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Seal monitoring

The two seal species – harbour seal and grey seal – are flagship species in the Wadden Sea National Park. In early summer the pupping season and moult of harbour seals take place on sand banks in the inner Wadden Sea. In winter they are found on sand banks closer to the edge of the National Park, as they now increasingly hunt in the open North Sea. The pupping season of grey seals is in winter and in recent years their population has been growing steadily.

Since the foundation of the Wadden Sea National Park the seal population has regularly been monitored by aerial surveys. Since 1994 this effort is conducted in close coordination between the adjoining Wadden Sea National Parks and countries (Germany, the Netherlands and Denmark) within the framework of the trilateral monitoring and assessment programme (TMAP). The seals are protected by a seal treaty that has been ratified by the trilateral states and is binding under international law. Moreover, this monitoring effort is conducted to meet the requirements of the EU-FFH guideline.

In the years 2016 to 2020 BioConsult SH has been commissioned to conduct the aerial monitoring surveys in part of the Wadden Sea off the coast of Schleswig-Holstein by the ”Landesbetriebes für Küstenschutz, Nationalpark und Meeresschutz (LKN-Tönning)“. With five flights per year the seal populations are to be assessed. The flights are coordinated trilaterally and should yield numbers for the entire population as well as for the portion of this year’s young seals for each year, respectively.

2017 results

In August 2017, a total of 8,834 seals were counted in the Schleswig-Holstein Wadden Sea, a number exceeding the two values of the previous year. The number of animals is now as high as before the population decline between 2014 and 2016.

In 2017, pups made up a proportion of 30.7 %. This percentage confirms the trend observed in previous years and is generally increasing since the beginning of the 1990s despite year-to-year variation. In this year, the number of pups was the highest recorded in all parts of the Wadden Sea since the first surveys in 1975.

In the media

The Schleswig-Holstein Magazin of the NDR TV channel has reported several times about the project. The following report was broadcasted in June 2016.


During aerial surveys, all seal haul-out sites in the Schleswig-Holstein Wadden Sea are covered at low tide capturing digital photographs. The exact number of seals in these photographs is determined subsequently. In order to get a comprehensive picture of the seal population, surveys are conducted during the breeding season in June as well as during the annual moult in August.

grey seals

This picture shows seals of different ages. During the counting process the individuals are being marked differentially (males (here grey seals) = red dots; females (here grey seals) = blue dots; young (here harbour seal) = yellow dots). (The picture was taken on 15.04.2016. Click on picture to enlarge.)

grey seals A group of grey seals can be seen in this picture. A multitude of pictures is being taken during each aerial survey. The red line in this one indicates that the picture overlaps with another. Grey seals to the left of the line are being ignored in this image. (The picture was taken on 06.12.2016. Click on picture to enlarge.)

harbour seals

In this picture a group of harbour seals is shown on a sandbank with adults (red dots) and this year’s young (yellow dots). (The picture was taken on 15.06.2016. Click on picture to enlarge.)

harbour seals

Here adult seals (red dots) can be seen with this year’s young (yellow dots) on a sand bank. On either side of the image resting groups of Common eider ducks can be seen. (The picture was taken on 15.06.2016. Click on picture to enlarge.)


Thomas Grünkorn

Thomas Grünkorn