Grey Seal Numbers in the Wadden Sea and on Helgoland in 2021-2022

Expert Group Marine Mammals

Since 2008, annual coordinated aerial surveys have been conducted to monitor the number of grey seals in the Wadden Sea, covering the sandbanks in Denmark, Germany and the Netherlands. Additional land-based counts were conducted on Helgoland, an offshore island in the German Bight. In the pupping season, between November and January, grey seal pups are counted, providing information on the development of the local breeding population. In March and April, the seals are counted during moult, which provides information on the number of grey seals using the Wadden Sea and Helgoland. The grey seals in this area are part of a larger population in the North Sea, including the United Kingdom. Migrating animals are likely to influence the trilateral counts during the moult (Brasseur et al. 2015). The counted numbers represent an index, which can be used to show relative changes in the abundance of grey seals in the different Wadden Sea areas. Trends should be considered over several years, as annual changes could be influenced, for example, by the weather.

This report was published 2022-07-01.

This report should be cites as: Schop J., Abel C., Brasseur S., Galatius A., Jeß A., Meise K., Meyer J., van Neer A., Stejskal O., Siebert U., Teilmann J., Thøstesen C. B. (2022) Grey Seal Numbers in the Wadden Sea and on Helgoland in 2021-2022. Common Wadden Sea Secretariat, Wilhelmshaven, Germany.