US Shift Away from Coal Is Saving Tuna From Mercury Contamination, Study Finds

President-elect Donald Trump's stance against climate change is alarming after what appears to be reductions in environmental toxins in the Atlantic bluefin tuna.

Concern for the species began with a professor in New York found excess levels of mercury in a can of tuna that eventually caused a nationwide recall. Since then, tuna consumption has been the source of 40 percent of mercury contamination in the American diet.

This is a growing concern since mercury exposure from all sources can cause cognitive impairment, and affects around 300,000 to 600,000 babies born in the U.S. every year.

A new study now linked the decline of tuna contamination to the reduced mercury emissions in North America. According to Scientific American, this was because of the marketplace shift by power plants away from coal. The latter appears to be the major source of mercury emissions worldwide.

However, the threat toward tuna conservation is real as President-elect Donald Trump is "promising a comeback" for the U.S. coal industry.

The study analyzed tissue samples of about 1,300 Atlantic bluefin tuna taken by commercial fisheries between 2004 and 2012 and found out the levels of mercury concentration dropped by more than 2 percent each year. This resulted in a 19 percent decline in just nine years.

The researchers affirmed that they expected the decline in the amount of mercury entering the atmosphere, but were surprised to see it affected fish as well.

Given that the Atlantic bluefin tuna are big predators, they are suited to accumulate mercury and other contaminants. The study also surprised researchers since mercury lives long in the environment, and mercury from the industrial era still persisted in the deep ocean. Regardless, the bluefin tuna demonstrated that "even a fishery we would have thought had a certain amount of chemical inertia can be cleaned up" provided enough contaminants were removed.

The Atlantic bluefin tuna is highly-prized, especially in countries in Japan. It can be recalled that one such fish went for $118,000 at an auction last year.