Grey Seal Numbers in the Wadden Sea and on Helgoland in 2023-2024

Expert Group Marine Mammals

Since 2008, annual coordinated surveys have been conducted to count grey seals on sandbanks in the Wadden Sea and Helgoland across the Netherlands, Germany, and Denmark. Grey seal pups are counted during the pupping season from November to January and the overall numbers of grey seals are counted during the moulting season in March and April. To ensure more precise trend analysis, we use the dates with the largest numbers of grey seals counted within the shortest possible timeframe across the Wadden Sea. This minimises the chance of double-counting individuals moving between haul out sites. Aerial surveys covered all survey areas except for Helgoland, where land-based counts were conducted during the grey seal moult.

This report was published 01.07.2024.

This report should be cites as: Schop J., Brasseur S., Galatius A., Hamm T., Jeß A., Meise K., Meyer J., Stejskal O., Siebert U., Teilmann J., Thøstesen C. B. (2024) Grey Seal Numbers in the Wadden Sea and on Helgoland in 2023-2024. Common Wadden Sea Secretariat, Wilhelmshaven, Germany.