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 2020, eDNA of A. astaci was only detected in the southern part of Lake Rødnessjøen, and no spread of the pathogen was observed in any of the monitored areas.

  • In the control zone of the Halden watercourse, A. astaci eDNA was detected in the southern part of Lake Rødenessjøen. Here, the known presence of signal crayfish was also confirmed by positive eDNA detection. Within the control zone, A. astaci was not detected in any other of the stations. All water samples in the risk area of the Halden watercourse region were negative for eDNA from A. astaci and signal crayfish, while most samples were positive for noble crayfish eDNA.
  • In the Mosse watercourse, no eDNA of A. astaci or signal crayfish was detected, while noble crayfish eDNA was detected upstream of Lake Langen and in the River Tangenelva.
  • In the Glomma watercourse, there were no detection of eDNA from noble crayfish, nor from signal crayfish or A. astaci.
  • In Eidskog municipality, all samples were negative for both signal crayfish and A. astaci, while several samples were positive for noble crayfish eDNA in River Vrangselva and River Finnsrudelva.

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