Mass Mortality of Cherax quadricarinatus (Von Martens, 1868) reared in Sicily (Italy): Crayfish Plague Introduced in an Intensive Farming Freshwater Crayfish

An episode of mortality in farmed redclaw crayfish, Cherax quadricarinatus, reared in Sicily, is described. Histological and PCR methods were used to identify the oomycetes, Aphanomyces astaci, as the causative agent of the disease. Mortality up to 30%, and haemocytic melanising response against hyphae in affected specimens, indicates a certain resistance of C. quadricarinatus towards A. astaci. Procambarus clarkii reared in the same facility is hypothesized to be the carrier of the pathogen. Evidence of mortality in redclaw crayfish held at higher temperatures than any previously investigated episodes is discussed in this paper.