1. National Institute of Seafood and Nutrition Research (NIFES), P.O. Box 2029 Nordnes, 5817 Bergen, Norway.
2. Norwegian School of Veterinary Science,
Department of Basic Sciences and Aquatic Medicine,
Aquaculture Protein Centre,
N-0033 Oslo,
Norway.
3. National Veterinary Institute, P.O. Box 750 Sentrum,
N-0106
Oslo, Norway.