This white paper provides back ground and rationale for the priorities laid out in the Action Plan and summarizes our current understanding of mercury in the Gulf of Mexico ecosystem. In addition, the Action Plan emphasizes the identification of special at-risk consumers who ingest larger than average amounts of Gulf of Mexico fish, especially fish with higher than average mercury concentrations . For this reason, we have structured this white paper starting with mercury exposure to humans and proceeding along the mercury flow path backwards toward mercury sources and emissions to the environment. By so doing, the major GOMA goal of mitigating the risks of mercury exposure is emphasized. This flow path approach also helps to clarify where the flow of mercury might be disrupted to reduce the risk to consumers. We need to identify the fisheries where mercury poses the greatest risk to humans (and wildlife), determine the sources of the mercury, and understand where it is being methylated.