'Intersex' Fish Found In RMNP

February 28, 2008

Release from: Trevor Huges
Coloradoan (Colorado)

Trout found in five lakes in Rocky Mountain National Park have both male and female sex organs, says a massive new federal report highlighting the problems that air pollution poses for national parks.

The report released by the Western Airborne Contaminants Assessment Project said detectable levels of contaminants ranging from mercury to two banned insecticides and a flame-retardant chemical treatment were found in eight parks in the western United States, including Rocky.

The report said air pollution from coal-burning power plants is a major source of contamination, which can drift in the atmosphere for long distances before being dropped in rain or snow.

"It's certainly a cautionary lesson that supports that what goes up into our air does come down," said Rocky spokeswoman Kyle Patterson. "Parks are not immune from human activities from hundreds or even thousands of miles away."

The report said the pollution could have many different ramifications and that more study is needed.

"In Rocky Mountain and Glacier national parks, some individual trout were 'intersex,'" the report said. "This condition is commonly associated with exposure to certain contaminants (dieldrin and DDT) that mimic the hormone estrogen.”

Dieldrin and DDT have been banned as pesticides in the United States for at least 20 years. Dieldrin was manufactured for decades at the Rocky Mountain Arsenal.

The study, which began in 2002, cautioned that because the sample size of trout from Rocky was relatively small, it’s too early to make a correlation between the hermaphroditic fish and the contaminants found.

Intersex fish, while relatively rare, are more often found in waters downstream of wastewater treatment plants, living in waters contaminated with chemicals ranging from birth control pills to antibiotics. The fact that some were found in relatively pristine alpine lakes at Rocky suggests the problem may be bigger than believed.

Patterson said seven intersex fish were found in five Rocky lakes: Lone Pine, Spirit, Haynach, Haiyaha and Dream. Anglers are permitted to keep fish caught in all but Dream Lake.

She added that it’s impossible to tell which fish are intersex without a microscope.

The report said fish in all eight national parks studied, including Denali in Alaska, contained mercury at levels above that recommended for consumption by birds. Some park fish had mercury levels that exceeded the threshold for human consumption.