Survey: Fish tainted throughout West

Oregon scientists looking for fish tainted by mercury found them in every fish and every river they sampled across the West, suggesting that industrial pollution generated around the world is likely responsible for at least some of it.

The survey of 2,707 fish randomly collected from 626 rivers in 12 states represents the biggest regional sampling yet of mercury in fish in the West, said Spencer A. Peterson, at EPA’s National Health and Environmental Effects Research Laboratory in Corvallis.

The findings by scientists from the EPA and Oregon State University were reported in the January issue of the journal Environmental Science & Technology.

Though the survey found some fish with elevated mercury levels, suggesting a local source such as an old mercury mine, most levels were low, in line with canned tuna found in grocery stores, said OSU researcher Alan T. Herlihy.

No attempt was made to specifically link the mercury in the fish to mercury in the atmosphere, but the low but widespread levels suggest the mercury came from deposition – mercury in the atmosphere falling to the earth in rain and snow.

While generally below levels considered unsafe for people to eat from time to time, the mercury could pose a danger to fish and wildlife that depend on fish for their diet, said Robert M. Hughes, a fisheries and wildlife research associate professor at OSU who took part in the study.

Levels were generally higher in fish-eating fish, such as bass, walleye and pike, than in insect-eaters, such as trout.

“What’s important to note is that the levels are below what we consider a health concern in most fish,” said EPA spokeswoman Suzanne Ackerman.

Elevated mercury levels have been linked to learning disabilities and developmental delays in children and to heart, nervous system and kidney damage in adults.