Crayfish disease diagnostics

Towards a Nordic standard

image of Crayfish disease diagnostics

Crayfish utilization is a long-standing Scandinavian tradition, which unfortunately has suffered a major drawback with the introduction of crayfish plague disease about a hundred years ago. In spite of intensive research many problems in management and diagnosis of this disease are not yet solved. To evaluate ongoing research and diagnostic methodology in different countries, representatives of diagnostic laboratories involved in crayfish disease diagnostics were invited to a workshop in Kuopio to discuss the problems with crayfish diseases. The workshop was held at the Kuopio unit of the Finnish Food Safety Authority Evira. Participants from Finland, Sweden, Norway, Estonia and Latvia were present, as well as the OIE expert from the reference laboratory for crayfish plague. In the programme of the first day the state of crayfish stocks, crayfish diseases and diagnostic methods used in each country were presented and discussed. During the second day diagnostic methods were discussed in detail, as well as research projects concerning crayfish diseases. The workshop has been made possible by way of a grant from the Nordic Council of Ministers.



A short overview about crayfish in Sweden

Crayfish and fishing of crayfish have a long tradition in Sweden. Already 1878 came the first law that restricted crayfish fishing in June-July. There was a good supply of the noble crayfish in lakes and small rivers at the end of the 19th century and crayfish was an important income for many farmers especially when the export to other countries in Europe increased. The high demand of crayfish was covered with import of living crayfish. The dumping of diseased and dead imported crayfish in the lake Mälaren just outside Stockholm 1907 resulted in the introduction of the crayfish plague in to Sweden. The infection got an epidemic spread possibly through human transmission but also through birds and other animals and 1960 was 95% of the former noble crayfish waters classified as infected with the plague. The reintroduction of the noble crayfish in plague infected waters failed and therefore started the import of the signal crayfish from United States. This introduction was successful and signal crayfish is today the major crayfish species in Swedish lakes and river systems. Today is the spread of the crayfish plague mainly due to uncontrolled release of signal crayfish. The noble crayfish is on the "red list" of species well worth to protect and signal crayfish is not allowed to be released into Swedish waters due to the risks for transmission of the crayfish plague.


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