Geographic Distribution and Intertidal Population Status for the Olympia Oyster, Ostrea lurida Carpenter 1864, from Alaska to Baja

ABSTRACT Despite the recently renewed interest by ecologists and government agencies to reestablish historical populations of the Olympia oyster, focus has been limited to projects located at the north of this species' range, with little or no attention to southern California and Baja populations. In addition, historical information on the status of natural populations across the range has been mainly qualitative in nature, with no comprehensive information on the current status of natural populations. The focus of this study was to conduct the first large-scale quantitative biogeographic survey of remnant populations of the Olympia oyster and to identify suitable sites in southern California for future restoration projects. We surveyed intertidal populations at 24 historical sites during spring and summer 2005 and summer 2006, established presence/absence and collected data on densities and percent cover. Average maximum densities ranged from 0.0–36.7 ± 12.1 oysters per 0.25 m2. In southern California, i...