Fifty years of research to counter the decline of the European flat oyster (Ostrea edulis): a review of French achievements and prospects for the restoration of remaining beds and revival of aquaculture production

In the fifty years since the introduction of the Pacific oyster Crassostrea gigas and the first reports of the parasites Marteilia refringens and Bonamia ostreae in European waters, numerous research projects dedicated to the native European flat oyster Ostrea edulis have been conducted, notably in France. Most of these projects have been dedicated to developing controlled reproduction and hatchery technology for seed production, examining pathological aspects to understand and control diseases, and using genetics to develop resistant lines. While the long-term objective of most studies has been to revive the aquaculture production of O. edulis, a smaller number have addressed the ecology of local remnant beds and reefs in France. This article provides an overview of the major outcomes of all these projects, focusing on results obtained in France and prospects for future work there, taking into account the rising interest in increasing aquaculture production and ecological motivation to restore declining populations as part of the framework of the Native Oyster Restoration Alliance (NORA) and in line with UN Decade for Ecosystem Restoration.