Aerial surveys of Harbour Seals in the Wadden Sea in 2009: Growth of the harbour seal population slowing down?

• Main Authors: Sophie M.J.M. Brasseur, Peter J.H. Reijnders, Thomas Borchardt, Ursula Siebert, Germany Sven Ramdohr, Michael Stede, Lasse Fast Jensen, Jonas Teilmann
• Format: Report
• Language: English
• Published: Zenodo 2019
• Subjects: Biodiversity; Conservation; Monitoring; Scientific research; harbour seal
• Online Access: https://doi.org/10.5281/zenodo.8182299

In accordance with the Trilateral Seal Management Plan, the three Wadden Sea countries Denmark, Germany and the Netherlands perform harbour seal counts annually. These are coordinated and synchronised between the three countries. Five aerial counts are conducted nearly simultaneously every year at low tide from Esbjerg in Denmark to Den Helder in the Netherlands. This coordination allows for an estimate of the total population size and the number of pups born every year for the entire Wadden Sea. During these flights, all seals hauling out on sandbanks are counted. In 2009 the weather conditions during the pupping season in June and the moulting season in August were favourable during almost all the flights.