Mercury levels in freshwater fish of the state of South Carolina

Samples of fish from freshwater sources of rivers, lakes and ponds all over the state of South Carolina were collected during the Summer of 1974 and 1975. The fish collected were Bass, Bluegill, Redbreast, Catfish, Shad, Carp, Crappie, Mudfish and Pike. Samples were analyzed using the flameless atomic absorption procedure outlined by Hatch and Ott, and Uthe et al as modified for use with Perkin-Elmer, Coleman MAS-50 mercury analyzer. Triplicate samples of fish tissue were analyzed by wet digestion method. The mean mercury levels in ppb were determined for baseline mercury levels. A significant finding of this report is that those species for which fish of widely differing weights were analyzed, larger fish had higher mercury levels. Mercury levels exceeding the U.S. Food and Drug Administration guideline of 500 ppb for fish tissues have been found in the Mudfish from Edisto River and Pike fish from Lake Murray. Higher levels of mercury occurred in the highly vascularized blood tissues of liver and kidney than in muscle. Carnivorous and bottom-feeding fishes are the most reliable indicators of mercury pollution.