Is salmon high in mercury compared to other commonly consumed fish like tuna, cod, and shellfish (shrimp, crab, lobster)? I’m trying to make informed dietary choices, particularly regarding mercury exposure from seafood. I understand that larger, predatory fish tend to have higher mercury levels, but I’m unsure where salmon falls on that spectrum. Can you provide a comparison and perhaps explain why some types of salmon might have higher mercury levels than others (e.g., wild-caught vs. farmed, different salmon species)?

Answer

Salmon generally has low to moderate levels of mercury compared to many other fish. Mercury levels in fish vary greatly depending on the species, their diet, age, and location. Larger, predatory fish that live longer tend to accumulate more mercury.

Here’s a more detailed breakdown:

• FDA/EPA Guidelines: The U.S. Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) provide guidelines on fish consumption based on mercury levels. They categorize fish into groups based on their average mercury content.

• Salmon’s Ranking: Salmon is typically classified in the "Best Choices" or "Good Choices" categories, meaning it’s recommended for frequent consumption (2-3 servings per week for adults and children).

• Fish with Higher Mercury: Fish with significantly higher mercury levels include:

  • Swordfish
  • Shark
  • Tilefish (from the Gulf of Mexico)
  • King Mackerel
  • Bigeye Tuna
  • Marlin
  • Orange Roughy

• Fish with Similar or Lower Mercury: Fish with mercury levels similar to or lower than salmon include:

  • Shrimp
  • Canned Light Tuna
  • Cod
  • Catfish
  • Pollock
  • Sardines

• Wild vs. Farmed: The mercury content in wild salmon and farmed salmon is generally similar and considered low.

• Type of Salmon: While mercury levels in salmon are generally low, slight variations can occur between different species of salmon. However, these differences are usually not significant enough to drastically change consumption recommendations.

• Factors Influencing Mercury Levels in Fish:
  • Diet: Predatory fish that consume other fish accumulate more mercury.
  • Age: Older fish have had more time to accumulate mercury.
  • Size: Larger fish tend to have higher mercury levels.
  • Location: Mercury levels in the water and sediment can vary depending on the location, impacting mercury levels in fish.