1. University of Gothenburg, Department of Biological and Environmental Sciences, Box 463, SE-405 30 Gothenburg, Sweden.
2. Technical University of Denmark (DTU), National Institute of Aquatic Resources, Vejlsøvej 39, DK-8600 Silkeborg, Denmark.
3. Danish Centre for Wild Salmon, Brusgårdsvej 15, DK-8960 Randers SØ, Denmark.