Description: The Maryland Department of the Environment (MDE) is responsible for monitoring and evaluating contaminant levels in fish, shellfish and crabs in Maryland waters. The tissues of interest for human health include the edible portions of species (e.g., fish fillet). Such monitoring enables MDE to determine whether the specific contaminant levels in these species are within acceptable limits for human consumption. Results of such studies are used to issue consumption advisories for recreationally caught fish, shellfish, and crab species in Maryland. Additionally, since fish, shellfish, and crabs have the potential to accumulate inorganic and organic chemicals in their tissues (even when these materials are present in very low concentrations in water), monitoring of these species becomes a valuable indicator of environmental pollution in a given waterbody. Chemicals typically tested in fish tissue include those found at historically high levels in water and sediments, such as polychlorinated biphenyls (PCBs), chlorinated pesticides (e.g., DDT and decomposition compounds, dieldrin) and total and/or methyl mercury (MeHg).