BETHEL — A new study by an environmental group shows that sled dogs on the Yukon River have higher levels of mercury than other sled dogs eating a commercial diet.

The mercury is thought to counteract some of the antioxidant benefits of the omega-3 fatty acids in the salmon diet.

The study looked at sled dogs all along the Yukon River as far down as Russian Mission.

It found that the higher the mercury levels in the dogs, the less antioxidants were found in the dogs. Meanwhile, the dogs fed a balanced commercial diet had what the study called a much higher total antioxidant power.

One of the study’s authors, Lawrence Duffy, says other studies have shown Omega-3 fatty acids-found in abundance in salmon-have protective properties against toxins, but mercury can prevent those benefits.

“Even though you are having antioxidants in your diet, it will lower your level of antioxidants and make you more vulnerable possibly to inflammation and other immune related problems,” Duffy said.

Still, the benefits of a salmon diet still outweigh the small levels of mercury that go a long with it. The study suggests that sled dogs-and people eating subsistence diets-should continue to eat the salmon.

Duffy says studying sled dogs can help researchers who are monitoring contaminants in the environment from climate change. He says the dogs eat the same food as people eating a traditional subsistence diet.

“One of the good things about Alaska is we have a companion up here, the sled dog, who can be used as an excellent medical model to observe these changes going on, both in the laboratory and in the field,” Duffy said.

He says they would like to pursue using sled dogs as a model in other health related studies about people living in the North.