PRELIMINARY OBSERVATION OF OCCASIONAL MORTALITY IN THE POPULATION OF FRESHWATER CRAYFISH IN THE PICOS DE EUROPA (ASTURIAS, SPAIN)
Factors associated with mortality in a population of Austropotamobius italicus, formerly A. pallipes lusitanicus, were monitored during two years in the Natural Park of Picos de Europa. Dead crayfish were submitted to the laboratory for analysis. No mass mortalities occurred during these two years. The number of mortalities was not constant throughout the year, with highest levels observed in May-June and November-December. Over the rest of the year mortality remained low. A high proportion of dead crayfish displayed signs of predation, mainly observed during the months of November and December. Other causes associated with mortality were storms and the process of moulting, especially in June. The presence of Saprolegnia in females during the reproduction season was also observed. Symptoms of Porcelain disease, or the presence of Psorospermium, were not observed during this study.