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Total and Methyl Mercury in 1994-5 Lake Michigan Lake Trout and Forage Fish
Citation:
RAYMOND, B. AND R. ROSSMANN. Total and Methyl Mercury in 1994-5 Lake Michigan Lake Trout and Forage Fish. JOURNAL OF GREAT LAKES RESEARCH. International Association for Great Lakes Research, Ann Arbor, MI, 35(3):438-446, (2009).
Impact/Purpose:
Results presented in the paper will serve as a baseline for comparison of future measurements of mercury in Lake Michigan fish.
Description:
Total and methyl mercury were analyzed in Lake Michigan fish collected in 1994 and 1995 as part of the Lake Michigan Mass Balance project (LMMB). One predator fish species and five forage fish species were analyzed to determine the bioaccumulative nature of mercury. These data in conjunction with another study on the mercury effects on the lower food chain of Lake Michigan, gave a complete description of how mercury concentrates to levels of concern for human consumption. The 1994-95 lake trout data were compared to the US EPA consumption thresholds for MeHg. Based on a person weighing 70kg and a fillet serving portion of 227g, none of the lake trout sampled in the study were below the unrestricted consumption threshold. Only 50% of the lake trout analyzed had MeHg concentrations below the two meals per month threshold. The concentrations determined in the 1994-5 Lake Michigan fish were significantly less than historic fish mercury concentrations in Lake Michigan, as well as, Lake Ontario. Based on this comparison, mercury levels in Lake Michigan fish have decreased. The decrease seems to have coincided with the mercury abatement policies implemented in the 1970s, namely the Clean Water Act of 1972 (CWA) and the 1978 Great Lakes Water Quality Agreement (GLWQA). The temporal mercury concentration trend in fish significantly correlated with the mercury flux to Lake Michigan sediments. Results presented in the paper will serve as a baseline for comparison of future measurements of mercury in Lake Michigan fish.
