Why is there mercury in tuna?

Nearby anthropogenic sources, such as coal burning and mining of iron, can contaminate water sources with methylmercury, which is efficiently absorbed in the bodies of fish. ... Fish and shellfish concentrate mercury in their bodies, often in the form of methylmercury, a highly toxic organic compound of mercury. read more

Mercury in the fish we like to eat is a big problem in the United States and increasingly around the world. Mercury itself is a naturally occurring element that is present throughout the environment and in plants and animals. read more

The FDA characterizes shrimp, catfish, pollock, salmon, sardines, and canned light tuna as low-mercury seafood, although recent tests have indicated that up to 6 percent of canned light tuna may contain high levels. read more

There are two main kinds of canned tuna: chunk light and solid or chunk white (albacore). All canned white tuna is albacore. Its mercury levels are almost three times higher than the smaller skipjack tuna, used in most canned light tuna products. read more