CORVALLIS, Ore., April 7 (UPI) -- Research from Oregon State University shows that white sturgeon are declining because of high levels of foreign chemicals, including DDT.
Carl Schreck and Grant Feist, biologists in Oregon State University's College of Agricultural Sciences, found that sturgeon in the Columbia River in some areas above the Bonneville Dam -- east of Portland, Ore. -- have high amounts of toxic contaminants in their livers, sex organs and muscle tissue. Fish living in reservoirs behind the dams had concentrations of chemicals up to 20 times higher than those below the Bonneville Dam.
North America's largest freshwater fish, white sturgeon can grow to 20 feet in length, weigh more than 1,500 pounds and live for more than a century.
During the last 25 years, the population of white sturgeon in the upper reaches of the Columbia River has dropped sharply.
In the past, decreases in fish population were thought to be linked to the dams, which have changed the temperature and flow of the river. Fish ladders, put in place for salmon, are rarely navigated successfully by the bottom-dwelling white sturgeon, so the fish rarely expand their habitat or access oceanic food sources.
