Fish Consumption Health Advisories

Methylmercury is an organic form of mercury that can accumulate in fish to levels that may be toxic to humans who eat them regularly over a prolonged period of time.  The species of fish most susceptible to this accumulation of methylmercury are those that feed primarily on other fish such as largemouth bass.  This is a problem in many areas of Florida and in many other areas throughout the United States and the world.

The level of mercury in an individual fish depends upon its age and diet.  Older, larger fish usually contain more mercury than younger, smaller fish from the same water.  The amount of mercury in a fishes diet depends upon what it eats and the water it lives in.  Most of the mercury to which fish are exposed is deposited from the atmosphere by air currents and rain.  Municipal incinerators, medical waste incinerators, the combustion of fossil fuels, mining and smelting are the principal sources of atmospheric mercury.  These sources may be nearby or on the other side of the earth.  Efforts are under way to control Florida sources.  Whether mercury from the atmosphere will be incorporated into the diet of the fish you catch depends mainly upon water quality. DEP is working to understand the environmental factors that determine fish mercury levels and how those levels can be reduced.

Mercury is a naturally occurring element for which human beings are believed to have some tolerance. Tolerances are established by the Department of Health.  Fish that have more than 1.5 parts per million in the edible flesh are considered unsafe for any consumption.  Those containing less than 0.5 parts per million are considered safe for unlimited consumption.  Consumption should be limited for fish with concentrations from 0.5 to 1.5 parts per million of mercury in edible flesh.  Women of childbearing age and children should limit consumption of these fish to a single serving per month.  Other adults should limit consumption of these fish to a single serving per week.  These values are based on a body weight of 156 lbs and an 8 ounce (half-pound) serving of fish.  If you weigh less, it would be safer to consume less.  A conservative approach for eating largemouth bass from untested waters would be to follow the advice given for limited consumption – one serving per month for women of childbearing age and children and one serving per week for other adults.

This site lists those waters where fish likely to be consumed by humans have been tested.  It shows which waters tested safe for any amount of consumption, which are safe for limited consumption and which are unsafe for any consumption.  This site also gives a map showing those waters for which fish consumption advisories are in effect.  The complete texts of Department of Health advisories are also given.

For other information about fish consumption health advisories you may wish to refer to the Florida Fish and Wildlife Commission, which deals with this subject.