Great Lakes Herring Gull Egg PCB Concentrations Indicate Approximate Steady-State Conditions

Abstract

PCB concentrations in Great Lakes herring gull eggs exhibited decreases following the imposition of regulations banning PCB manufacture. However, gull egg concentrations in Lakes Superior, Michigan, Huron, and Ontario now appear to have stabilized or slightly increased. Concentrations in Lake Erie gull eggs still appearto be decreasing, though the variability in these data may limit the ability to differentiate trend changes until more data are available. This pattern is consistent with previously reported findings of stabilizing PCB concentrations in Great Lakes fishes and suggests that future improvements will be slow and difficult to discern.