The Atlantic Bluefish Could Be A Glimpse Into How Effective Mercury Pollution Regulations Are

Mercury levels in Atlantic bluefish have been steadily declining over the past four decades — an indication that federal regulations on mercury pollution are working.

According a new study from the National Oceanic and Atmospheric Administration’s Center for Fisheries and Habitat Research, mercury levels in bluefish caught along the mid-Atlantic coastline have dropped 43 percent over the last 40 years, with an average reduction of 10 percent per decade.

“This shows that the [Environmental Protection Agency] regulations and the Canadian regulations have had a relatively huge impact on coastal ocean fish,” Richard Barber, professor emeritus of biological oceanography at Duke University and co-author of the study, told ThinkProgress. “Here is an example of rules that EPA put in place regarding mercury, and now 30 years later we see these rules potentially have a huge impact on human health and economics.”

EPA regulations and the Canadian regulations have had a relatively huge impact on coastal ocean fish

Beginning in the 1990s, the EPA began more tightly regulating mercury, banning the compound from batteries and controlling the transportation of mercury compounds used in industry. Today, coal-fired power plants are the primary sources of mercury emissions in the United States — toxic pollutants that damage air quality and contribute to ocean pollution once they eventually settle in bodies of water through precipitation. Once in water, mercury accumulates throughout the marine food chain, with predators eating mercury-tainted food, causing the mercury to build up in their biological tissues.

Bluefish, one of the most popular species for commercial and recreational fishing along the East Coast, is a top-level predator known for harboring especially high levels of mercury — so high that the Natural Resources Defense Council recommends limiting consumption of bluefish by pregnant women and children to three servings or less per month. But healthier bluefish aren’t just a public health win — they also add increased economic benefit to coastal communities and the fishing industries that depend on them.

Past studies have shown a tight correlation between mercury emitted from coal plants and mercury found in fish, Barber explained. Looking at samples of bluefish tissue from 2011, and comparing it to samples from 1972, Barber and his colleagues saw a sharp reduction in mercury levels — a drop that mirrored reductions of mercury in “atmospheric deposition, riverine input, sea water, freshwater lakes and freshwater fish across northern North America,” according to the study.

In the 1970s, the study continues, it was widely accepted that elevated mercury levels in oceans were not a result of human activity, and instead represented natural background levels — mercury spewed out by underwater volcanoes or some other naturally occurring phenomenon. The oceans, conventional wisdom said, were simply too large — anthropogenic pollution, either from air pollution or waste disposal, could not impact something so vast. But the sharp drop in mercury levels, Barber said, confirms that high levels in the 1970s were not natural background levels, and were exacerbated by mercury pollution from humans.

“We are seeing the mercury [levels in bluefish] come down as mercury pollution has been reduced in U.S. and Canada,” Barber said. “That clearly indicates that the mercury levels that we found back in the ’70s were not natural. They were not from volcanoes; they were from anthropogenic contamination.”

We know what the past and present hold, which is that the EPA regulations have a huge benefit for the ecosystem and the humans that eat that fish

Barber told ThinkProgress that he and his colleagues always had a feeling that the mercury levels that they were seeing in the 1970s weren’t from natural causes — but what surprised him, he said, is the rate at which mercury levels in fish decreased.

“The conventional estimates by the people who look at global geochemical cycles said that it would be centuries — that if you changed the inputs, it would take centuries to see changes in the ocean,” Barber said.

But that didn’t turn out to be the case. Looking at data from the 1970s through to 2011, Barber and his colleagues found a rapid reduction in mercury levels in bluefish — not over a matter of centuries, but a matter of decades.

“That is a very unexpected observation, that in ten years or 20 years you could observe a difference,” Barber said. “That’s very important, and it’s particularly important now, since EPA is into some controversial affairs having to do with the regulation of mercury.”

The EPA’s most robust attempt to regulate mercury toxins from coal-fired power plants, known as the Mercury and Air Toxic Standards, was recently dealt a blow by the United States Supreme Court. The court ruled in late June that the EPA didn’t consider costs before imposing limits on mercury pollution by power plants, and sent the rule back to the D.C. Circuit court. But even if the rule is invalidated — which is possible, though unlikely — the United States has already seen a marked reduction in toxic mercury pollution from power plants in recent years. According to Environmental Health News, between 2000 and 2012, emissions from the top 100 producing electric power producers dropped by 50 percent.

Globally, however, mercury emissions are on the rise, spurred by the use of coal in Asian countries. If global mercury emissions continue to climb, Barber warns, the impact on mercury levels in bluefish — and other marine life — remains unclear.

“We don’t know if, in the longer term, the Chinese increase in emissions is going to override the huge benefits from American pollution control,” he said. “We don’t know what the future holds, but we know what the past and present hold, which is that the EPA regulations have a huge benefit for the ecosystem and the humans that eat that fish.”

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