Mercury is a heavy metal that accumulates in certain fish species, and exposure to high levels can have negative health effects. Both salmon and tuna can contain mercury, but tuna typically has higher mercury levels than salmon.
Quick Answers
– Salmon generally has lower mercury levels than tuna. This is because tuna is larger and lives longer than salmon, so mercury accumulates to higher levels.
– Wild salmon tends to have lower mercury levels than farmed salmon. Wild salmon eat other organisms lower on the food chain that contain less mercury.
– Certain tuna species like bigeye and bluefin tuna have particularly high mercury levels. Albacore (white) tuna has lower mercury than these species.
– Salmon and tuna are both nutritious fish rich in omega-3s. Eating 8-12 ounces of low mercury fish like salmon per week offers health benefits and is considered safe.
Why Tuna Accumulates More Mercury
Tuna contain more mercury than salmon for a few key reasons:
Tuna are larger fish
– Tuna can grow over 6 feet long and weigh hundreds of pounds. Larger and older fish accumulate more methylmercury.
– Salmon rarely exceed 100 pounds in weight. Their smaller body size limits mercury accumulation.
Tuna live longer
– Tuna are long-lived fish that can survive over 10 years. Their longer lifespans allow more time to accumulate mercury.
– Salmon only live 4-5 years, which restricts their mercury uptake.
Tuna eat other large fish
– Tuna are apex ocean predators that consume other large, contaminated fish like swordfish, tilefish, and shark. This transfers dietary mercury up the food chain.
– Salmon eat smaller fish, crustaceans, and insects much lower on the food chain with less mercury exposure.
Mercury Levels in Salmon vs. Tuna
Here is a comparison of the typical mercury levels found in salmon versus tuna:
| Fish | Mercury (ppm) |
|---|---|
| Atlantic salmon (farmed) | 0.01 |
| Coho salmon (wild) | 0.01 |
| Albacore tuna | 0.32 |
| Yellowfin tuna | 0.31 |
| Bigeye tuna | 0.85 |
– Farmed Atlantic salmon and wild Coho salmon have nearly identical low mercury levels around 0.01 ppm.
– Albacore tuna has about 32 times more mercury than salmon. Yellowfin and bigeye tuna are even higher.
– Wild salmon has less mercury than farmed since they eat lower on the food chain.
So both lab testing data and the biology of tuna confirm they contain significantly more mercury than salmon.
Healthiest Fish Choices
To get the benefits of omega-3s while limiting mercury risk, these are good fish choices:
– Salmon (wild Pacific salmon is best)
– Sardines
– Anchovies
– Herring
– Rainbow trout
– Atlantic mackerel
Limit tuna intake, especially higher mercury bigeye and bluefin tuna. Albacore canned white tuna has lower mercury levels if consumed in moderation.
The FDA/EPA recommend eating 8-12 ounces (2 average meals) of low mercury fish per week. This amount is considered safe for most adults and provides essential omega-3 fatty acids for heart and brain health. Children and pregnant women should eat less due to greater mercury sensitivity.
Conclusion
In summary, salmon contains significantly less mercury than tuna due to its smaller size, shorter lifespan, and lower position on the food chain. Wild salmon has lower mercury still compared to farmed. To safely get the benefits of fish, choose salmon, sardines, herring and other low mercury varieties according to dietary recommendations. Limit intake of large predatory fish like tuna that accumulate higher mercury levels. Consuming a variety of fish can support health while avoiding excessive mercury exposure.