Many people fish for the enjoyment of it, releasing their catch right after they land it. Some eat their catch occasionally. But some people fish daily or weekly for food. They may not know that some of their catch may be contaminated with mercury.
Several government agencies, notably the Environmental Protection Agency and the Food and Drug Administration, post warnings about how people, especially pregnant women and young children, should limit how much fish they eat and should avoid some types of fish.
Mercury, a toxic metal that is especially harmful to pregnant women and children, collects in varying levels in most fish. Mercury occurs naturally in fish, but it also seeps into rivers and lakes near coal-burning power plants, old mines, or industrial sites.
Many low-income families and immigrants who fish daily or weekly to put food on their table do not read the government websites that carry these warnings.
Mercury can seriously damage the development of nerves and the brain in fetuses and children. In adults, too much mercury for too long a time can cause vision loss and difficulty walking.
The EPA says adults can eat as much as they want of some fish, but there are stricter limits for fish that eat other fish-predator fish. Freshwater predator fish include white bass, largemouth spotted bass, and catfish. Bigger, older specimens of these fish are likely to carry even more mercury than small ones.
Although health experts warn about eating too much fish, they do not want people to give up fish entirely. Fish is rich in protein and in omega-3 fatty acids that are beneficial for the heart. Still, they believe the government should do more to inform anglers about simple ways to lessen the danger, such as eating more of safer species like sunfish, crappie, and perch.
The EPA's advice on consumption of fish is at http://www.epa.gov/mercury/advisories.htm.