Surf scoters (Melanitta perspicillata) were collected from 6 locations in San Francisco Bay during January and March 1985. Overall, mean concentrations of cadmium and zinc were higher in livers of scoters from the southern region of the Bay, whereas mean iron and lead were higher in those from the northern Bay region. Mean concentrations of arsenic, copper, lead, zinc, aluminum (January only) and iron (January) also differed among individual locations. Mean concentrations of copper and zinc increased, arsenic decreased, and cadmium remained the same between January and March. Selenium and mercury concentrations in scoter livers were not significantly correlated (P>0.05), but cadmium concentrations in livers and kidneys were positively correlated (P<0.0001), and body weight was negatively related to mercury concentration in the liver (P<0.05). Body weight differed among locations but not between January and March. Body weight was correlated with lipid content (P<0.0001). DDE and PCBs were each detected in 34 of 36 scoter carcasses. DDE increased significantly between January and March at Richmond Harbor, but PCBs did not differ between January and March at the 3 locations that could be tested.