Why do fish contain mercury?
Fish absorb methylmercury: Methylmercury in fish mainly comes from mercury in ocean sediment that is transformed into methylmercury by microorganisms. This organic form of mercury is absorbed by the tissues of fish through their gills as they swim and through their digestive tracts as they feed. Some fish contain more mercury than others: Mercury levels differ from one species of fish to the next. This is due to factors such as type of fish, size, location, habitat, diet and age. Fish that are predatory (eat other fish) are large and at the top of the food chain, and so tend to contain more mercury. Fish that contain higher levels of mercury include: Shark Ray Swordfish Barramundi Gemfish Orange roughy Ling Southern bluefin tuna. Fish with lower mercury levels: Examples of fish that contain lower levels of mercury include: Shellfish including prawns, lobsters and oysters Salmon Canned tuna.
