Their research shows that white sturgeon living in the Columbia River in some areas above Bonneville Dam have high amounts of toxic contaminants in their livers, sex organs and muscle tissue.

"We don't know the exact source of contamination," Schreck said. "The fish move, the stuff they eat moves and the water and sediments bearing the contaminants moves. The Columbia receives input from numerous sources, so any population of fish at any one site can be exposed to a myriad of substances."