Catch and Release?

It’s one of the iconic images of the good life in Minnesota: a beaming governor holding a meaty walleye, or possibly a northern pike, on his line. It’s the fishing opener photo op that signals the real start of summer, when Minnesotans can finally drop their lines in open water and fill their coolers with the bounty our 10,000 lakes have to offer.

Back in the day, there was only one question that concerned anyone about fish: Beer-battered, butter-fried, or broiled? Now when people ask Tim Lauer about their catch, their concerns often go beyond matters of taste. They wonder if they should be eating fish at all. 

“Mercury is always the big concern,” says Lauer, general manager of Coastal Seafoods in the Twin Cities. Not only does he have to walk customers through the messier aspects of cleaning a fish, but often through the state health department’s determination that most fish caught in most of Minnesota’s lakes and rivers are safe for most people to eat.

Lauer might point customers toward a host of studies showing that eating fish of all kinds is important for good health—that eating fish may cut the risk of heart disease, lower blood pressure, and even reduce the effects of depression. He might add that no less an authority than the Mayo Clinic says that most Americans aren’t getting enough fish in their diets. The three ounces of fish the average American eats every week adds up to less than ten pounds per person a year—a flash in the pan compared with the fifty pounds of chicken and sixty-four pounds of beef Americans eat on average annually.

Yet, in spite of the relatively small space it takes on our dinner plates, fish has become a major focus for anxieties about the food we eat, the environment we’ve compromised, and the intersection of the two. The “brain food” that our mothers pushed on us without a thought has become a kind of brain-teaser for the current generation confused by headlines about pollutants, the politics of farm-raised fish versus wild-caught, and federal guidelines that tell us to eat more fish—but not too much.

Little wonder a recent survey conducted by NPD, a New York market research firm, found that 67 percent of us are aware and concerned about the mercury content in fish and seafood—though we have little knowledge of which fish we should actually be concerned about. Only one in five consumers was able to identify the fish highest in mercury for a study conducted last summer by the Center for Science in the Public Interest, a nonprofit food-safety advocacy group headquartered in Washington, D.C. The correct answers: swordfish, shark, king mackerel, and tilefish. Instead, 21 percent of those surveyed picked salmon as a serious offender. In fact, most salmon contains relatively low levels of mercury, while it’s loaded with the omega-3 fatty acids that researchers say we need.

“Consumers are definitely confused,” says Pat McCann, a research scientist with the Minnesota Department of Health and coordinator of its fish advisory program. “But our message has been consistent. Most fish is good for you. The benefits of eating most fish still far outweigh the risks.”The historic headwaters of early research on mercury pollution and fish is right here on the Mississippi River, which was tested in 1969 and found to be deserving of its nickname, the Big Muddy.

“The first testing of mercury in fish found that there were high levels in the Mississippi, and people thought, ‘That makes sense—it’s polluted,’ ” says Daniel Engstrom, director of the St. Croix Watershed Research Center at the Science Museum of Minnesota. Far more startling at the time was the discovery that some of the major lakes in Voyageurs National Park—presumably as pristine as any waters in the world—were similarly sullied.

As scientists have since learned, most of the mercury that contaminates fish comes from human sources—coal combustion, mining, manufacturing, and the burning of products that contain mercury—and those emissions are carried by the wind and deposited on land and water. Micro-organisms in the water can convert the mercury into a more toxic form—methylmercury—which is, in turn, absorbed by other organisms, then eaten by small fish and then by larger predators, each link in the food chain absorbing potentially higher concentrations of the toxin in a process known as bioaccumulation. A powerful neurotoxin, methylmercury is especially harmful to brain development in children. Elevated mercury levels in wildlife have also been linked to motor skill impairment, hormonal changes, and reduced reproductive success. One study estimates that 8 percent of U.S. women of childbearing age have blood mercury levels in excess of what the Environmental Protection Agency deems safe.

By 1975, state health officials had begun issuing the now familiar fish consumption advisories that go something like this: Choose pan fish such as sunnies, crappies, and perch, which are less likely to have built up high levels of mercury. Go for the smaller game fish and trim away skin and belly fat, where PCBs (synthetic oils that were banned in 1976, but decompose slowly) can build up. Because there’s no way to clean or cook a fish to eliminate the mercury content, limit meals of larger fish such as walleye, bass, and lake trout to one meal a week for men and once a month for children or women of childbearing age. Any fish large and mature enough to win a contest is probably better mounted on a plaque than served on a plate.

Anglers interested in the fish stock of a particular lake can also turn to the Lake Finder feature created by the MDH and the Department of Natural Resources, analyzing more than 1,000 popular lakes and rivers. There you may learn that women of childbearing age and children should limit their meals of smallmouth bass from the Lake of the Woods to once a month, though they can eat unlimited amounts of sunfish caught from the high-traffic waters of Lake Minnetonka. These readings can seem counterintuitive, but the fact is, the complex balance of wetlands, bacteria, and watershed makes some of the cleanest lakes in the state especially efficient at converting mercury into methylmercury.

While mercury remains the top health concern, the state monitors other pollutants as well. In April, the MDH issued a fish consumption advisory for Lake Calhoun and parts of the Mississippi south of Minneapolis after the chemical perfluorooctane sulfonate—a chemical once used in 3M’s Scotchgard and other products—was found in fish taken from those waters. Now anglers are advised to limit meals of bluegill caught in Lake Calhoun and its connected chain of lakes—Brownie, Cedar, Lake of the Isles, and Harriet—to just once a month.

Minnesota is a national leader in fish-monitoring programs, in part because we have so many lakes and rivers. In 1994, the MDH became the nation’s first health department to integrate consumption advisories for fish caught in the state with warnings about commercial fish caught elsewhere. “MDH felt that all sources of methylmercury exposure should be considered when making choices about which fish to eat and how often,” McCann explains. “We also wanted to inform women who were eating Minnesota sport fish that it’s not necessarily safer to substitute commercially available fish.”

The FDA followed suit a few years later with a fish advisory for pregnant women, which it reissued in 2001 and again in 2004, in partnership with the EPA. Some observers wonder if the frequent headlines reassuring consumers about “fish safety” and reissued guidelines explaining the difference between canned light tuna and albacore may have actually created more confusion than they resolved.

Still, the health benefits of fish have kept rising to the surface.

Last fall, the Harvard School of Public Health reviewed existing studies and declared that eating two portions of fish a week—for example, three ounces of farmed salmon or six ounces of mackerel—lowers the risk of death from heart disease by a third.

In February, The Lancet, a British medical journal, compared the children of 8,000 women who ate more than twelve ounces of fish and seafood a week during their pregnancies with kids whose moms didn’t eat as much fish. According to that study, the children with fish-favoring mums scored higher on development, behavior, and verbal IQ scores between toddlerhood and the age of eight than the other group. (While some commercial fish lobby groups have hailed this as a sign that mercury warnings for pregnant women are all wet, it’s worth noting that the women in the study ate the low-mercury fish recommended by such guidelines. The study also relied on mothers to self-report their children’s intelligence and social skills—assessments that ought to be taken with a grain of sea salt, if not a squeeze of lemon.)

In March, researchers at the University of Pittsburgh’s medical school reported that the omega-3 fatty acid DHA found in some fish boosts gray matter in the mood centers of the brain, where depressed people tend to have the least gray matter. Though researchers are still cautious about claiming that fish can fight depression, previous research has shown that high levels of DHA can improve brain function, mood, and memory, and may even cut the risk of developing dementia by half. 

Such findings may explain why the people who have really gone to school on the topic still favor fish. Daniel Engstrom was part of the international team of mercury scientists that recently released the so-called “Madison Declaration,” in the Swedish science journal Ambio, calling for a worldwide general warning about mercury in fish, especially for children and women of childbearing age. But far from being afraid of eating fish, Engstrom believes that being cautious about our catch might prove healthy for us in other ways.

“Our concerns about fish should be a kind of wake-up call that what we have set into motion has repercussions in the food we can eat,” he says, pointing out that fish isn’t the only food that’s exposed to pollution. “We need to be aware of what’s happening out there so we can begin to change it.”

And what’s his personal preference for that walleye on the line?

“Broiled,” he says. “Definitely broiled.”

Laura Billings’s health reporting has appeared in Self, Health, Cooking Light, and Parenting. Her Fit for Life column appears monthly in Mpls.St.Paul Magazine.