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Does the mercury content for different species of fish vary over time and location?

It's easy to find estimates of mercury content in fish, but most of the data I can find from sources like FDA have 10+ year old data, and some data is as old as the 1970s. https://www.fda.gov/food/metals-and-your-food/mercury-levels-commercial-fish-and-shellfish-1990-2012 As someone who loves sushi, tuna, and eats 2+ cans of sardines a day I'm worried about under-estimating mercury intake based on decade old measurements. Is that a reasonable worry?

Answer

Damn that’s a lot of sardines.

Fish mercury content is based on their position in the food chain.

Sardines eat plankton, which means toxins (the non-buzzword kind) aren’t high in them.

Predatory fish tend to be very high in mercury and other things because they’re eating other fish that have mercury in them. Eventually you have a fish that has swallowed a bunch of little mercury sources and now has a high content.

Just choose what kind of fish you eat wisely.