1. Baltic Sea Research Institute, Seestrasse 15, D-18119 Warnemünde, Germany
2. Danish Institute for Fisheries Research, Charlottenlund Castle, DK-2920 Charlottenlund, Denmark
3. Latvian Fisheries Research Agency, Daugavgrivas Street 8, LV-1007 Riga, Latvia
4. Bundesamt für Seeschifffahrt und Hydrographie, Bernhard-Nocht-Strasse 78, D-20359 Hamburg, Germany