Grey seal numbers in the Wadden Sea continue to grow
Grey seal numbers in the Wadden Sea and on Helgoland continue to rise. In the 2025-2026 survey season, researchers counted 3,385 seal pups and 12,497 grey seals during the moulting season, confirming further population growth across the region. The results come from the latest report “Grey Seal Surveys of the Wadden Sea and Helgoland 2025-2026”, published under the Trilateral Cooperation on the Protection of the Wadden Sea.
Pup numbers increased by 11% compared to last year, reaching to 3,385 counted individuals and continuing a strong upward trend. Over the past five years, pup numbers have grown by an average of 12% annually. As in previous years, most of the pups were found in the Dutch part of the Wadden Sea (1,731), followed by Helgoland (1,077) and Lower Saxony (575), with a considerable increase in numbers recorded in Lower Saxony. In the eastern part of the Wadden Sea, only a few pups were observed during the main survey period, with one pup each in the Schleswig-Holstein and Danish parts of the Wadden Sea. The observation of a few additional pups later in the season confirm that pupping in this region occurs.
Adult grey seal counts during the 2026 moulting season showed an increase of 3.6% compared to 2025 and comprised a total of 12,497 animals. Most grey seals were counted in the Dutch part of the Wadden Sea (8,981). Numbers in the Schleswig-Holstein part of the Wadden Sea showed a notable increase, nearly doubling from 499 seals in 2025 to 957 in 2026. Counts in Denmark (348) also increased slightly, while numbers on Helgoland (989) and Lower Saxony (1,222) declined. Annual ups and downs can be affected by weather, disturbances, and other factors, making the overall Wadden Sea trends the most reliable indicator.
According to the trilateral Expert Group on Marine Mammals, with members from Denmark, Germany, and the Netherlands, the moult counts confirm the continued expansion of grey seals in the Wadden Sea towards the east. At the same time, many seals moulting in the area breed elsewhere. The later timing of births in the eastern Wadden Sea suggests that colonies are still developing.
Grey seals in the Wadden Sea are part of a larger, shared population. “Grey seals move widely across the North Sea, so these counts reflect both local animals and seals from other regions,” says the report’s lead author Jessica Schop of Wageningen Marine Research. “This highlights the importance of considering population dynamics at a broader scale and including observations of adjacent colonies in the annual evaluation of population development.” These include the Limfjord and Kattegat in the North, and the Dutch Delta area in the West.
Grey seals are the largest predators along the Wadden Sea coast and one of its most iconic species. Their population is monitored each year through international cooperation between Denmark, Germany and the Netherlands.