But his deterioration continued for months, and as doctor after doctor shrugged their shoulders at his symptoms, my dad became increasingly worried as to what it all meant. The headaches, body aches, fatigue and anxiety weren’t going away, so as the rest of us rolled our eyes behind his back, he began to research his symptoms in earnest. Finally, it was my mother who, after countless blood tests, EKGs and CAT scans, grew wise to the one idiosyncrasy in an otherwise healthy lifestyle: the 1 to 2 pounds of striped bass my dad was eating with abandon almost every day.
    Having grown up fishing and sea mossing on Massachusetts’ South Shore, fish had always been a staple in my dad’s diet. And as he aged and began to consider the nutritional content of his meals more carefully, he gravitated toward fish for its “brain food” reputation and widely lauded nutritional qualities. After a heart scare, he gave up red meat almost entirely and based his diet on eating one or two meals of readily available striped bass per day. The basic rational behind his reasoning wasn’t wrong, but he had failed to take into consideration a serious risk that has only recently come to light: mercury poisoning.
    The Environmental Protection Agency has issued a “reference dose” for how much fish a person can safely consume without experiencing any negative effects due to mercury. For a 180-pound adult, the reference dose suggests limiting striped bass to 9 ounces a week. My dad was eating at least 25 times that each week, for months on end. Not only that, he was also consuming the skin and enjoyed picking the skull clean, including the eyes and brain, places where mercury may be concentrated.
    It took months of total fish-abstention for my dad to begin feeling normal and healthy again, and to this day, he remains mercury-shy – but not to the extent that he’ll never eat fish again. On the contrary, he’s just far wiser than before, and he remains very sensitive to any mercury increase in his body. Sure, he’ll eat a small portion of striped bass and maybe the occasional tuna steak, but only very rarely – and he avoids the brains entirely. For the most part, when he eats seafood he sticks to Alaskan salmon, clams, and other lower-mercury choices.
    As part of the fishing community, we’re all aware of rumors about mercury poisoning and fish consumption. We’ve heard that certain species of fish, such as Spanish mackerel, swordfish, tilefish, shark, bluefish and tuna harbor more of a mercury risk than others. Most pregnant women avoid eating fish entirely. But just how great is the risk?
    Maybe these thoughts cross your mind when you’re eating a fresh tuna steak, or maybe you keep these warnings in mind when you’re at the fish market. But the facts about the risks of mercury in seafood remain vague, so how do we balance those risks with the benefits of seafood? When my dad finally brought his concerns to his doctor, he was met with a blank stare: his doctor was totally unaware of mercury risks. Guidelines set by the EPA and the Food and Drug Administration have provided a generalized blueprint for fish consumption since 2001, but more recent studies have cast doubt on conventional wisdom and contradict the caution urged by these organizations. So, from a real-life perspective, how much fish is too much?

It’s Not That Silver Stuff in My Thermometer, Right?
    When we talk about mercury in fish, we are referring to inorganic mercury that is deposited into water both naturally and by industrial pollution. Anaerobic organisms that live in aquatic systems then convert it into methylmercury. Tiny aquatic plants and animals that absorb this state of methylmercury are not capable of eliminating it from their systems, and it begins to accumulate. In a process called biomagnification, the concentration of mercury increases in accordance with each level of the food chain. For example, bacteria is eaten by plankton is eaten by herbivorous fish is eaten by carnivorous fish is eaten by a big, nasty predator. As increasingly larger organisms consume smaller organisms, the mercury in their own systems is magnified.
    Ultimately, the concentration of mercury levels in any one fish depends on a number of factors – the fish species, its diet, age, size and water in which it lives – though as a general rule, large, longer-lived fish have a greater accumulation of mercury than smaller fish. Because seafood constitutes the main source of methylmercury exposure to humans, we are being warned with increasing frequency to limit our intake of fish, particularly such larger species as shark, tilefish, swordfish and Spanish mackerel.
    When ingested by humans, methylmercury is quickly absorbed by the gastrointestinal tract. In the human body, it behaves similarly to methionine, one of the human body’s essential amino acids. Because of this mimicry, methylmercury is not easily eliminated from the body, and is allowed access to all parts of the body, including the brain and across the placenta. The human nervous system is highly sensitive to all forms of mercury, and mercury accumulation has been linked to cardiovascular disease in adults and potential autoimmune problems, although it has not been linked with any specific cardiovascular or autoimmune disease.
    The detrimental effects of accumulated methylmercury in the human body are initially manifested in the brain and nervous system. Symptoms of mercury poisoning include: hand tremors (progressing to other parts of the body); muscular weakness and twitching; numbness in the fingers and toes; slurred speech; memory loss and decreased cognitive functioning; irritability, extreme nervousness, shyness and loss of confidence; fatigue; headaches; hallucinations and hearing loss.

So Limit Your Fish Intake…
    It is generally accepted that methylmercury is toxic can adversely affect a child’s brain development if it is exposed during pregnancy. But questions remain as to what levels of mercury start posing a threat to both children and adults. Both the FDA and the EPA have acknowledged the excellent nutritional benefits of eating fish and conceded that mercury poisoning in healthy adults is usually not a problem – usually. But what about a fishing community where seafood is a primary source of food?
    In 2001, the FDA and EPA created a set of guidelines to help consumers make wiser choices regarding intake of higher-mercury fish. FDA toxicologists created an “action level” for the mercury content in commercial fish at 1 part per million. Once the mercury content reaches this level, the FDA is allowed to take legal action and prohibit its sale. This raises awareness about fish with the highest mercury content: swordfish, shark, Spanish mackerel, tilefish and, occasionally, tuna. The FDA has posted its 2004 mercury advice at www.cfsan.fda.gov/~dms/admehg3.html. The EPA has also created a calculation for a “reference dose” that sets a limit on the amount of mercury that can be safely consumed without risking any adverse effects. Basically, the reference dose uses your weight and the fish species to determine how much you can eat each week. Check out the EPA’s website on mercury at www.epa.gov/mercury.
    O.K… so how does this translate to reality, and what does this mean for the average Northeastern fisherman? According to both these guidelines, it pretty much depends on the fish you are eating. The FDA and EPA guidelines suggest minimizing your intake of the four aforementioned species because of their respective mercury contents, but many of the more popular New England fish have only trace amounts of mercury. For a 180-pound adult, the EPA invites you to eat up to 3 pounds of flounder per week; 4 pounds of haddock; or 2 ½ pounds of scallops. Being a scallop fan myself, that sounds pretty good.
    But when you take the larger, long-lived ocean fish into the equation, the process gets trickier. For the same 180-pound adult, the EPA becomes a lot stricter: 9 ounces of striped bass, and 6 ounces for bluefish, yellowfin and albacore tuna. You can see what the EPA reference dose holds for you by visiting www.gotmercury.org.
    When considering these guidelines, however, it’s wise to bear in mind that these levels were calculated to set a limit 10 times lower than levels that potentially begin to show negative effects. The FDA has acknowledged that these guidelines err on the side of caution to provide the safest possible levels for those most at risk – youths and unborn children – and to account for a variety of additional factors: incomplete information, individual sensitivity to mercury, etc. This is not unusual, and the head of the FDA’s Office of Food and Safety suggests using the EPA’s threshold more as a guideline than a set rule.
    For example, when the EPA recommends eating no more than 9 ounces of striped bass a week, the amount that has been determined to carry a potential risk is closer to 90 ounces, or roughly 5 ½ pounds. Thus, a 180-pound adult who eats 2 pounds of striped bass a week would technically exceed the EPA reference dose by 250 percent, but would still be well below the range at which mercury might become a problem. The EPA reference dose for yellowfin tuna is 6 ounces, but potential negative effects have only been associated with eating about 4 pounds. If you were to throw caution to the wind, ignoring these guidelines and eating that fresh swordfish steak, you would still be well beneath the harmful methylmercury levels.
    In 2004, the FDA and the EPA released a revised report on fish consumption, What You Need to Know About Mercury in Fish and Shellfish, that was directed specifically toward pregnant women and/or children. Although this report confirmed that fish is indeed an integral part of a healthy, low-fat diet, it also stipulated that methylmercury is damaging to a child’s developing nervous system. In effect, certain guidelines for pregnant women advised them to 1.) avoid shark, swordfish, king mackerel, and tilefish entirely 2.) eat up to 2 meals a week (12 ounces) of lower-mercury fish and shellfish and 3.) always refer to local advisories regarding locally caught fish.

… But Not So Fast
Yet in the past year, groundbreaking new research has emerged that appears to fly in the face of these conclusions. The vast bulk of controversy rests on a study led by Joseph R Hibbeln, a researcher at the National Institute of Alcohol Abuse and Alcoholism, for The Lancet, one of Britain’s premier scientific journals. After observing roughly 15,000 babies and their mothers, the study determined that reducing fish intake during pregnancy does not protect against mercury poisoning. Instead, children whose mothers ate less than 12 ounces of fish per week (the EPA and FDA’s cutoff for fish consumption for pregnant women) ran an increased risk of having the lowest-quartile verbal IQs.
    The study decided that optimum neural development relies heavily on certain nutrients, one of which is an essential omega-3 fatty acid found in seafood. The lower the seafood consumption during pregnancy, the lower the levels of “prosocial behavior,” fine motor, communication and social development scores. Ultimately, the authors concluded that loss of essential nutrients found in fish outweighs the potential harm caused by ingested methylmercury. As such, could the current EPA guidelines for pregnant women actually be detrimental to the development of the child?
    So again, how does this affect the Northeastern fisherman? As I stated above, federal mercury guidelines were established to provide the safest levels of mercury for the most vulnerable members of society. When these recent studies claim that eating more fish is actually beneficial for children and development, the same is indicated for adults: fish really is a brain food, and eating more than the guidelines designate isn’t harmful. Just be wary when eating the higher-mercury fish!
    Several additional studies have been conducted in recent years to find an effective balance between fish health risks and benefits. In general, these studies conclude that seafood is one of the single healthiest foods available, and that the average person should actually be eating more. Although some fish do contain higher levels of mercury, the omega-3 acids found in fish also have been credited with protecting against Alzheimer’s disease, arthritis, and many other conditions, including stroke.
    In 2006, the Institute of Medicine released a study that confirmed that eating fish significantly reduces the risk of heart attack and heart disease. In the Journal of the American Medical Association, researchers at Harvard University concluded that the benefits of eating fish far outweigh the potential risks of methylmercury poisoning for the adult population. Both studies encouraged increasing the amount of fish consumed, but urged consumers to make wise choices when eating the longer-lived species. For women of childbearing age, the studies recommended modifying or varying fish intake and avoiding the aforementioned species.

Have Your Fish and Eat It, Too
    So where does this leave us? Common sense dictates a pretty simple strategy for navigating all this information: continue eating your fish, but be prudent when eating the largest predators. Don’t eat as much as my dad did! Fish is great for you. It is a lower-fat, heart-healthy food choice that can offer incredible nutritional benefits. Taking this into consideration, the current movement to make mercury warnings mandatory may seem not only like overkill, but also a pretty bad health decision. If mercury warnings are posted throughout supermarkets, they will likely be misinterpreted and misunderstood by consumers, ultimately stigmatizing fish and causing people to avoid it. Both the FDA and the EPA acknowledge that is not a good thing, and that consumption advice is unnecessary for the most popular seafood species: canned tuna, shrimp, pollock, salmon, cod, catfish, clams, flatfish, crabs and scallops. Not only is it unnecessary, but you will be missing out on some of the healthiest food available. The responsible advice is not to avoid any kind of fish entirely, but to eat it intelligently. In other words, the wise Northeastern fisherman can have the best of both worlds, eating plenty of heart-healthy fish without putting himself at risk.