Experts warn of Mercury levels in Gulf

The warnings about mercury levels in certain types of fish don’t keep Susan Armstrong up at night.

Armstrong, a Port Mansfield resident who enjoys sport fishing, eats a variety of fish several times a week — trout, redfish, red snapper, grouper. The only fish she rarely eats is king mackerel, a species that the Texas Department of State Health Services has warned contains high levels of mercury.

“Eating fish hasn’t hurt me yet,” said Armstrong, who was shopping for crabmeat at a Port Isabel fish market Wednesday afternoon. “I’m not that concerned.”

According to state and federal agencies, though, the amounts of mercury in certain fish caught in the Gulf of Mexico and the Rio Grande could be cause for concern.

A decade ago, the state’s health department issued a consumption advisory on king mackerel caught in the Gulf, cautioning people to minimize their intake of the large fish because of mercury levels. The advisory continues to stand today.

The Environmental Protection Agency also has advised that women of childbearing age, pregnant women and young children avoid eating swordfish, shark and tilefish, which all contain high mercury levels. All of these species make periodic appearances in the Gulf.

“The concern is mainly for pregnant women, childbearing women and young children,” said Dr. Brian Smith, regional director of the Texas Department of State Health Services’ Region 11, which includes the Rio Grande Valley.

Fetuses exposed to high mercury levels can suffer extreme damage to their nervous systems, and might develop hearing loss or learning disabilities, according to the March of Dimes. Mercury also can damage the nervous system, lungs, kidneys and vision of vulnerable adults and children.

MERCURY IN THE GULF

Nearly all types of fish contain some amount of mercury. But it’s the fish at the top of the food chain that have the highest levels, said Pam Baker, regional director for Environmental Defense’s oceans program. Mercury accumulates in fish tissue and the levels grow as the fish grows, she said.

“The mercury doesn’t dissipate over time,” Baker said. “And each time a fish eats another fish, the fish takes on that mercury load too.”

In the Gulf, the types of fish most popular with tourists are smaller than king mackerel or swordfish and therefore lower in mercury — fish like red snapper, dolphin fish and wahoo, for example, said Bryan Ray, owner of South Padre Island-based Master Plan Charters. Several times a week, Ray takes tourists out into the Gulf to fish.

According to the U.S. Food and Drug Administration, red snapper, dolphin fish and wahoo have moderate to low mercury levels.

Tourists occasionally catch larger fish like shark or king mackerel, and that’s when Ray will mention mercury.

“I tell them the smaller king mackerels are much better to eat than the large ones,” he said.

The demand isn’t very high among tourists for fish that historically contain high amounts of mercury. That might be because of health concerns, or just because those fish are harder to catch, Ray said. Kings are more elusive than red snapper, swordfish only make limited visits to the southern Gulf and tilefish are found only in the deep sea, he said.

“King mackerel used to be big business in the 70s and 80s, but we’ve since turned people toward red snapper,” Ray said. “You literally could catch snapper every day of the year Â… and people just want to catch a fish — any fish. You could fish all day for king mackerel and come back with nothing.”

MERCURY IN THE RIO GRANDE

Mercury levels also are “elevated” in the Rio Grande below Falcon Dam, said Wayne Belzer, manager of the Texas Clean Rivers Program, part of the U.S. Section of the International Boundary and Water Commission. It’s a trend they’ll be studying further, Belzer said.

“We don’t see this impairment anywhere else but in this section of the Rio Grande,” he said.

Belzer said he thinks that ocean waters mingling with the Rio Grande at its mouth could be influencing mercury levels in the river.

“We’re not sure of the reason Â… but it could be from the ocean,” he said.

Fish found in the Rio Grande include catfish and carp.

The Department of State Health Services currently has no fish-consumption advisories or bans for fish caught in the Rio Grande.

Mercury levels seem to be building over time in the river, Belzer said. So consumption advisories might come out in the future.

“It’s become an issue just in the last few years,” he said.

SOURCES OF MERCURY

Most of the mercury released into the environment come from manmade sources like coal plants, according to DSHS. Mercury is a byproduct of burning fossil fuels or solid waste, and also results from mining, cement production and other industrial activities.

In addition, mercury can make its way to the soil courtesy of old batteries and fluorescent bulbs in landfills, fertilizer and fungicides.

Eventually, through rain and runoff, the mercury arrives in the sea, rivers and lakes, said Baker of Environmental Defense.

Valley residents could help stop the flow of mercury into the Gulf and Rio Grande by recycling batteries and other mercury-containing materials, said Smith of DSHS.

“The best thing is to take some personal responsibility,” he said.