Five Harvard University studies published in the American Journal of Preventive Medicine say the fears could cause consumers to lower their consumption and lose the "substantial nutritional benefits" fish offers, USA Today reports.
"Larger, older, predatory fish have the highest level," said David Acheson, chief medical officer of the Food and Drug Administration. "Fish like salmon, which don't consume other fish, don't have the problem."
George Leonard, science manager for the Seafood Watch program at Monterey Bay Aquarium, says the good news for fish-lovers is that the fish that carry the highest health risks also are among the most endangered.
Seafood Watch recommends fish such as catfish, Pacific cod, Pacific halibut, pollock, salmon, tilapia and trout.