Sea lions chomped about 20 to 25 percent of this year's winter steelhead run in the Willamette River as these adult fish tried to ascend the fish ladder at Willamette Falls.
That's a problem because just over 500 native winter steelhead passed the falls in 2017, the lowest run size ever recorded, Shaun Clements, senior research scientist with Oregon Department of Fish and Wildlife, told the Northwest Power and Conservation Council Sept. 12.
ODFW recently applied for a lethal take permit in an effort stem the losses caused by 40 or so sea lions, whose numbers have steadily increased since 2015.
The run has been in trouble for a while, and NOAA Fisheries listed the upper Willamette River winter steelhead as threatened under the Endangered Species Act in 1999, citing the impact of federal dams and loss of habitat.
But now the immediate threat is from California sea lions, said Clements, who pegged the probability of Willamette River winter steelhead extinction at 89 percent.
Clements and Steve Jeffries, research scientist for Washington Department of Fish and Wildlife, said the California sea lion population has grown along the West Coast over the past 40 years to nearly 300,000 animals.
A small proportion of male sea lions have expanded their range into freshwater areas, such as Willamette Falls, where migrating salmon and steelhead congregate before moving upstream.
Jeffries said sea lions have now been spotted in or near the Columbia River tributaries of Cowlitz, Lewis, Sandy and Clackamas rivers, and are known to eat lamprey, sturgeon, and ESA-listed eulachon, as well as salmon and steelhead.
Even though California sea lions are sheltered by the federal Marine Mammal Protection Act (MMPA), the lethal removal of a few problem animals would not have an effect on the overall sea lion population, Clements said.
Clements and Jeffries emphasized in their presentation to the Council that non-lethal methods tried over the past two decades have not worked. The one exception was physical barriers at dam fishways. Acoustical deterrents at fish ladders, hazing and trap-and-release have failed to deter the sea lions.
Lawmakers in Congress have introduced bills to ease the federal permitting process for killing problem sea lions under the MMPA.
The House bill, HR 2083, is sponsored by Rep. Jaime Herrera Beutler (R-Wash.) and Rep. Kurt Schrader (D-Ore.); while the Senate's bill, S. 1702, is sponsored by Sen. James Risch (R-Idaho).
"Given the situation at Willamette Falls, everyone is united in their call for swift action, and ODFW stands ready to provide expertise to the Northwest congressional delegation on a bipartisan, compromise bill to revise the MMPA to address these emergency situations," Clements was quoted in an Aug. 7 ODFW news release.
Not quite "everyone is united in their call," however.
The Conservation Angler and the Willamette Riverkeeper sued the U.S. Army Corps of Engineers in May, hoping to stop the production and release of non-native summer steelhead
in the Willamette River basin. ODFW operates the Corps-owned hatcheries.
The two conservation groups hope to persuade a federal judge that these non-native hatchery steelhead are competing with the native wild winter steelhead for habitat and food and are a major reason for the decline of the ESA-listed native species. -Laura Berg