Sturgeon having a ball in Columbia River

When sonar surveys spotted a vast pile of rubble in the Columbia River below Bonneville Dam late last winter, officials suddenly worried part of the dam structure was eroding into the river.

What they found below the spillways in February was not a giant pile of rock at all, but a humongous pile of thousands upon thousands of sturgeon - some of them 14 feet long or longer - lounging together in frigid water at the bottom of the river.

The mountain of white sturgeon contained around 60,000 fish, according to a crude estimate by Michael Parsley, a research fisheries biologist with the U.S. Geological Survey's Columbia River Research Laboratory in Cook, Wash. He described that estimate as "probably conservative."

It was an aquatic phenomenon nobody had ever seen at such a monstrous scale, offering a startling glimpse into the life of the Columbia's largest and most ancient fish.

Source: Oregon Live
Photo: Columbia River Trophy Sturgeon Fishing