Crayfish plague is a fungal disease that has the potential to cause large-scale mortality of freshwater crayfish in Australia. At present, the disease does not occur in Australia. However, it is important that state and territory governments and the red-claw, yabby and marron aquaculture industries are adequately prepared to manage a disease outbreak, because an incursion of the disease could devastate the freshwater crayfish aquaculture industry as well as wild populations of crayfish. The aetiological agent of crayfish plague is the oomycete, Aphanomyces astaci Schikora. Oomycetes (commonly called water moulds) are not considered to be ‘true fungi’ taxonomically, but have been placed in the phylum Oomycota. Within this phylum is the family Saprolegniaceae, which consists of the Achlya, Aphanomyces and Saprolegnia genera, with some species being pathogens of crustaceans, fish and plants.
|Giant Freshwater Crayfish|
Of the commercial crayfish species in Australia, the Red Claw Crayfish (Cherax quadricarinatus) and the yabby (Cherax destructor) have been tested and are susceptible to the disease, but there are no published reports of the susceptibility of marron (Cherax tenuimanus). Only a few Australian species of crayfish have been experimentally challenged with crayfish plague, but it is safe to assume that all Australian freshwater crayfish may be highly susceptible to infection. The susceptibility of many freshwater decapods to infection with A. astaci is unknown. Consequently, the likelihood of animals such as freshwater crabs and shrimp in Australia becoming carriers or developing clinical disease following infection with A. astaci in the wild is also unknown.