- 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.
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 (NRDC) recommends prioritizing low-mercury fish like salmon, trout, and sardines. Most people can safely eat these options up to six times a month.
On the other hand, high-mercury fish like albacore tuna, sea bass, and grouper should be eaten sparingly—no more than 3 times monthly. And some fish, like Gulf of Mexico tilefish and swordfish, are best avoided altogether.
Credit: Visual Capitalist
