Note technique la situation des écrevisses en france résultats des enquêtes nationales réalisées entre 1977 et 2006 par le conseil supérieur de la pêche

Abstract

Since the end of the XIXth century, the distribution of crayfish in France has gone through deep changes, and the introduction of allochtonous crayfish, essentially from the North American continent, has forever changed the French and European crayfish landscape. The four surveys organised in France by the Conseil supérieur de la pêche since 1977 allow following the evolution of the different species of crayfish present on the national territory, showing each time the large expansion of the exotic species and the recess of the native species. The 2006 survey shows the same tendency and the situation of our three native species must now be considered as alarming. Two of these species, Austropotamobius torrentium and Astacus astacus, are close to extinction, and the third one, Austropotamobius pallipes, can now be found on the up-most parts of the watersheds, confined in areas where the first signs of climatic changes can be seen, and under the pressure of the exotic species which are still making their way further up. Pacifastacus leniusculus and Procamabrus clarkii are showing the strongest geographical expansion during the 2001-2006 period. Everywhere they appear to be very strong competitors, more aggressive, resistant to pathologies, able to colonize varied environments. They are indeed colonizing new departments, new watersheds, and thus eliminating native species.