ABSTRACT
The native, European, crayfish fauna belong to a single family, Astacidae, with two genera and five recognized species: Astacus astacus, Astacus leptodactylus, Astacus pachypus, Austropotamobius pallipes, and Austropotamobius torrentium. Habitat degradation and loss, overfishing and the crayfish plague fungus, Aphanomyces astaci Schikora, dramatically reduced and/or eliminated many populations of these crayfish. Several North American crayfish species were intentionally introduced into Europe: Two cambarids, Orconectes limosus was introduced in 1890s, and Procambarus clarkii in the 1970s, and one astacid, Pacifastacus leniusculus, in 1960s. Several Australian parastacid species, genus Cherax, have been or are being cultivated on a minor scale in Europe. Orconectes limosus stock in Europe was established by a successful stocking of 100 specimens from the Delaware River, Pennsylvania, USA, in a fish pond in Barnowko village, Germany. The first 60 P. leniusculus originated from California and were stocked in Sweden, initially for ecological studies of the species. In 1967–1969, great numbers of P. leniusculus were stocked in natural waterbodies in Finland and Sweden. Secondary introductions were later made with the Swedish signal crayfish to many countries in central Europe. P. clarkii was first introduced in 1973 from Louisiana to Spain with fewer that 40,000 individuals but has then spread through secondary introductions to many other south and central European countries. These introductions were often the result of modest numbers of crayfish imported live for food sales or pets. Successful stockings with alien crayfish have led to the situation that crayfish capable of resisting and carrying fungus plague are now permanently found in many of the waters that previously were inhabited by native crayfish. Alien crayfish, however, serve as food for many other animals and are of commercial value for man.
