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Gyrodactylus salaris

In 2014 the monogenean ectoparasite Gyrodactylus salaris was detected in one Norwegian salmon river, river Rana in Nordland County. No fish farms with salmon (Salmo salar) or rainbow trout (Oncorhynchus mykiss) were infected with G. salaris during 2014.

Three different G. salaris surveillance programs are conducted in 2015:

  • The surveillance and control programme for G. salaris in Atlantic salmon and rainbow trout in Norway. This program aims to detect and trace the spread of G. salaris to new river systems or fish farms (or to rivers and farms previously declared free from infection).
  • The post-treatment control programme to ascertain freedom from infection with G. salaris in Atlantic salmon. In 2015, three regions are included in this program. The main objective is to document freedom of the parasite in previously infested rivers after the implementation of eradication measures.
  • The surveillance program to document the G. salaris situation in lake Tyrifjorden. The aim is to determine whether the parasite is present in the lake or not. The program terminates in 2015.

Gyrodactylosis, caused by G. salaris, is a notifiable disease, and is listed as “Other significant disease” by the World Organisation for Animal Health - OIE. Surveillance for G. salaris has been carried out in Norwegian salmon rivers since the late 1970s.

During the period of 1975 to 2014 pathogenic strains of G. salaris have been detected on Atlantic salmon fingerlings/parr in 49 rivers, 13 hatcheries/farms with Atlantic salmon parr/smolts and 26 hatcheries/farms with rainbow trout. In addition, both pathogenic and non-pathogenic strains of G. salaris have been detected on Arctic charr (Salvelinus alpinus). As of 31th December 2014, G. salaris was present or suspected to be present in 10 Norwegian rivers, while 17 rivers are included in the The post-treatment control programme.

The Norwegian Veterinary Institute is the OIE international reference laboratory for G. salaris.



 There are a lot of other reports on Gyrodactylus salaris - all in Norwegian - available at the Norwegian page.