Twenty-seven years of observations revealed changes in seabird abundance associated with changes in oceanographic conditions and ocean productivity. The regime shift of 1976, El Niño of 1983–1984, and the prolonged decline in productivity of the 1990s were followed by great declines in several historically common species, particularly those foraging offshore: the Sooty Shearwater, a non-breeding visitor from the southern hemisphere, and three alcids breeding regionally—the Common Murre, Cassin's Auklet, and Tufted Puffin. Species that increased included two offshore foragers associated with fishing vessels (Black-footed Albatross and Northern Fulmar), one inshore-foraging species that nests in southern California and Mexico (Brown Pelican), and an apparently adaptable alcid (Rhinoceros Auklet) that forages inshore and has increased all along the west coast of North America. The decrease of eight offshore species and two abundant, widespread species coinciding with an increase in three fishing-vessel associates and two nearshore foragers imply a decline in oceanic productivity.