Monitoring van gewone en grijze zeehonden in de Nederlandse Waddenzee, 2002-2017

Samenvatting

Harbour seal (Phoca vitulina) and grey seal (Halichoerus grypus) in the Wadden Sea are surveyed each year to support the international management of and policies for both populations. This annual census has been carried out for the Ministry of Agriculture, Nature and Food Quality by Wageningen Marine Research (WMR) since 1960. The results show that the growth in the harbour seal population is flattening off while the counted numbers of grey seal are still rising. Differences in the trend in numbers counted between sub-areas of the Dutch Wadden Sea have been observed for both seal species. The preferred haul-out sites also differ between the breeding season and moulting period. Further research will be needed to show which factors influence numbers and choice of haul-out site, and how these factors affect population size