Seafood lovers have a lot of concerns: Wild-caught or farm-raised fish? Sustainably harvested or whatever is fresh? High mercury levels? The good news is that for most adults—save for those pregnant or nursing—a recent Harvard School of Public Health study found that benefits of eating fish, particularly those rich with omega-3 fatty acids, outweigh risks from contaminants such as mercury often found in them. The bad news: We’re eating fish nearly out of existence, and major stocks could collapse by mid-century if nations don’t curtail the harvest. Advocacy groups offer seafood guides to help buyers make informed decisions about fish consumption. Though lists change from year to year and vary by region, a few species high in omega-3s and low in contaminants come from well-managed fisheries and tend to make the grade across the board.
Choose Safe, Sustainable Fish
• Wild Alaska salmon
• Canned pink or sockeye salmon
• Anchovies
• Sardines
• Alaska sablefish (black cod)
• Atlantic herring
• Atlantic mackerel
• Farmed oysters
Avoid High-mercury Fish
• Tilefish (golden bass)
• King mackerel
• Shark
• Swordfish
• Freshwater sport fish caught in contaminated waters
Not All Fish Are Created Equal
While there are a few species to avoid, such as tilefish, shark, king mackerel, swordfish, and contaminated sport fish, eating seafood is generally good for you. Mercury poisoning, however, can be deadly, and mercury contamination can lead to a host of neurological problems.
A fish’s mercury level depends on a number of factors, including where the fish lives, how old it is, how big it is, and what it eats. Mercury travels up the food chain, so fish that eat other fish are more likely to be contaminated. Mercury levels accumulate over time, so older fish are more likely to have larger concentrations of mercury than younger members of the same species. That means smaller aquatic species (shrimp, scallops, tilapia) are safer bets to guard against contamination. Anchovies and sardines, being small and short-lived, also have low mercury levels. Large, predatory fish (large tuna, sharks, swordfish) contain higher levels of mercury. In fact, fish at the top of the food chain can contain mercury levels that are 10,000 to 100,000 times higher than those of their environments. This helps explain why sharks are on the list of high-mercury foods and wild salmon are not.
While the Harvard study stressed that the benefits of eating fish outweigh the risks, note that—in addition to pregnant and nursing women—small children and women of childbearing age should also be careful to avoid contaminated fish.
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