December 29, 2016 — There’s some good news for sushi lovers. A new report finds that over an 8-year period, mercury levels in Gulf of Maine tuna declined 2 percent a year — a decline that parallels reductions in mercury pollution from Midwest coal-fired power plants.
Two years ago, Dr. Nicholas Fisher, a professor of marine sciences at Stony Brook University in New York, had a bit of luck — he found out that a colleague had established a collection of 1,300 western Atlantic bluefin taken from the Gulf of Maine between 2004 and 2012.
“They were frozen, wasn’t the entire fish, just about a pound from each fish or so. And then my colleagues and I in New York dissected out muscle tissue from each sample and analyzed it to determine the mercury content of each fish,” he says.
And as they created a timeline for mercury content for each year, taking into account the age and size of each fish sampled, a clear picture emerged.
“There was a fairly steady decline for all ages of fish, and the decline rate was approximately 2 percent per year, which doesn’t sound all that dramatic, but over 10 years it’s about 20 percent. Over two decades its about 40 percent,” Fisher says.
Most mercury pollution in this region originates from coal-fired plants in the Midwest, drifting east on the prevailing winds to drop on the coast and coastal waters. In response to regulatory and industry efforts, and to market forces, those emissions happen to have been declining by about 2 percent a year.