizing Steller sea lions at Bonneville Dam has become a priority partly because their numbers continue to grow, as does their impact on salmon and steelhead runs. The U.S. Army Corps of Engineers began seeing Stellers at the dam in 2003, when just three joined the 104 California sea lions camped out below the dam. Now, between 50 and 90 of the larger predators are counted at the dam each year. By contrast, the number of California sea lions at the base of the dam has fluctuated between 40 and 104 individuals since 2003. Their numbers jumped to 195 in 2015 but dropped back to 92 in 2017.

The Corps estimates that in 2017, California and Steller sea lions together ate between 4,700 and 5,230 salmon and steelhead just below Bonneville Dam. And that's just a fraction of the 24,242 salmonids consumed by both sea lion types between the dam and the mouth of the Columbia that year, researchers say.

California sea lions were initially the larger problem in the Columbia River. In 2008--five years after they started roaming up the Columbia River in large numbers--Washington, Oregon and Idaho received a permit from NOAA Fisheries to kill as many as 93 California sea lions at the dam each year, if they're observed eating salmon or steelhead in the tailrace of the dam.

In order to euthanize them, the states had to individually identify the pinniped--which requires trapping, marking and releasing them--and then document their presence at the dam for five days and attempt non-lethal removal through hazing. Under these requirements, the states have killed an average of 19 California sea lions a year. They unsuccessfully tried relocating the sea lions, only to have them return within days.


A Steller sea lion rookery, or colony with birthing mothers, on Rogue Reef in Oregon. Courtesy: ODFW

Late last year, Oregon received a new permit to euthanize California sea lions at Willamette Falls, where the sea lions are eating about one-quarter of the river's steelhead run. The Oregon Department of Fish and Wildlife said that process of removal has recently begun. So far, at least four California sea lions have been trapped at the falls and killed, said ODFW spokesman Rick Swart. He said their goal is to remove about 40. "That's the peak we've seen in recent years," he said.

Swart said it's important to realize that these sea lions are all males roaming into new territories to determine whether the habitat and food source is promising. "The importance of getting these early ones is, they aren't going back to California and taking that information back to the herd," he said. "We hope that, not only are we saving these fish, but we're also saving sea lions by short-circuiting that communication from one sea lion to another."

Swart said that while problems with Steller sea lions are part of the conversation, Oregon hasn't yet made plans to remove any at Willamette Falls. That's because they don't yet have permission for lethal removal, which only recently became possible.

The population of Stellers that live in Washington and Oregon were listed as threatened under the Endangered Species Act until 2013, and were still under special protection until 2016. But those protections were lifted with a growing population, which now includes about 12,000 animals in Washington and Oregon.

A new law also gives fish managers in the Columbia Basin additional authority to euthanize both California and Steller sea lions to help protect not only salmon and steelhead, but also sturgeon and lamprey. In December, after a decade-long effort, Congress passed the Endangered Salmon Predation Prevention Act, which allows states and tribes to trap and kill pinnipeds throughout the Columbia River below McNary Dam and in its tributaries that support Endangered Species Act-listed fish.

In a Jan. 7 letter to the Council, Lee noted that a joint application from the states and tribes seeking authority under the new law will include a request to lethally remove both California and Steller sea lions.

In a presentation to the Council's Fish and Wildlife Committee on Jan. 15, Lee showed pictures of Steller sea lions that had climbed into traps with some of the smaller California sea lions being trapped for removal. Their added weight on one side causes the traps to tilt heavily, which can prevent sea lion wranglers from moving the California sea lions out of the trap and onto the barge.

Council members--some of whom traveled to Washington, D.C., to lobby for the new law--offered not only their financial support for a new barge and traps, but also praise for the efforts and collaboration between the three states and tribes now authorized to kill sea lions in the Columbia Basin.

"It is very good to hear the states and tribes are looking at additional resources," said Councilman Guy Norman, who chairs the Council's Fish and Wildlife Committee, pointing to added staffing commitments by the states and funding requests before state legislatures. -K.C. Mehaffey

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Publisher/Editor-in-Chief: Mark Ohrenschall, Editor: K.C. Mehaffey
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