Crayfish plague (Aphanomyces astaci)

The Norwegian Veterinary Institute (NVI) conducts crayfish plague surveillance in control areas, combat zones and risk areas.

The purpose of the program is to monitor the infection pressure and infection development in control areas and combat zones for Aphanomyces astaci, and to substantiate disease freedom and/or provide an early warning of possible infection spread in to risk areas


In 2017, no spread of A. astaci was observed in any of the monitored areas.

  • In the control zone of the Halden watercourse, A. astaci eDNA was only detected in the southern part of Lake Rødenessjøen. Here, the known presence of signal crayfish was confirmed by eDNA detection. No sign of crayfish plague was observed from the northern part of Lake Rødenessjøen (Kroksund) up to the control zone border at Fosserdam. This result was supported by positive detections of noble crayfish eDNA in all water samples from River Hølandselva and upstream. All water samples in this risk area were negative for A. astaci and signal crayfish, while positive for noble crayfish eDNA.
  • In the Mosse watercourse, no eDNA of A. astaci and signal crayfish was detected, while noble crayfish eDNA was detected in Lake Våg.
  • In the Glomma watercourse, no sign of crayfish plague was found, and the samples were negative for all screened targets.
  • In Eidskog municipality, no samples were positive for signal crayfish or A. astaci, while several were positive for noble crayfish eDNA in the Vrangselva watercourse and River Finnsrudelva.

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