1Department of Marine Biotechnology, Norwegian College of Fishery Science, University of Tromsø, N-9037 Tromsø, Norway
2Friedrich-Loeffler-Institute, Federal Research Institute for Animal Health, 17493 Greifswald-Insel Riems, Germany
3Inland Station/National Research Institute of Aquaculture, Fisheries Research Agency, Tamaki, Mie 519-0423, Japan