Sturgeon made home in Bonneville fish ladder

NORTH BONNEVILLE — Approximately 1,700 sturgeon — ranging from a foot to 10 feet long — were found in the Bonneville Dam’s Washington side powerhouse fish ladders during routine maintenance in January.

A crew of 12 waded in knee-deep water to hand-load the fish into a water-filled tank, which was repeatedly lifted with a crane and the fish released below the dam in the Columbia River.

Congregations of sturgeon have been found before in at various sites below the dam, including in the fish collection channel that stretches the width of the powerhouse.

About 1,000 sturgeon were removed from the channel in December.

“This is new territory for us,” Ben Hausmann, a U.S. Army Corps of Engineers fish biologist, told the Columbia Basin Bulletin, an online fishery news site. “We’re not used to handling so many fish.”

The Corps routinely removes fish — steelhead and other species as well as sturgeon — when the fish ladders are dewatered for maintenance and repairs during the December-February work window when there are few spawners passing the dam.

“Why they are in the ladder I don’t know,” Hausmann said.

Observers along the top of the powerhouse saw Steller sea lions take 44 sturgeon during a four-hour stretch on the afternoon of Jan. 26, one of the four days the fish were being moved.

But only nine were preyed on in the zone nearest the Washington shore where the fish were being released.

No unusual amount of predation was observed on Jan. 25, the morning of Jan. 26 or Jan. 27.