ABSTRACT
In Germany three native and five alien crayfish occur regularly in the wild. Astacus astacus, Austropotamobius torrentium, and Austropotamobius pallipes are the native species. The stocks of A. astacus were heavily affected by the crayfish plague that spread quickly in the last century beginning in the seventies in southern Germany. Isolated populations of A. astacus can still to be found in several lakes and rivers. A. torrentium is naturally distributed in the southern part of Germany and it occurs in many small rivers and brooks. A. pallipes is only known from the south-west of Germany where a few populations exist. The most widespread alien species is Orconectes limosus, which was introduced in the last century from North America. Astacus leptodactylus has been imported since the turn of the century from countries of eastern Europe and Asia Minor for the table market. Crayfish farmers first introduced Pacifastacus leniusculus in the 1960s and a few populations occur in the wild. Procambarus clarkii can be found in a few ponds and recently a population of Orconectes immunis was found in a stream. The aquarium trade probably imported both species.
