EUGENE, Ore. — At one point on the brink of extinction, winter steelhead in the Upper Willamette River system continued to show improved numbers this season.
Wildlife managers said this year’s run has been bolstered, for the second year in a row, by a program that killed sea lions preying on chrome fish near Willamette Falls.
A total of 4,760 winter steelhead have returned above Willamette Falls and spread into rivers including the North Santiam so far this year, with their projected numbers likely to reach 6,500, according to the Oregon Department of Fish and Wildlife.
That would be the highest number since 2012 and could indicate an encouraging rebound, ODFW biologist Sean Clements said. It’s still well below historic numbers that often eclipsed 20,000 in the 1980s.
“It’s definitely a hopeful sign that the run may be on the mend,” Clements said.
While Clements highlighted a number of reasons for the improved numbers — including better water and ocean conditions — he said the agency’s killing of sea lions was a big factor.
ODFW fought for years to gain the power to lethally remove sea lions that fed on roughly 20 to 25 percent of the fish that migrated past Willamette Falls, after efforts to scare away or relocate the pinnipeds failed.
Winter steelhead migrate from Oregon’s rivers into the ocean and return again, but as recently as 2017 the numbers of returning fish dropped as low as 822 and officials feared they might go extinct.
The state was granted permission to kill California sea lions in November of 2019 after a years-long process in which the state argued the pinnipeds were putting the federally-protected steelhead in “imminent danger of going extinct.”
Since then, the agency has killed 33 sea lions, all in 2019. Those were sea lions that had become habituated to eating fish at the fish ladder on Willamette Falls — basically a fish buffet — officials said.
“Two weeks ago we saw our first sea lions in almost a year at the falls,” said Bruce McIntosh, deputy fish chief of inland fisheries. “They were there briefly and have left. We have documented no predation this year and have removed none from the Willamette.”
Without killing the sea lions, around 900 to 1,100 fish from this year’s run would have eaten and would not spawn, Clements said.
While sea lion removal has helped, especially in keeping steelhead out of the “extinction zone,” Clements said there were other reasons the fish’s numbers could be up this season.