[1] Univ Islas Baleares, CSIC, Inst Mediterraneo Estudios Avanzados, Esporles, Spain
[2] Univ So Denmark, Inst Biol, Odense, Denmark
[3] Norwegian Univ Sci & Technol, Dept Biol, N-7034 Trondheim, Norway
[4] FAO Fisheries Dept, Inland Water Resources & Aquaculture Serv, Rome, Italy
[5] Dunstaffnage Marine Lab, Scottish Assoc Marine Sci, Dept Ecol, Oban, Argyll, Scotland
[6] Univ Crete, Dept Biol, Iraklion, Greece