Crayfish plague
Encyclopedia
Crayfish plague, Aphanomyces astaci, is a water mould
that infects crayfish
, most notably the European Astacus
which dies within a few weeks of being infected. When experimentally tested, species from Australia
, New Guinea
and Japan
were also found to be susceptible to the infection.
in 1859, either with imported crayfish from North America, or in ballast water. After its original introduction in Italy in 1860, it spread quickly through Europe and was discovered in Sweden
in 1907, in Spain
in 1972, in Norway
in 1971, in Great Britain
in 1981, in Turkey
in 1984 and in Ireland
in 1987.
In 1959, to bolster dwindling stocks of native crayfish, the signal crayfish
was introduced to Sweden
. The signal crayfish was known to be resistant, and it was not recognised at that time that it was a carrier of the disease. After 150 years of contact, no resistance has been discovered in native European crayfish.
Implantations of the signal crayfish was the reason for the spread of the disease to United Kingdom and Ireland. Transport of signal crayfish, red swamp crayfish
and infected native European freshwater crayfish between waters is the main cause for contamination. Transmission of the disease through items that has been in contact with contaminated water, for example a fishing tool
or footwear is also possible. The spores are also sensitive to high or low temperatures. Most authorities have local rules and regulations that the amount of water moved between different waters (in for example a boat) is minimised. It is usually also recommended to only use fishing bait
from the same lake when fishing, alternatively freeze
it to at least -10 C for one day before use, if risk for contamination exists. The fungal spores of crayfish plague disappear from an infected water system (connected lakes and rivers) in a few weeks after the last infected crayfish is gone. Reintroduction is then possible, as long as no infected waters are in contact with the lake.
s in the oömycete can include appearing in daytime (crayfish are typically nocturnal) and a lack of co-ordination.
Water mould
Oömycota or oömycetes form a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms . They are filamentous, microscopic, absorptive organisms that reproduce both sexually and asexually...
that infects crayfish
Crayfish
Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...
, most notably the European Astacus
Astacus
Astacus is a genus of crayfish found in Europe and western Asia, comprising three extant and four extinct species....
which dies within a few weeks of being infected. When experimentally tested, species from Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
and Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
were also found to be susceptible to the infection.
History
Crayfish plague first arrived in Europe in ItalyItaly
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
in 1859, either with imported crayfish from North America, or in ballast water. After its original introduction in Italy in 1860, it spread quickly through Europe and was discovered in Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
in 1907, in Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
in 1972, in Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
in 1971, in Great Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...
in 1981, in Turkey
Turkey
Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...
in 1984 and in Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...
in 1987.
In 1959, to bolster dwindling stocks of native crayfish, the signal crayfish
Signal crayfish
The signal crayfish, Pacifastacus leniusculus, is a North American species of crayfish. It was introduced to Europe in the 1960s to supplement the Scandinavian Astacus astacus fisheries, which were being damaged by crayfish plague, but the imports turned out to be a carrier of that disease...
was introduced to Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
. The signal crayfish was known to be resistant, and it was not recognised at that time that it was a carrier of the disease. After 150 years of contact, no resistance has been discovered in native European crayfish.
Transmission
Procambarus clarkii
Procambarus clarkii is a freshwater crayfish species, native to the Southeastern United States, but found also on other continents, where it is often an invasive pest. It is known variously as the red swamp crawfish, red swamp crayfish, Louisiana crawfish, Louisiana crayfish or mudbug.-Range and...
and infected native European freshwater crayfish between waters is the main cause for contamination. Transmission of the disease through items that has been in contact with contaminated water, for example a fishing tool
Fishing
Fishing is the activity of trying to catch wild fish. Fish are normally caught in the wild. Techniques for catching fish include hand gathering, spearing, netting, angling and trapping....
or footwear is also possible. The spores are also sensitive to high or low temperatures. Most authorities have local rules and regulations that the amount of water moved between different waters (in for example a boat) is minimised. It is usually also recommended to only use fishing bait
Fishing bait
Fishing bait is any substance used to attract and catch fish, e.g. on the end of a fishing hook, or inside a fish trap. Traditionally, nightcrawlers, insects, and smaller bait fish have been used for this purpose...
from the same lake when fishing, alternatively freeze
Freezing
Freezing or solidification is a phase change in which a liquid turns into a solid when its temperature is lowered below its freezing point. The reverse process is melting....
it to at least -10 C for one day before use, if risk for contamination exists. The fungal spores of crayfish plague disappear from an infected water system (connected lakes and rivers) in a few weeks after the last infected crayfish is gone. Reintroduction is then possible, as long as no infected waters are in contact with the lake.
Signs
Infection with Aphanomyces astaci is accompanied by few signs in its early stages, and the first indication of infection may be mortality. In the later stages, the muscles of the tail may appear whitened, or brownish-red where blood cells have encapsulated the hyphae. The effects of the neurotoxinNeurotoxin
A neurotoxin is a toxin that acts specifically on nerve cells , usually by interacting with membrane proteins such as ion channels. Some sources are more general, and define the effect of neurotoxins as occurring at nerve tissue...
s in the oömycete can include appearing in daytime (crayfish are typically nocturnal) and a lack of co-ordination.