- Title: Lower mercury levels in Atlantic bluefin tuna linked to lower emissions
- Date: 12th December 2016
- Summary: AT SEA - OFF THE COAST OF SPAIN (FILE - MAY 12, 2009) (ORIGINALLY 4:3) (REUTERS) VARIOUS OF BLUEFIN TUNA ON BOAT
- Embargoed: 27th December 2016 16:57
- Keywords: bluefin tuna tuna mercury environment pollution coal emissions
- Location: STONY BROOK, NEW YORK + CUMBERLAND, TENNESSEE, UNITED STATES / AT SEA / UNIDENTIFIED LOCATION / TOKYO, JAPAN
- City: STONY BROOK, NEW YORK + CUMBERLAND, TENNESSEE, UNITED STATES / AT SEA / UNIDENTIFIED LOCATION / TOKYO, JAPAN
- Country: USA
- Reuters ID: LVA0025CKXIL7
- Aspect Ratio: 16:9
- Story Text: EDITORS PLEASE NOTE: THIS EDIT CONTAINS MATERIAL WHICH WAS ORIGINALLY 4:3
Over the past decade Atlantic bluefin tuna have become safer to eat.
According to a study published in Environmental Science and Technology, the mercury levels in Atlantic bluefin tuna have reduced since 2004 and that reduction mirrors the reduction of mercury emitted from coal-fired power plants in the U.S.
The research was conducted at Stony Brook University in New York.
Stony Brook University Professor of Marine Science at the School of Marine and Atmospheric Sciences, Nicholas Fisher, said two years ago that he was given access to a trove of Atlantic bluefin tuna caught in the Gulf of Maine. The 1,300 fish were caught between 2004 and 2012.
Stony Brook University graduate student Cheng-Shiuan Lee was on the team of researchers that analysed each sample for its mercury content.
What they found was surprising.
"We saw that the concentrations of mercury in fish captured in 2012 were lower than the concentrations of similarly-sized fish captured in 2004 and likewise all the dates in between. So there was a pretty steady decline in the mercury concentration in these fish captured from 2004 to 2012," said Fisher.
"The decline is only two percent per year, which doesn't sound that dramatic, frankly. But for ten straight years that becomes like a 20 percent decline. Two decades - it's a forty percent decline. So we're talking about some fairly significant declines," he said.
Atlantic bluefin tuna make for good test subjects because they can live for a long time compared to other fish. Atlantic bluefin tuna can survive well into their 20s and 30s and their eating and migration patterns take them all over the Atlantic Ocean.
Due to the Atlantic bluefin tuna's wondrous oceanic travels, this research could indicate ocean-wide changes, rather than local changes.
Also, Atlantic bluefin tuna are large fish and thus have very high concentrations of mercury. For humans, eating bluefin tuna accounts for about 40 percent of all mercury exposure to people living in the U.S.
Mercury is known to be toxic to nerve function in very high doses.
Fisher said the reduction of mercury levels parallels the reduction of mercury emissions from coal-fired power plants in the U.S.
"What was curious as well is that the rate of decline in the bluefin tuna mercury concentrations parallel the decline in mercury emissions from North America, which declined at about that same rate over that same period of time. It also paralleled the decline in mercury concentrations in the air above the North Atlantic and declines in the dissolved mercury in the surface waters of the North Atlantic where these fish tend to live. So it seemed that the fish were responding almost in real time," he said.
According to Stony Brook University, this is the first evidence to suggest that emission reduction efforts have resulted in lower mercury contents in Atlantic bluefin tuna.
Fisher is, though, quick to note that the research does not conclusively link the falling levels of mercury in Atlantic bluefin tuna to the reduction of coal-fired power plant emissions.
"We just see a striking coincidence that the decline in emissions was almost identical to the decline in the mercury concentration in the tuna," he said.
In 2005, there were 619 coal-fired power plant sites in the U.S. By 2015, there were 427, according to the U.S. Energy Information Administration's 'Annual Electric Generator Report'.
In addition to mercury, coal-fired power plants emit carbon dioxide and other greenhouse gases which scientists say contribute to climate change.
Daniel Madigan, who worked on the study as a postdoctoral researcher, said this is a bit of good news to come out of the emissions conversation.
"Maybe one of the best things is that almost every time you look at something like this, it's getting much worse," he said. "Just to see that it's not getting worse at this point is pretty good news. And of course, changing positively is also good news."
The study also shows that we don't have to wait generations to see the results of reduced emissions.
Most Atlantic bluefin tuna is sold in Japan where it is considered a delicacy and can fetch higher prices than when sold in the United States.
The entire study can be found in the December 6, 2016 issue of Environmental Science & Technology. It is titled "Declining Mercury Concentrations in Bluefin Tuna Reflect Reduced Emissions to the North Atlantic Ocean".
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