Every year, male sea lions travel from California northward up the West Coast in search of food. Some swim as far Alaska and spend their time hunting for fish just offshore. But others, a growing number of them, enter the mouth of the Columbia River and swim 145 miles upstream—passing commercial fishing boats and shipping barges, Portland’s suburbs and freeways—to Bonneville Dam, the first in a series of hydropower systems.

There, near the base of the dam, the sea lions feast as fish such as Chinook salmon and steelhead crowd the river water before ascending fish ladders to migrate upriver. For a hungry pinniped, the entrance to the fish ladders might as well be a manmade smorgasbord.

In the last decade, Washington and Oregon state wildlife officials have killed more than 150 sea lions at Bonneville Dam and nearby Willamette Falls as a way of reducing their predation on Chinook and steelhead—two fish species listed as threatened. As Sheanna Steingass, the marine mammal program leader for Oregon Department of Fish and Wildlife, puts it, controlling sea lions is “an attempt to take away the additional pressure on [salmon and steelhead] that are being predated when trying to get upstream.” 

Some environmental and wildlife groups, however, object to the idea that it’s necessary to kill sea lions to protect fish populations. They argue that, in comparison to commercial fishing, sea lions account for a fraction of the salmon taken from the river each year. And they say that these salmon-eating predators have become scapegoats for the human development that has impacted the river and imperiled fish. “We used to have 10 to 15 million fish return to the Columbia every year,” says Columbia Riverkeeper attorney Miles Johnson. “Now we’re squabbling over a few thousand eaten by sea lions. There’s a bigger issue here that’s harder to address.”

Federal officials first allowed sea lion euthanasia under a 1994 amendment to the Marine Mammal Protection Act. At the tail end of 2018, Congress passed another amendment to the act, extending lethal removal rights to tribal fisheries managers and easing the “eligibility criteria” for identifying “problem” sea lions.

When a colony of sea lions first arrived at Bonneville Dam in 2001, tribal fishermen were among the first to notice. Sea lions had long been absent from that part of the river, having been reduced in the early 20th century to a population of around 10,000 throughout their range. The pinnipeds eventually recovered after the 1972 passage of the Marine Mammal Protection Act; today, there are around 300,000. 

The tribal officials immediately recognized that the upsurge of sea lions—along with the protections established by the MMPA—would be a problem for the Columbia River salmon runs. “Even the best laws have unintended consequences,” says Chuck Hudson, intergovernmental affairs director for the Columbia River Inter-Tribal Fish Commission, a fisheries management agency representing four Native American nations on the Columbia. “Among those consequences is when a law protects one species so much that it conflicts with the Endangered Species Act.”

The Columbia River system is home to over a dozen federally protected fish species, and over the years the federal government has poured billions of dollars into salmon recovery. Plus, to many in the Pacific Northwest, these species represent more than just a natural resource. “For the tribes, the cultural importance of the spring Chinook cannot be understated,” Hudson says. “It is the ceremonial fish. It marks the renewal of the year.”

When 600- and 700-pound sea lions started showing up and proving how much fish they can eat at Bonneville Dam—altogether roughly 3,500 annually—tribal and wildlife officials started looking for ways to save the fish.

At first, they tried nonlethal methods to haze sea lions: rubber bullets, seal bombs (a kind of firecracker), and acoustic deterrents. The sea lions kept coming anyway and in larger numbers each year. Wildlife officials then tried trapping and transporting sea lions 300 miles down the coast, but the hungry animals found their way back, sometimes in a matter of days. In 2015, the coastal city of Astoria, Oregon, found that 1,000 more sea lions had populated its marina than in the previous year, so it placed a 32-foot fiberglass orca dubbed Fauxby Dick in the mouth of the river. Sea lions watched unfazed as the inanimate killer capsized. 

Seemingly out of options, officials turned to chemical euthanasia. In 2008, NOAA gave state wildlife departments permission to trap and kill “individually identifiable” sea lions that had been observed eating protected salmon or steelhead. 

For Columbia Riverkeeper’s Miles Johnson, the lethal campaign against sea lions is a case of directing fire at the wrong enemy. 

The bigger issue, says Johnson, is the Pacific Northwest’s vast system of hydropower dams. Johnson calls the sea lion debate a “sideshow” that diverts pressure away from what he says is the true culprit: our electricity consumption. “The Bonneville Power Administration and the Army Corps of Engineers would love us all to spend our time discussing how we should be controlling sea lions,” he says, “and not discussing how we can reform the hydrosystem.”

Dams have made upstream migration difficult for the listed species on the Columbia River. Not only do sites like Bonneville Dam make it easier for predators to catch salmon and steelhead, but dams and their shallow reservoirs also contribute to increased water temperatures, making the Columbia more inhospitable to migrating salmonids. Though no serious discussion has occurred about removing Bonneville Dam (which supplies half a million homes with electricity), Johnson suggests that the removal of surplus dams elsewhere in the Columbia River system would alleviate salmons’ suffering. Already, the welfare of orcas—another marine mammal that depends on Chinook salmon—has spurred conversations on dam-breaching on the lower Snake, a tributary of the Columbia. 

Hudson and the tribal fisheries managers agree that the dams are tough on fish. But Hudson says that hydrosystem reform alone wouldn’t make sea lion predation less of a problem. “It’s not an either/or equation,” Hudson says. “When you have predation levels ranging from 17 to 45 percent of fish runs, that’s simply unsustainable.”

In other words, fisheries managers can’t be expected to sit back and watch predators devour endangered fish. “When you have increasing numbers of sea lions at these locations, doing nothing is really not an option,” says Steingass of Oregon Fish and Wildlife.

Amid all the debate, one crucial question often goes unanswered: Does lethal predator control even work? Naomi Rose, a marine mammal scientist with the Animal Welfare Institute, likens sea lions to coyotes, which have not only survived two centuries of lethal predator control policies but also colonized manmade ecosystems across North America. Kill one sea lion, she says, and another might just take its place.

“There’s always a Herschel out there who’s going to learn,” says Rose, referring to the sea lion that showed up at Ballard Locks in Seattle in the 1980s, sparking the first NOAA-authorized killings. “The ecosystem is out of whack now. That’s our fault, not theirs.”