Estuaries around the world are in a state of decline following decades or more of overfishing, pollution, and climate change. Oysters (Ostreidae), ecosystem engineers in many estuaries, influence water quality, construct habitat, and provide food for humans and wildlife. In North America's Chesapeake Bay, once-thriving eastern oyster (Crassostrea virginica) populations have declined dramatically, making their restoration and conservation extremely challenging. Here we present data on oyster size and human harvest from Chesapeake Bay archaeological sites spanning ∼3,500 y of Native American, colonial, and historical occupation. We compare oysters from archaeological sites with Pleistocene oyster reefs that existed before human harvest, modern oyster reefs, and other records of human oyster harvest from around the world. Native American fisheries were focused on nearshore oysters and were likely harvested at a rate that was sustainable over centuries to millennia, despite changing Holocene climatic conditions and sea-level rise. These data document resilience in oyster populations under long-term Native American harvest, sea-level rise, and climate change; provide context for managing modern oyster fisheries in the Chesapeake Bay and elsewhere around the world; and demonstrate an interdisciplinary approach that can be applied broadly to other fisheries.historical baseline | archaeological shellfish | fossil shellfish | marine fisheries | environmental management

Sea-level rise during the late Pleistocene and early Holocene inundated nearshore areas in many parts of the world, producing drastic changes in local ecosystems and obscuring significant portions of the archeological record. Although global forces are at play, the effects of sea-level rise are highly localized due to variability in glacial isostatic adjustment (GIA) effects. Interpretations of coastal paleoecology and archeology require reliable estimates of ancient shorelines that account for GIA effects. Here we build on previous models for California's Northern Channel Islands, producing more accurate late Pleistocene and Holocene paleogeographic reconstructions adjusted for regional GIA variability. This region has contributed significantly to our understanding of early New World coastal foragers. Sea level that was about 80-85 m lower than present at the time of the first known human occupation brought about a landscape and ecology substantially different than today. During the late Pleistocene, large tracts of coastal lowlands were exposed, while a colder, wetter climate and fluctuating marine conditions interacted with rapidly evolving littoral environments. At the close of the Pleistocene and start of the Holocene, people in coastal California faced shrinking land, intertidal, and subtidal zones, with important implications for resource availability and distribution.

Twenty-first-century global warming poses a significant threat to the cultural heritage of coastal regions, but the effects of sea-level rise and changing weather patterns will not be evenly distributed. In addition, continued urban, agricultural, and industrial development concentrated in coastal areas contributes to the destruction of cultural resources. Mitigation of these threats requires rapid action on the part of archaeologists and public land managers. This study presents a method for quickly evaluating relative resource vulnerability at national, regional, and local scales, using data that is available for all United States coastlines, as well as many other coastlines around the world. Three regional case studies-the mountainous coast of California's Santa Barbara Channel, the wetlands and sandy shores of Texas, and the protected estuarine shores of Virginia's Chesapeake Bay-are compared to shoreline vulnerability for the United States as a whole. In each of these regions, sites have already been submerged under rising tides, lost to storm erosion, or destroyed by human activities. Variability in coastal geomorphology, rates of relative sea-level rise, and the structure of prehistoric settlement and subsistence systems, however, produce different patterns of vulnerability.