Marine foundation species (e.g. mangroves, kelp, corals, oysters) are critical to the structure and resilience of coastal ecosystems and provide key ecosystem services. Like many other foundation species, Olympia oysters ( Ostrea lurida) have suffered severe population declines, to the point of local extinction in some estuaries. The restoration of these populations is a priority for maintaining ecosystem function of estuaries along the west coast of North America. In the first synthesis of all native oyster restoration projects conducted from California, USA, to British Columbia, Canada, we analyzed project motivations, goals, methods, and outcomes to provide a picture of the status of restoration for this species.
We found that restoration projects are currently spread unevenly across the species’ range, driven by local goals and implemented with differing, sometimes contrasting approaches. We highlight the value of regional strategic planning and decision support tools to evaluate project design and methods for restoration, including the selection of substrates and the targeted use of aquaculture. We recommend future investment in larger projects, which our analysis found were more cost-effective, but which have been relatively rare for this species. We also recommend that funders support monitoring over broader temporal and spatial scales than in the past to better characterize long-term effects of restoration on oyster populations and the services they provide beyond the project footprint. We found that most projects successfully supported native oysters and engaged local communities, and recommended similar efforts to continue to enhance understanding of Olympia oysters, which remain unfamiliar to many coastal residents. We believe that the results of this synthesis are broadly applicable to marine foundation species generally, and can inform restoration and conservation efforts worldwide.