Affected children show lowered intelligence, impaired hearing and poor coordination. Their verbal and motor skills may be delayed. Mercury in their diets can cause early death, weight loss, and problems with their ability to reproduce. Unfortunately, wildlife cannot read fish advisories or change their eating habits in order to avoid mercury contamination. Once in a lake or river, mercury is converted to methylmercury by bacteria and other processes.
Fish absorb methylmercury from their food and from water as it passes over their gills.
Mercury is tightly bound to proteins in all fish tissue, including muscle. There is no method of cooking or cleaning fish that will reduce the amount of mercury in a meal. Methylmercury in the water and sediment is taken up by tiny animals and plants known as plankton. Minnows and juvenile fish eat large quantities of plankton over time. Large predatory fish consume many smaller fish, accumulating methylmercury in their tissues.