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NW Fishletter #379, March 5, 2018

[9] Sea Lions Being Relocated To Save Willamette Steelhead

A California sea lion that has frequented Willamette Falls on the Willamette River since 2009 to dine on salmon and steelhead was relocated Feb. 7 to a beach south of Newport, Ore. Three days later, he was back at Willamette Falls, hungry for more fish after a return journey involving a 200-mile swim. Another sea lion--relocated a day later--was back in six days.

The Oregon Department of Fish and Wildlife says Willamette steelhead are on the verge of extinction, due to a growing number of sea lions that find their way to this easy fishing spot at the falls each year. A program to capture and relocate sea lions is the agency's latest effort to discourage these predators, now considered one of the greatest threats to the survival of wild Willamette steelhead, as well as Willamette Chinook, sturgeon and lamprey.

Last year, an all-time low of 512 steelhead crossed the falls after sea lions gobbled up about 25 percent of returning adults. This year, so far, 527 steelhead have made it over the falls in another year of predicted low returns. Steelhead will continue to migrate through May, but the run typically peaks in late February and March.

The agency, which has permission to euthanize California sea lions that prey on salmon at Bonneville Dam, applied in October 2017 for authorization to kill sea lions at Willamette Falls, and expects a decision sometime late this year.

The issue is primarily an unintended consequence of the Marine Mammal Protection Act, which puts strict limits on what the state agency can do, even while trying to protect threatened or endangered fish, Shaun Clements, ODFW's senior policy advisor told NW Fishletter in an email.

A recent study by NOAA's Northwest Fisheries Science Center found that sea lions are also responsible for taking a significant portion of the returning spring and summer Chinook below Bonneville Dam.

Clements noted that sea lion recovery has been wildly successful, to the point where there's not enough habitat to support a growing population. Instead, the mammals are moving into new environments, and have discovered the Columbia River as an abundant feeding ground.

This situation has grown over time. In the late 1990s and early 2000s, two to four sea lions could be seen catching fish at Willamette Falls, he said. Last year, there were as many as 41 in a day, all eating about three fish every day. In addition, the California sea lions--all of them males--are arriving at the falls from their breeding grounds in California earlier in the season, and staying longer. And now, biologists are spotting them at the Clackamas River, downstream of Willamette Falls.

In 2010, ODFW started hazing the sea lions, hoping to scare them away from the fish ladder entrances at the falls. Their attempts included using underwater firecrackers, and pyrotechnics discharged from a 12-gauge shotgun. Those attempts were generally unsuccessful. Once the sea lions got used to the noise, they would continue fishing, or quickly resume foraging when hazing ended for the day.

In his email, Clements said removing, or euthanizing, the relatively few sea lions that habitually return to Willamette Falls to eat steelhead, salmon, sturgeon and lamprey will have no impact on the sea lion population. Authorization would likely come with limits.

Currently, both Washington and Oregon have authority to euthanize up to 93 California sea lions each year that are eating threatened salmon and steelhead at Bonneville Dam. But before action is taken, those sea lions must be individually identifiable, and the agencies must show they were not responsive to hazing. They must also be seen eating salmonids in the Bonneville Dam area for at least five days between Jan. 1 and May 31 of any year.

According to Oregon's application to euthanize sea lions at Willamette Falls, California sea lions have recovered from fewer than 75,000 individuals to nearly 300,000. The application notes that multiple factors unrelated to sea lions were the initial cause of declining Willamette fish populations--primarily the impact of dams for hydropower and flood control, along with harvest and hatcheries.

Regardless of why fish numbers initially dropped, the application states, "in areas where salmonid abundance is low, even a modest increase in predation by pinnipeds can result in serious negative impacts to the survival and recovery of individual salmonid populations."

Clements noted in his email that although predation is a recent threat, if nothing is done, investments made to address other threats to salmon and steelhead recovery are at risk. "Sea lions are not a scapegoat for addressing other threats to fish persistence. That work is ongoing and the region continues to invest millions in recovering salmon/steelhead," he wrote. -K.C. Mehaffey

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NW Fishletter is produced by Energy NewsData.
Publisher/Editor-in-Chief: Mark Ohrenschall, Editor: K.C. Mehaffey
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