Wadden Sea harbour seals bear more pups than ever

The Wadden Sea harbour seal population remains stable, with 25,000-27,000 individuals counted yearly since 2012. 2018 has been yet another record year for pups, registering the highest count since 1975 with a total of 9,285 observed new-borns. These are the main findings of the report “Aerial surveys of Harbour Seals in the Wadden Sea in 2018”, published by the Trilateral Seal Expert Group (TSEG) of the Trilateral Wadden Sea Cooperation and based on trilaterally coordinated surveys in the Danish, Dutch and German parts of the Wadden Sea World Heritage site.


In order to observe both adult harbour seals and pups, the TSEG conducts its trilateral counts twice each year: total numbers of harbour seals are generally counted during the moulting season, when they spend substantially more time on land, while new-borns are monitored during pupping season. During the moult in August 2018, 2,675 seals were counted in Denmark (-10% compared to 2017) and 8,058 in Lower Saxony and Hamburg (+10% from 2017). The trends in numbers may be the result of a change in the survey date, varying numbers of seals hauling out, or a shift in the spatial distribution of seals over time. Due to military activities an area in the Netherlands was closed off for surveys, leading to only a partial count of 6,774 individuals. Schleswig-Holstein could not be surveyed due to unfavourable weather conditions on the survey days. If counts of 2017 were used for Schleswig-Holstein (8,834) and the Netherlands (adding 1,151 for the area that was not surveyed in 2018) the estimated total number of counted harbour seals in the Wadden Sea would be 27,492. Keeping in mind that not all seals are on land at any given time, the seal experts added a correction factor to this number and gave an estimation of a total population size of harbour seals in the Wadden Sea of about 40,000 in 2018.

Full article can be found at waddensea-secretariat.org

The full Harbour Seal Report is available as a pdf here