Editor's Note: The video above this story aired on May 22, 2018.

PORTLAND, Ore. -- Wildlife officials say a plan to kill California sea lions to save an endangered run of fish on an Oregon river is working.

The Oregon Department of Fish and Wildlife says that 2,400 steelhead reached the upper Willamette River to spawn this spring - the most in three years.

Biologists say sea lions migrating from California were entering the inland river and congregating under Willamette Falls.

They gobbled up steelhead waiting to traverse the falls.

The wildlife agency has killed 16 sea lions after getting federal approval for the plan late last year.

Targeted sea lions must be observed eating at least one steelhead near the waterfall or be spotted in the same area on two consecutive days.

An effort to trap the sea lions and remove them didn't work.