Science Serving Maryland's Coasts
Robert Mason, Ph.D.
Chesapeake Biological Laboratory
Analysis of Size-Specific Total Mercury Concentrations in Predatory Fish of Maryland Reservoirs
The bioaccumulation of Hg, as methylmercury (MMHg), can reach toxic levels in top predatory fish that can be unsafe for human consumption. Over 40 states have fishing advisories due to the health risks associated with Hg. This research was completed to determine the HgT concentration in top predatory fish of MD reservoirs and investigate the relationships between Hg concentration and size. Large mouth bass and black crappie and/or bluegill species of fish were collected at five different reservoirs, and were analyzed for HgT. Large mouth bass was the only species that showed increased HgT concentrations with size class. Weight proved to be a better predictor of HgT concentrations, as four out of the five reservoirs showed a significant correlation between HgT and weight in large mouth bass. Only one reservoir was significantly different in terms of the amount of HgT in large mouth bass. In this study, we found that there were several large mouth bass from MD reservoirs that exceeded the common Hg advisory level (0.5 mg Hg/ kg fish tissue) and a few that approached the FDA action level (1.0 mg Hg/kg fish).
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