Biologists with the Army Corps of Engineers say they discovered the largest gathering ever of white sturgeon on the Columbia River. It happened in February.

The number of fish staggered biologists, who estimate as many as 60,000 gathered on the river floor near the Bonneville Dam.

“It’s quite unusual,” said marine biologist Dennis Schwartz with the Army Corps of Engineers.

“We don’t understand the behavior,” he said.

Schwartz said the discovery began last winter with an investigation into possible erosion near the spillways.

The dam was not spilling water at the time.

“We identified a pile of what we considered debris,” near Bay #2 said Schwartz.

Divers were sent down to investigate the debris---and found all the sturgeon.

Schwartz estimates sizes ranged from one foot to 14 feet long.

He said there were enough to fill 360 big dump trucks.

The fish are no longer gathered near the dam. They dispersed when the Army Corps began spilling water to help move young salmon down stream.