Steller sea lions are killing sturgeon at Bonneville Dam almost twice as fast this winter as in 2010, having taken at least 1,000 total since early January.
The weekly report of the U.S. Army Corps of Engineers for Feb. 18 says observations taken from dam tally 1,003 sturgeon caught by Steller sea lions between Jan. 7 and Feb 16, with another 434 unknown fish taken.
Robert Stansell, a Corps biologist, said at least 90 percent of the unknown fish are believed to be sturgeon.
“The Steller sea lions are catching many of the fish at the downstream range of our viewing area, making fish identification very difficult,” Stansell said.
Observations are made on weekdays. Weekends are not being monitored and the information is considered preliminary.
Final predation estimates will be expanded for hours and days not observed at the end of the season and presented in the Corps’ annual field report, he said.
Also observed succumbing to Steller sea lions so far are 59 steelhead, 81 shad and one chinook.
The first California sea lion was spotted at Bonneville Dam on Monday, Stansell said.
The highest daily count of Steller sea lions was 21 on Jan. 26. Corps observers have documented at least 32 individual Stellers since Jan. 20. Twenty are confirmed as being seen in past years.
Most of the sturgeon have been caught in the second powerhouse tailrace. The second powerhouse is between the Washington shore and Cascade Island.
Stansell said the record-high catch of sturgeon this winter was 122 on Jan. 11. Most sturgeon are between two- and four-feet in length.
It was mid-March in 2010 when the total of caught sturgeon reached 1,000 at Bonneville Dam. The total season observed take was almost 800 in 2009, slightly more than 600 in 2008 and slightly fewer than 400 in 2007.
No hazing of the sea lions is occurring at Bonneville Dam.
Washington and Oregon officials are waiting for a “letter of authorization” from the National Marine Fisheries Service before they are allowed to proceed with any sea lion management.
