PORTLAND, Ore. — Oregon wildlife officials have started killing California sea lions that threaten a fragile and unique type of trout in the Willamette River, a body of water that’s miles inland from the coastal areas where the massive carnivorous aquatic mammals usually congregate to feed.
The state Department of Fish and Wildlife obtained a federal permit in November to kill up to 93 California sea lions annually below Willamette Falls south of Portland, Oregon, to protect the winter run of the fish that begin life as rainbow trout but become steelhead when they travel to the ocean.
As of last week, wildlife managers have killed three of the animals using traps they used last year to relocate the sea lions, said Bryan Wright, project manager for the Oregon Department of Fish and Wildlife’s marine
The adult male sea lions, which weigh nearly 1,000 pounds (454 kilograms) each, have learned that they can loiter under the falls and snack on the vulnerable steelhead as the fish power their way upriver to the streams where they hatched.
The trout travel to sea from inland rivers, grow to adulthood as steelhead in the Pacific Ocean and then return to their natal river to spawn. They can grow to 55 pounds and live up to 11 years.
The sea lions breed each summer off Southern California and northern Mexico, then the males cruise up the Pacific Coast to forage. Hunted for their thick fur, the mammals’ numbers dropped dramatically but have rebounded from 30,000 in the late 1960s to about 300,000 today because of the 1972 Marine Mammal Protection Act.