Michigan's fish consumption advisory guide became slightly more restrictive in 2009.

Allison Bush, bushalli@msu.edu
Great Lakes Echo
July 17, 2009

Those looking to enjoy a meal of Great Lakes’ fish are best off going to Lake Superior, according to a recent Canadian study.

The report compared the number of fish consumption advisories for each of the Great Lakes in 2009 to the number in 2007. Lake Superior had the least restrictive advisories, said Mike Layton, author of the report by Environmental Defence, a Toronto-based nonprofit that focuses on improving health and the environment.

Consumption advisories indicate the presence of chemical contaminants in fish.

Lake Superior does not have any advisories that are considered “most restrictive,” where zero meals of certain fish are recommended.  All the other lakes have at least three; Lake Ontario has 18.

All the lakes had more advisories in 2007 than in 2005, but there was less of an increase between 2009 and 2007, Layton said.

“So the good news is, things don’t seem to be getting too much worse,” he said.

Lake Huron was the one lake that improved between 2009 and 2007, with 11 areas becoming less restrictive than before.

Critics say report is misleading

Jeremy Holden, fisheries biologist for the Ontario Federation of Anglers and Hunters, said that the report focuses on species such as lake trout and carp instead of the more commonly eaten perch and walleye.

“The lake trout and carp are always going to be high in contaminant levels,” Holden said. “It’s going to paint a much darker story.”

The reason they have more contaminants is because they tend to live longer, so they absorb more chemicals. They are also higher on the food chain, so eating other fish gives them a chance to accumulate more chemicals, Holden said.

Layton said the purpose of his report is not to decrease fishing, but to make people aware of how pollution could affect their health.

“We don’t want to discourage people from fishing in the Great Lakes and eating fish in the Great Lakes,” Layton said. “Once that happens, we’ve lost the battle.”

On the U.S side, New York and Michigan recently updated their fish consumption advisory guides. Michigan’s became slightly more restrictive.

And although the Environmental Defence study found Lake Ontario’s fish to contain the highest number of contaminants, there was little change in New York’s fish consumption advisory from this year to last year for  lakes Ontario and Erie, said Juan Merino, media relations manager for New York’s Department of Health.

In Michigan, the updated results show an increase in mercury in Great Lakes’ fish, but also a decrease or no change in other harmful contaminants such as dioxins and PCBs.

“There’s sort-of-good news there, but also some concerning news,” said Kory Groetsch, a toxicologist at Michigan’s Department of Community Health.

Weighing mercury risk is complex

Researchers at the University of North Dakota report that mercury levels in fish might not be as dangerous as has been thought. They say if fish contain more selenium than mercury, they could be safer as damage from mercury occurs after mercury destroys the selenium supply.

But Groetsch said there is not enough data to be able to incorporate that into fish advisories.

“There’s research going on and as that occurs, we’ll take advantage of that as we can,” he said. “When you get into research, you see a variety of questions being asked – such as do the benefits of eating fish somehow offset the toxicity of these chemicals and it becomes very nuanced.”