In large enough doses, mercury is toxic to mammals, birds, and fish. Mercury can cause severe nerve and brain damage, sight and hearing loss, and birth defects. Levels that cause serious illness have only occurred in rare situations of gross pollution or accidental poisonings.

Since 1995, the FDA has recommended that pregnant women or women who may become pregnant limit their intake of shark or swordfish to one meal per month. The FDA also found that consumption advisories are unnecessary for, at least, the top ten seafood-marketed species: canned tuna, shrimp, pollock, salmon, cod, catfish, clams, flatfish, crabs, and scallops.

The State of Florida has assumed the role of advising residents of potential health risks from eating non-commercially caught fish. Florida follows federal Environmental Protection Agency recommendations to test for total mercury and uses the conservative assumption that all mercury in fish flesh is toxic. The state uses a tiered health advisory format in an effort to further limit potential exposure risks. Following these guidelines, the state has issued over ninety advisories for streams, lakes, and marine waters since 1989.

Marine fish advisories are complex to develop. Marine fish are not confined and can range from one area to the next. These areas can extend to include the entire state and throughout the Gulf of Mexico, Caribbean Sea, and South Atlantic. Mercury accumulation rates are primarily based on diet, age, and growth rate of the fish. The final factors affecting our ability to monitor mercury levels in marine fish is Florida’s vast area and limited sampling opportunities.

Since 1989 the state has collected data on mercury levels in several species of marine fish from around Florida. Accurate species identification and location information is critical. The majority of collections have been made by the Florida Marine Research Institute during regular surveys and fishing tournaments.