Human impacts on nearshore shellfish taxa: A 7,000 year record from Santa Rosa Island, California

Within the broad framework of historical and behavioral ecology, we analyzed faunal remains from a large habitation site (CA-SRI-147) on Santa Rosa Island to explore a 7,000 year record of coastal subsistence, nearshore ecological dynamics, and human impacts on shellfish populations. This long, stratified sequence provides a rare opportunity to study the effects of prolonged human predation on local intertidal and nearshore habitats. During the past 7,000 years, the Island Chumash and their predecessors had significant impacts on nearshore ecosystems, caused by growing human populations and depletion of marine and terrestrial ecosystems. At CA-SRI-147, local depletion of higher ranked shellfish species stimulated dietary expansion and a heavier reliance on lower-ranked shellfish taxa and more intensive exploitation of nearshore and pelagic fishes. In the Late Holocene, as local ecosystems were increasingly depleted, the Island Chumash relied increasingly on craft specialization and trade to meet their subsistence needs. Native peoples clearly impacted Channel Island ecosystems, but data from CA-SRI-147 suggest that they adjusted their subsistence strategies toward productive fisheries that sustained the high population densities and sociopolitical complexity recorded by early Spanish chroniclers at European contact.