Visualized: How Much Mercury is in the Fish You Eat?
Description
How Much Mercury is in the Fish You Eat?
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- Low-mercury seafood options include scallops, clams, shrimp, and salmon, all with less than 0.02 ppm.
- Top predators like swordfish, shark, and Gulf of Mexico tilefish have the highest mercury levels, some over 1.0 ppm.
- Experts recommend eating high-mercury fish no more than 3 times a month, or avoiding them entirely.
Mercury in fish is a well-documented health concern, especially for pregnant individuals and young children.
The FDA tracks mercury concentrations in commercial seafood, helping consumers make informed choices. The visualization by Julie Peasley summarizes these levels beautifully, grouping fish by mercury content and recommended servings per month.
| Fish | Mercury Concentration PPM (rounded to nearest hundredth for most species) |
|---|---|
| Scallop | 0.003 |
| Clam | 0.009 |
| Shrimp | 0.009 |
| Oyster | 0.01 |
| Sardine | 0.01 |
| Tilapia | 0.01 |
| Salmon (Canned) | 0.01 |
| Anchovy | 0.02 |
| Salmon (Fresh/Frozen) | 0.02 |
| Catfish | 0.02 |
| Squid | 0.02 |
| Pollock | 0.03 |
| Crawfish | 0.03 |
| Shad | 0.04 |
| Mullet | 0.05 |
| Whiting | 0.05 |
| Atlantic Haddock | 0.06 |
| Butterfish | 0.06 |
| Flatfish (Flounder, Plaice, Sole) | 0.06 |
| North Atlantic Mackerel | 0.06 |
| Atlantic Croaker | 0.07 |
| Crab (Blue, King, Snow) | 0.07 |
| Freshwater Trout | 0.07 |
| Hake | 0.08 |
| Herring | 0.08 |
| Jacksmelt | 0.09 |
| Pacific Chub Mackerel | 0.09 |
| Sheepshead | 0.09 |
| Whitefish | 0.09 |
| Cod* | 0.11 |
| Northern/American Lobster | 0.11 |
| Ocean Perch | 0.12 |
| Tuna-Canned Light | 0.13 |
| Atlantic Tilefish | 0.14 |
| Tuna-Skipjack | 0.14 |
| Freshwater Perch | 0.15 |
| Monkfish | 0.16 |
| Bass (Black, Striped) | 0.17 |
| Snapper | 0.17 |
| Mahi Mahi | 0.18 |
| South Atlantic Spanish Mackerel | 0.18 |
| Weakfish (Sea Trout) | 0.24 |
| Halibut | 0.25 |
| Pacific White Croaker | 0.29 |
| Albacore Tuna-Canned | 0.35 |
| Chilean Sea Bass | 0.35 |
| Yellowfin Tuna (Fresh/Frozen) | 0.35 |
| Albacore Tuna | 0.36 |
| Sablefish (Black Cod) | 0.36 |
| Bluefish | 0.37 |
| Grouper | 0.45 |
| Gulf of Mexico Spanish Mackerel | 0.45 |
| Marlin | 0.49 |
| Orange Roughy | 0.57 |
| Bigeye Tuna | 0.69 |
| King Mackerel | 0.73 |
| Shark | 0.98 |
| Swordfish | 1 |
| Gulf of Mexico Tilefish | 1.12 |
Seafood like scallops, clams, and sardines fall into the “low” mercury category, while swordfish and shark top the “avoid” list due to concentrations near or above 1.0 ppm.
Why Mercury in Fish Matters
Mercury, especially in its organic form methylmercury, is a potent neurotoxin. It can impair brain development in fetuses and young children and has been linked to cognitive decline and cardiovascular issues in adults. According to the EPA, fish consumption is the primary source of mercury exposure for most people.
The harm isn’t just theoretical. High intake of mercury-laden fish can lead to mercury poisoning, with symptoms like muscle weakness, vision problems, and memory loss.
How Does Mercury End Up in Fish?
Mercury in oceans originates largely from industrial pollution, especially coal-fired power plants and mining operations. This mercury settles into waterways and is converted by microbes into methylmercury, which accumulates in aquatic organisms.
As smaller fish are eaten by larger predators, mercury moves up the food chain in a process known as biomagnification. This explains why large species like swordfish, marlin, and shark contain the highest concentrations. Simply put, the longer a fish lives and the more it eats, the more mercury it accumulates.
Smart Seafood Choices
The Natural Resources Defense Council (<a href="h
United States
