Mercury
levels in bluefish caught off the U.S. Atlantic coast dropped more than 40
percent over the past four decades thanks to federal restrictions on coal
emissions, according to a new study.
This
is good news not only for bluefish but for the entire predator fish population
in the Mid-Atlantic. And it's better news for people fond of eating the tasty
fish, often served broiled or baked, as it suggests that mercury reductions due
to coal-fired plant emissions crackdowns in North America have quickly led to
less contamination in marine life.
“This
is an important study … this is the type of work that we need to encourage
policy makers to support clean-coal technology,” said Katlin Bowman, a postdoctoral
scholar at the University of California’s Department of Ocean Sciences who was
not involved in the study.
Coal-fired
plants are big mercury contributors to the atmosphere – where most emission
pollution gets dumped – and the ocean, where those pollutants eventually
settle.
That
assumption appears to be wrong, he said.
“What
the EPA decides clearly makes a difference as to how much mercury people
consume,” Barber said.
Coal,
bluefish mercury levels drop in tandem
Barber
and colleagues tested the mercury levels in the muscle of adult bluefish
collected in 2011 off the North Carolina coast and compared it with similar
testing from 1972.
Concentrations
decreased 43 percent. The drop is similar to reductions of mercury observed in
"atmospheric deposition, riverine input, sea water, freshwater lakes and
freshwater fish across northern North America,” Barber and colleagues wrote in
the study published this month in the Environmental Science and Technology
journal.
Five
studies that Barber examined all show a “tight” correlation between the amounts
of mercury emitted from coal plants and concentrations in fish. Nothing, he
said, suggests that "there is not a tight coupling between deposition and
fish.”
Coal
burning is considered the major contributor of mercury in today's environment.
Power plants send mercury into the atmosphere that is then deposited in oceans,
mostly through rainfall.
A report last year that
examined emissions from the top 100 U.S. electric power producers found a 50
percent decrease in mercury emissions from 2000 to 2012.
With
evidence that aquatic wildlife are, at least in part, responding to such
measures, “there is increased incentive to document and predict future changes
in mercury concentrations in marine fish, particularly those of economic value,
” Barber and colleagues wrote.
President
Obama has attempted to further restrict emissions of mercury and other toxics
from coal-fired plants through the Clean Air Act, but the Supreme Court blocked
the ambitious initiative last month.
Barber
and colleagues wrote that increasingly stringent measures on coal plants could
drive mercury levels in fish even lower but cautioned that, since mercury
travels the globe on wind and air currents, such reductions could be
“overwhelmed by a continued increase in mercury emissions from Asia.”
Bowman
also cautioned that, even though bluefish have had steady declines over 40
years, there is still a large quantity of legacy mercury that can be re-emitted
from the environment, so the trend could change.
To
eat or not to eat
Popular
to catch due to their aggressive fight and to eat, bluefish are a migratory
fish and can be found from Maine to Florida in the Atlantic. Recreational
anglers and commercial fleets harvest roughly 13 million pounds and 5 million
pounds a year respectively, said José Montañez, a fishery management specialist
with the Mid-Atlantic Fishery Management Council.
Schools
of fish migrate together in the spring to an area called the Mid-Atlantic
Bight, the shelf waters from Nantucket Shoals off Cape Cod, Massachusetts, then
head south to Cape Hatteras, North Carolina.
They’re
voracious eaters, feeding on a wide variety of ocean creatures.
Fish
high in the marine food chain such as bluefish are considered the major source
of mercury exposure in the United States. Studies have linked pregnant women’s
high mercury consumption in seafood to reduced IQs and memories and other
neurological impacts in their children.
Among
coastal U.S. coastal areas, women along the Atlantic coast were recently shown
to have the highest average
mercury blood levels. Bluefish have long been considered a species
with pretty large mercury loads compared to other commercially caught
fish.
However,
there are benefits to eating fish. Research has shown that fish consumption
provides vital nutrients, Omega-3 fatty acids and protein, for fetal brain
growth, and that children's IQs increase when their mothers had eaten
low-mercury fish.
The
study could “potentially impact demand for the product [bluefish],” Montañez
said.
Health
officials have long struggled with how to balance the benefits and downsides of
eating fish.
“It’s
really difficult to tell. We all judge risk benefit info differently. I know
people that will not feed a single bluefish to their kids,” Montañez said.
“Then I know people who smoke it and eat it all year long and they’re both
aware of the potential problem with contaminants.”
Last
summer the U.S. EPA and
FDA made major changes in their advice to pregnant and
breastfeeding women by recommending consumption of at least 8 ounces of
low-mercury fish per week.
Bowman
said a good next step would be to examine other fish species to ensure that the
decline is connected to decreasing mercury emissions and not driven by some
change in the physiology or feeding patterns of bluefish.
For
questions or feedback about this piece, contact Brian Bienkowski at bbienkowski@ehn.org.
