Eating seafood can be a healthy way to get important nutrients like protein, healthy fats, vitamins, and minerals. However, some types of saltwater fish contain concerning levels of mercury, PCBs, and other toxins. This article will go over which saltwater fish are best avoided due to safety concerns.
Fish highest in mercury
Mercury is a heavy metal that can build up in fish and shellfish. When humans consume high levels of mercury, it can damage the brain, kidneys, lungs, and other organs. The most common route of mercury exposure in humans is by eating fish contaminated with methylmercury.
In general, larger and longer-lived predatory fish tend to have higher levels of mercury. This is because they consume many smaller fish over their lifespan, accumulating mercury up the food chain.
Here are some saltwater fish highest in mercury that are best avoided, especially for pregnant women, nursing mothers, and young children:
- Tilefish (also called golden bass or golden snapper) from the Gulf of Mexico
- King mackerel
- Shark
- Swordfish
- Marlin
- Orange roughy
- Bigeye tuna
- Ahi tuna (also called yellowfin tuna)
- Bluefin tuna
The FDA and EPA recommend pregnant women, nursing mothers, and children avoid eating the fish above entirely. For the general adult population, they recommend limiting intake to no more than 1 serving per week.
Fish with high PCBs
PCBs (polychlorinated biphenyls) are industrial chemicals that were used in electrical equipment, plastics, insulation, and other products until they were banned in the 1970s. However, PCBs still persist in the environment and accumulate up the food chain in fish and marine mammals.
Long-term PCB exposure is linked to immune system dysfunction, neurological effects, endocrine disruption, and cancer. Here are some saltwater fish with relatively high PCB contamination to limit or avoid:
- Wild salmon from the Great Lakes
- Bluefish
- Striped bass
- Chilean sea bass
- American lobster from the Atlantic coast
To limit your PCB exposure, avoid or limit consumption of the fish above. Opt for wild salmon from Alaska or the Pacific instead, which tend to be lower in PCBs.
Fish prone to ciguatera poisoning
Ciguatera is a type of food poisoning caused by ingesting certain reef fish contaminated with ciguatoxins. Ciguatoxins are odourless, tasteless toxins produced by microscopic algae that accumulate up the food chain in fish.
People who develop ciguatera poisoning may experience nausea, vomiting, and neurological symptoms like tingling fingers and toes. Though rarely fatal, symptoms can persist for weeks, months, or years.
The following tropical and subtropical saltwater fish are most prone to ciguatera poisoning:
- Barracuda
- Red snapper
- Amberjack
- Grouper
- Surgeonfish
- Parrotfish
- Wrasse
- Coral trout
- Moray eel
- Spanish mackerel
Avoid eating the fish above, especially if caught in areas prone to ciguatera, like the Caribbean Sea and Pacific islands. Freezing does not destroy the ciguatoxins, so even fish served at restaurants could pose a risk if from a ciguatoxic area.
How to reduce your risk
To reduce your risk of ingesting excessive mercury, PCBs, ciguatoxins, and other contaminants from saltwater fish:
- Check your local fish advisories. Avoid fish from contaminated water bodies.
- Limit or avoid the high-risk fish listed in this article.
- Eat a variety of fish to avoid overconsuming any one source.
- Purchase sustainably caught or raised fish.
- Limit tuna intake to no more than 1 serving per week if pregnant or breastfeeding.
- Avoid raw or undercooked fish to reduce parasite risk.
Healthier saltwater fish choices
Instead of the high-risk fish listed earlier, here are some better saltwater fish choices:
| Fish | Notes |
|---|---|
| Pollock | Low in mercury and PCBs |
| Tilapia | Raised in environmentally controlled conditions |
| Atlantic mackerel | Low in mercury and high in omega-3s |
| Pacific cod | Low in mercury and PCBs |
| Walleye | Freshwater whitefish low in contaminants |
| Salmon | Wild-caught Alaskan is low in PCBs |
| Sardines | Small fish low on food chain |
| Rainbow trout | Freshwater farmed fish |
| Flounder | Relatively low in mercury |
In addition to the fish above, smaller saltwater fish like anchovies, herring, sardines, and smelt are good choices since they are lower on the food chain and contain less mercury and other contaminants.
Seafood concerns during pregnancy and breastfeeding
Because developing fetuses and infants are especially vulnerable to mercury and other contaminants, pregnant and breastfeeding women need to take extra care.
Here are a few important precautions for pregnant and breastfeeding women:
- Completely avoid shark, swordfish, king mackerel, tilefish, and bigeye tuna.
- Limit white (albacore) tuna to no more than 6 oz per week.
- Limit fish caught locally (in lakes, rivers, etc) to just 1 serving per week due to unknown contaminants.
- Limit oily fish like salmon and trout to just 1-2 servings per week to minimize PCB exposure.
- Choose smaller fish and avoid any raw or undercooked seafood.
Check local advisories about fish safety in your area’s lakes and rivers while pregnant or breastfeeding. While most recommendations focus on mercury, there could also be local concerns about PCBs, dioxins, or other toxins.
Who should be especially cautious
In addition to pregnant and breastfeeding women, here are some other groups that need to practice extra caution regarding fish intake:
- Infants and young children
- Women who may become pregnant
- People who frequently eat sportfish caught from local water bodies
- People who rely heavily on seafood for nutrition
- Individuals with certain medical conditions like:
- Impaired kidney function
- Autoimmune disorders
- Hypertension
- Cardiovascular disease
- Diabetes
Those with medical conditions may be more vulnerable to the effects of mercury and other contaminants. Frequent consumers of locally caught fish or those who eat a lot of seafood should carefully follow local advisories.
Conclusion
While seafood can be healthy, some saltwater fish contain high levels of mercury, PCBs, and other toxins. It’s important to limit or avoid fish known to be high in contaminants like shark, swordfish, king mackerel, tilefish, and bigeye tuna.
Pregnant and breastfeeding women need to practice extra caution. But the general population should also limit intake of high-risk fish and opt for safer choices like salmon, tilapia, trout, pollock, cod, and anchovies.
Checking local fish advisories and following recommended guidelines can help minimize your risk and allow you to safely enjoy the health benefits of seafood.