Restaurer les fonctionnalités des écosystèmes : Proposition pour la réintroduction de l’esturgeon de l’Atlantique Acipenser oxyrinchus Mitchill, 1815 (Pisces, Acipenseridae) pour sauver la grande mulette Margaritifera auricularia (Spengler, 1793) (Mollusca, Bivalvia, Margaritiferidae) de l’extinction

The giant pearl mussel Margaritifera auricularia, previously widespread in Western Europe, still survives in a few aging core populations, which have not been recruiting for several decades. The extirpation of its main host-fish, the European Sturgeon Acipenser sturio, is believed to be the main cause of its rarefaction. A few decades seem to be left to save the giant pearl mussel from extinction. A European Sturgeon restoration plan is ongoing, but given the late sexual maturity of this species, we cannot expect a return of sexually mature individuals in rivers in France before ca. 15 years. In order to restore ecosystems’ functionality and save the Giant Pearl Mussel from extinction, we suggest the reintroduction of a similar species: the Atlantic Sturgeon A. oxyrinchus. This species is the least threatened of the Acipenseridae and was present in France at least between 3 000 BC and 200 AD. The interspecific competition risk with the European Sturgeon, as well as the introgression risk, can be eliminated as both species have coexisted in the past. The possibility of reintroducing the Atlantic Sturgeon gives new insights for the recovery of Giant Pearl Mussel populations.