GREAT-LAKES HERRING GULL EGG PCB CONCENTRATIONS INDICATE APPROXIMATE STEADY-STATE CONDITIONS

PCB concentrations in Great Lakes herring gull eggs exhibited decrease s following the imposition of regulations banning PCB manufacture. How ever, gull egg concentrations in Lakes Superior, Michigan, Huron, and Ontario now appear to have stabilized or slightly increased. Concentra tions in Lake Erie gull eggs still appear to be decreasing, though the variability in these data may limit the ability to differentiate tren d changes until more data are available. This pattern is consistent wi th previously reported findings of stabilizing PCB concentrations in G reat Lakes fishes and suggests that future improvements will be slow a nd difficult to discern.