Crayfish Plague / Crawfish Plague : The Plague Fungus ( Aphanomyces Astaci )

Segment with brown (ventral) markings shows signs of 
typical infection from fungus.
Segments either side indicate healthy muscle tissue

Crayfish Plague / Crawfish Plague :  The Plague Fungus (Aphanomyces Astaci)

Aphanomyces Astaci commonly referred to as crayfish plague is an oomycete or water mould that infects only crayfish species. It is endemic of North America and is carried by North American crayfish species; signal crayfish Pacifastacus Leniusculus, Procambarus Clarkii and Orconectes Limosus. A. Astaci was introduced into Europe through imports of North American species of crayfish. Native European crayfish populations are not resistant to this oomycete. It has since devastated native crayfish stocks throughout the continent.



- Fungus attaches to the shell of the crayfish
- Fungus grows filaments that penetrate the shell into the soft tissue below
- Infected crayfish dies in 6 - 10 days

Crayfish Plague / Crawfish Plague :  The Plague Fungus ( Aphanomyces Astaci )
- Introduced to Italy via ballast water discharge from Introduced to Italy via ballast water discharge from
North American ship in 1860

- Other countries it spread to: Sweden (1907), Spain (1958), Norway (1971), United Kingdom  (1981), Turkey (1987) (1984) (1981),
- The plague has wiped out native populations of  The plague has wiped out native populations of
the noble European crayfish ( the noble European crayfish (Astacus Astacus)
almost to the point of extinction in some locations almost to the point of extinction in some locations
- The signal crayfish ( The signal crayfish (Pacifastacus Leniusculus)) has  has  been introduced as a replacement  been introduced as a replacement

 Other effects as a result of the  Other effects as a result of the  introduction of non introduction of non-native crayfish: native crayfish :
- Re-introduced the fatal plague to other  introduced the fatal plague to other  crayfish populations in Europe crayfish populations in Europe
- Reduced biological diversity Reduced biological diversity
- Disrupted host environment and community Disrupted host environment and community
- Provided a now permanent source of plague  Provided a now permanent source of plague fungus
- Reduced fisheries in Europe Reduced fisheries in Europe
- Changed the diet of indigenous mammals in  Changed the diet of indigenous mammals in  Europe

Controlling ballast water discharge to reduce chance of more species  to reduce chance of more species introductions (Maritime shipping)
“the prevention, reduction  the prevention, reduction  or elimination of the  or elimination of the  transfer of harmful aquatic  transfer of harmful aquatic  organisms and pathogens  organisms and pathogens  through the control and  through the control and  'management of ships'  ballast water and  ballast water and  sediments, consistent with  sediments, consistent with  international law international law”
(International Maritime Organization)