A survey of size-specific mercury concentrations in game fish from Maryland fresh and estuarine waters

A survey of size-specific mercury (Hg) concentrations in game fish from a s ubset of Maryland fresh and estuarine waters was conducted, in which Hg con centrations in 112 fish from seven freshwater impoundments and three tidal and four estuarine locations in Chesapeake Bay and its tributaries were mea sured. Striped bass (Morone saxatilis) was the most intensively examined sp ecies. Of the fish examined, the largest freshwater sportfish contained the highest Hg concentrations. Striped bass and largemouth bass (Micropterus s almoides) from Chesapeake Bay and its tributaries contained less Hg at the same size than the same species in fresh waters. Large striped bass, chain pickerel (Esox niger), and walleye (Stizostedion vitreum) from Deep Creek L ake and Liberty Reservoir exceeded the FDA action level of 1 mg Hg/kg. Stri ped bass, largemouth bass, and white crappie (Pomoxis annularis) in other i mpoundments equaled or exceeded a common advisory level of 0.5 mg Hg/kg. La rge differences in size-normalized Hg concentrations among lakes and partic ularly between fresh and salt waters highlight the large differences in MeH g production and bioaccumulation among ecosystems. This work indicates that a more comprehensive study of Hg in Maryland fish is warranted to protect human and wildlife health.