Over 25 California sea lions and an unknown number of Steller sea lions continue to prey on salmon, steelhead, sturgeon, and lamprey in the Willamette River this month. Concerns for the wild Willamette winter steelhead remain front and center for ODFW as biologists estimate that California sea lions ate at least 18 percent of the returning adults prior to March, driving this population closer to extinction.
In the absence of federal approval to lethally remove the California sea lions at Willamette Falls, ODFW attempted a stop gap program of capturing and relocating sea lions this spring. “It’s our responsibility and mandate from the people of Oregon to ensure these fish runs continue,” said Dr. Shaun Clements, ODFW’s senior policy advisor. “So it’s incredibly frustrating to us that federal laws prevent us from taking the only steps effective at protecting these fish from predation.”
During the course of five weeks in February and March, ODFW relocated 10 California sea lions to a beach south of Newport. All marked animals returned, most travelling the 210 miles within 4-6 days. One was even captured and relocated to the coast twice, but came back on both occasions. “Clearly our experience on the Willamette River this year demonstrated the futility of relocating sea lions as a way of stopping them from driving our native fish runs to extinction,” said Clements.
That’s one reason why ODFW has decided to leave its traps on the Willamette and transition sea lion operations to Bonneville – where the agency already has federal authorization to lethally remove sea lions. “It’s disheartening given what’s happening in the Willamette, but we don’t have enough staff to cover both locations so we’re moving to a place where we can be more effective,” said Bryan Wright, ODFW’s Marine Mammal Program Lead.
Currently the run of upper Willamette wild steelhead stands at 1,338, which is slightly higher than in 2017 but still well below historical runs that often topped 10,000. In contrast, the California sea lion population is exceptionally healthy and fluctuates between 250-300,000 animals. According to Wright, “Removing these few male animals that have habituated in freshwater would have no impact to the sea lion population but would provide much needed relief to fish runs and prevent similar crises from occurring elsewhere.”
ODFW has applied to the federal government for authorization to lethally remove sea lions from at Willamette Falls under Section 120 of the Marine Mammal Protection Act. Even if that application is approved, it won’t be until 2019 at the earliest. ODFW senior officials are also working with the region’s congressional delegation to address the inflexibility of the MMPA to deal with these issues in a more timely manner.
“This isn’t just about the Willamette steelhead, which we know are in serious trouble,” said Clements. “We also know that predation on white sturgeon has increased dramatically this year, and that sea lions are preying on salmon, steelhead, and sturgeon in other rivers like the Sandy and Clackamas. Effective management will only be possible if the US Congress changes the law to allow managers to proactively prevent sea lions habituating to these bottlenecks in freshwater.”
ODFW plans to leave its sea lion traps in the Willamette, continue to monitor predation, and, if the opportunity arises, trap another sea lion or two this spring. Additionally, ODFW is conducting limited monitoring of sea lions that are foraging in the Clackamas and Sandy rivers. ODFW is not authorized to do anything other than non-lethal hazing in these locations, and though hazing has proven ineffective in other systems, the department may run some hazing operations from time to time on the Clackamas River.
Source: Oregon Department of Fish and Wildlife