| Summary: | On the basis of a literature review and new studies in Brandenburg, northeast
Germany, the status and the genetic structure of the noble crayfish Astacus astacus (L.)
in Germany are described. The present situation is characterized by a patchy distribution
comprising at least 719 stocks, documented after 1990. Stocks are rnainly confined to the
uppermost stretches of small streams or to small lakes without connection to other surface
waters. As is typical of Europe, geographical isolation, inbreeding and genetic drift may
play an important role in the population structure of the noble crayfish in Germany.
By means of RAPD-PCR, stocks in Brandenburg (Br1, Br2 and Br3),
Schleswig-Holstein (SH) and Bavaria (B1 and B2) were analysed for their genetic
structure. RAPD markers show high ability to separate significantly all investigated stocks
as single populations. Mean non-dimensional distances were 5.8, 5.6 and 4.2 for SH-B,
SH-Br and B-Br between-region cornparisons, respectively. Values for within-region
comparisons were 3.1 and 1.3 for B-B and Br-Br, respectively. However, even the three
different lakes located in Brandenburg, which are only about 20 km apart from each other,
contained significantly distinguishable populations.
So far it is not possible to judge whether the distinct populations result frorn isolation
of stocks or indicate local adaptations to the specific environmental conditions. The answer
to this question is important with respect to conservational management and the design of
restocking programmes. A decision tree for the inventory and monitoring of noble crayfish
stocks is suggested, since some areas in the northeast of Germany rnay still contain rnany
unknown stocks, which are of considerable importance for conservation.
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