PARTAGER

Stage 5: Vittel > La Planche des Belles Filles

Spotlight on white-clawed crayfish

The Plateau des mille étangs’ Natura 2000 site (FR4301346), managed by the Ballons des Vosges Regional Natural Park, is known for its great biological richness and the originality of its landscapes. It forms a real mosaic in which ponds (iconic feature in the area), meadows, peat bogs, forests and 430 km of streams are tightly intertwined. It is home to fauna and flora that is rare and threatened within Europe, including the white-clawed crayfish.

Formerly prized for human consumption, the crayfish, which is easier to catch than fish, has certainly been part of prehistoric man’s food. There was also a definite economic interest in them during the Middle Ages, when night fishing using torches was regularly organised.

Today this species is rapidly declining in Europe and strictly protected in France, where its relict populations are hidden away in the headwater streams of watersheds. The Plateau des mille étangs site thus includes 46 km of protected streams, as this species is of national importance.

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Characteristics and lifestyle

The white-clawed crayfish has a brown-green back and a white belly. It is never red-orange like its invasive cousins from Louisiana or California. It is 12 cm long and weighs an average of 90 g.

This species is sedentary, but is more active during the night and hides during the day. Nowadays, it resides in streams that provide lots of shelter, which protects it from the current and predators: pebbly, gravelly bottoms or bottoms with boulders under which it hides, under banks with roots, root hairs and recesses.

State of conservation and conservation measures

The species is both demanding and very sensitive to changes in its living environment conditions. It likes streams with clear, shallow water that is of excellent quality, very well oxygenated and fresh. This makes it a species whose presence indicates a good quality of stream and water hence the importance of preserving it!

Sensitive to increasing water temperature, pollution and other species of exotic crayfish such as the American crayfish, actions financed by European programmes are carried out on the site with voluntary owners.

These actions, which combine human activities with the preservation of this species, are illustrated in particular by the development of ponds with adequate drainage systems or the installation of fences along watercourses adjacent to grazed areas.

Sources: INPN, http://pnrbv.n2000.fr, brochure “Les écrevisses indigènes et exotiques en Région wallonne” (Indigenous and exotic crayfish in the Walloon Region"), Association Theutoise pour l’Environnement). http://www.aspei.be/documentation/EcrevissesBrochure.pdf