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Mercury in Fish

Why should I eat fish?

Fish, in general, are: 

  • An important part of a healthy, well-balanced diet. The American Heart Association recommends eating at least two servings of fish each week.
  • A good source of protein, vitamins, and heart healthy omega-3 fatty acids. It is important for pregnant women to eat fish because omega-3 fatty acids help the baby's brain develop. 

How does mercury get into fish and shellfish?

Mercury is a metal that comes from natural sources, mining, and air fallout from burning coal and other fuels. 

  • The Northern California Coast Range, where Clear Lake is located, is naturally rich in mercury and other ores.
  • The Sulpher Bank Mercury Mine, located on the shore of Clear Lake, has caused mercury contamination of the lake sediments

Once mercury gets into the water, it settles to the bottom where bacteria in the mud or sand change it to the organic form methylmercury. Methylmercury, a more toxic form of mercury, gets into fish and shellfish through the food they eat. It is passed up the food chain from small plants and animals to larger, older fish, where it builds up.

For more information visit the Environmental Health page.