Sea Lions Show Big Salmon Appetite
Call it critter-cam. The U.S. Army Corps of Engineers says mounting a camera on a California sea lion might better help researchers determine what pinnipeds are doing to runs of endangered salmon in the Northwest.
“Use of a critter-cam affixed to at least one multi-year [California sea lion] early in the season would allow biologists to get a better understanding of how and where the sea lions are taking prey, and possibly if there is significant underwater consumption going on unobserved by surface observations,” the Corps said.
The video is one of eight recommendations offered by the Corps in a report released this month on the state of fish and wildlife protection, which accounts for about one-third of Bonneville Power Administration’s wholesale power costs.
The report, released less than two weeks after a House of Representatives committee endorsed expanding a program to remove sea lions from Northwest waters by lethal means, indicated a particular species of sea lion is causing more trouble.
Most of the attention in recent years has been focused on California sea lions that hover near the base of Bonneville Dam waiting for fish. But larger Steller sea lions are snapping up a larger share of fish, the Corps said.
In 2002, observers didn’t record a single Steller sea lion at Bonneville Dam. This year, the number stood at 89, with about 12 sightings per day, compared with 54 California sea lions.
Overall, from January 7 to May 31, observers at three spots near the dam along the Oregon-Washington border saw pinnipeds catch and eat 4,489 fish of different species, including about 3,970 salmon. That’s down from last year’s estimate of 6,321 salmon.
But the Corps said there’s a lot of uncertainty surrounding that number because Steller sea lions typically roam farther from the dam and do a lot of their damage underwater, where researchers can’t see them.
“The last few years, [Steller sea lions] were often observed swallowing steelhead whole, suggesting that they could consume steelhead and Chinook salmon jacks entirely below the surface,” the Corps said. “All consumption estimates provided are minimum estimates, but it should be noted that SSL predation may be underestimated more than [California sea lion] predation by the current surface observation methods.”