Affiliation: | 1. Sea Mammal Research Company (SEAMARCO) , Julianalaan 46, 3843 CC , Harderwijk , The Netherlands E-mail: Researchteam@zonnet.nl;2. TNO Observation Systems , P.O. Box 96864, 2509JG , Den Haag , The Netherlands E-mail: wcverboom@hotmail.com;3. Wageningen IMARES (Institute for Marine Resources &4. Ecosystem Studies) , P.O. Box 68, 1970 , AB , IJmuiden , The Netherlands E-mail: Dick.deHaan@wur.nl;5. IMARES Texel , P.O. Box 167, 1790 AD Den Burg , Texel , The Netherlands E-mail: Peter.Reijnders@wur.nl |