Aerial surveys of grey seals in the Wadden Sea in the seasons of 2007-2008 and 2008-2009

After having been a common species along continental Europe in the Neolithic and early Bronze Age, grey seals Halichoerus grypus virtually disappeared from the Wadden Sea area. The species started to recolonise the Wadden Sea during the second half of the 20th century. Permanent colonies, were established in the 1960s off Amrum (Germany) and in the 1980s in the western part of the Dutch Wadden Sea. Regular surveys from boats have been carried out in The Netherlands since 1980 and off Amrum from 1988 onwards. From 2006 onwards, aerial surveys of grey seals were synchronized and coordinated trilaterally in the Wadden Sea. At present, two surveys are carried out during the moult (March-April). These are supplemented by several aerial or boat counts during the pupping season (November-January). In Helgoland (Germany), surveys are carried out from land. In the Danish Wadden Sea, grey seal numbers are rather low and therefore no dedicated surveys are carried out for grey seals. However, during the summer counts for harbour seals in the Danish Wadden Sea area in 2009 about 30 grey seals were observed.