DISTRIBUTION, POPULATION-STRUCTURE AND CONSERVATION OF AUSTROPOTAMOBIUS-PALLIPES IN PORTUGAL

Austropotamobius pallipes has suffered a considerable reduction in ran ge and abundance over the last two decades. The main hypotheses to exp lain this situation are :environmental degradation, critical climatic conditions, and the crayfish plague, though the presence of Aphanomyce s astaci as the aetiological agent is to be confirmed. White-clawed cr ayfish populations are now confined to a few small areas in the north- eastern part of the country and risk total extinction. Population char acteristics are presented. Sex ratio is balanced and maximum size is s mall, very few individuals being larger than 75 mm. Four age-classes w ere identified through modal analysis. Females become sexually mature during the second year. Several conservation actions are proposed.