Oilsands have not increased mercury levels in Athabasca fish, scientists’ study finds

Oilsands have not increased mercury levels in Athabasca fish, scientists’ study finds
Islands on Lake Athabasca, as seen from Fort Chipewyan.Photo: Michelle Swallow.

Mercury concentrations in fish in the Athabasca River ecosystem are not being affected by increasing oilsands development, according to a report published last week by two Environment Canada scientists.

The study, Investigations of Mercury Concentrations in Walleye and Other Fish in the Athabasca River Ecosystem with Increasing Oil Sands Developments (Mercury in Fish) by Marlene S.

Evans and André Talbot, is based on mercury concentration data from fish caught during 1975-2011 from the Athabasca River, Clearwater River, the Peace-Athabasca Delta, Lake Athabasca and surrounding lakes.

More than 1,600 fish, including 630 walleye, 415 lake whitefish, 445 northern pike and 105 lake trout samples were assembled from a database of federal, provincial and industry-funded data sources and analyzed for mercury concentration.

“While mercury emission rates have increased with oilsands development and the landscape (has) become more disturbed, mercury concentrations remained low in water and sediments in the Athabasca River and its tributaries and similar to concentrations observed outside the development areas and in earlier decades,” the authors stated.

They found that in the immediate oilsands area of the Athabasca River, mercury concentrations decreased in walleye and lake whitefish over 1984-2011. Similarly, mercury levels decreased in northern pike in western Lake Athabasca and its delta between 1981 and 2009. No trend was evident for walleye (1981-2005) or lake trout (1978-2009).

The study revealed that mercury levels in lake trout from Namur Lake west of the oilsands area were higher in 2007 than 2000, but the authors pointed out this might not have to do with oilsands.

“It is difficult to ascribe this increase to an oilsands impact because similar increases in mercury concentrations have been observed in lake trout from similar sized lakes in the Northwest Territories,” they said.

Both authors stated that future monitoring programs investigating mercury trends in fish should be “more rigorous” in their design.

According to Evans and Talbot, the study was done in response to one completed by independent biologist Kevin Timoney and Peter Lee of Global Forest Watch in 2009. Performed over a three-year period, Timoney’s study reported increasing mercury in walleye from the Athabasca River, and attributed the increase to expanding oilsands development.

Timoney said the study done by Evans and Talbot was a welcome addition to literature on the subject, but said the lack of trends does not indicate a lack of connection between industry and toxins in the environment.

“The lack of evidence for an increasing trend in fish mercury concentrations is encouraging, but should not be generalized beyond the limitations of the data,” Timoney told The Journal in an email. “The industrial release of a host of environmental contaminants into air, land and water has been well-documented. It would be unreasonable to conclude that the environment, wildlife and humans will be immune to the effects of industrial contaminants. It is dangerous to confuse failure to find an effect with lack of an effect.”

Federal Environment Minister Peter Kent said the study exemplified the kind of “world class” oilsands monitoring taking place through the recently launched Canada-Alberta joint monitoring plan.

“This research will help build a comprehensive, scientifically-grounded understanding of baseline environmental conditions in the oilsands region in order to properly assess changes over time,” Kent said.

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