The management of invasive crayfish in the Vosges department

Abstract

Since the end of the XIXth century, the distribution of crayfish in France has gone through profound upheavals, and the introduction of allochtonous crayfish, essentially from the North American continent, has forever changed the French and European crayfish landscape. The four national surveys on the distribution of crayfish in France carried out by the National Office for Water and Aquatic Enbiornment (ONEMA) since 1977 allow following the evolution of the different species of crayfish present on the national territory, showing each time the considerable expansion of the introduced species and the decline of the native species. The situation of the three native crayfish species must now be considered alarming. The situation of the three native crayfish species must now be considered alarming. Two of these species, Austropotamobius torrentium and Astacus astacus, are close to extinction while the third one, Austropotamobius pallipes, is "taking refuge" in the upmost parts of the watersheds. Pacifastacus leniusculus (signal crayfish) and Procamabrus clarkii (Louisana crawfish) are showing the strongest geographical expansion. Everywhere they appear to be very strong competitors, more aggressive, resistant to pathologies, able to colonize varied environments. Thereby eliminating native species. The pace of the illegal introductions seems to accelerate because new species, native of the American continent, have recently been discovered: Orconectes juvenilis in the department of the Doubs and Orconectes immunis in the departement of the Bas-Rhin. In terms of management of these species, the actions are rather rare at the national level. However, in the Vosges department, specific actions are being experimented, in particular with the owners of ponds to try to fight against the expansion of introduced crawfish and thus to protect the last populations of native crawfish.