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According to the trilateral Seal Management Plan five coordinated
aerial surveys per year are required in order to monitor the Harbour
Seal population in the Danish, German and Dutch Wadden Sea.
In
2005, the total number of seals counted during the moult period in
August was 14,275. This number was comprised of 1,720 in Denmark,
5,505 in Schleswig-Holstein, 3,607 in Niedersachsen/Hamburg and
3,443 in The Netherlands. The maximum number of pups counted during
the whelping season in June was 4,507, in detail: Denmark 388,
Schleswig-Holstein 2,046, Niedersachsen/Hamburg 1,176 and The
Netherlands 897.
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This is
an apparent increase of 11.5% compared to 2004, and close to the
average annual growth rate of 12-13% observed in the pre-epizootic
period 1990-2001. As the increase from 2003 to 2004 was 18%, the
average growth rate observed so far after the epizootic in 2002 is
higher than before the epizootic. This corresponds to the remarkably
high ratio of pups versus total number of seals found over the last
three years. This ratio was 27-31% for the period 2003-2005,
respectively 20-25% for the period 1990-2001.
Elevated productivity may partly be explained by a female-biased
demography as a consequence of the 2002 mass die-off. Population
recovery to the pre-epizootic level may be expected by 2007/2008.
Trilateral Seal Expert Group (TSEG)
Svend Tougaard, Fiskeri- og Søfartmuseet, Esbjerg, Denmark
Kai F. Abt, Wildlife Consulting, Schleswig-Holstein, Germany
Sophie M.J.M. Brasseur, Alterra-Marine & Coastal Zone Research,
Texel, The Netherlands
Peter J.H. Reijnders, Alterra-Marine & Coastal Zone Research, Texel,
The Netherlands
Ursula
Siebert, FTZ-Büsum der Universität Kiel, Schleswig-Holstein, Germany
Michael Stede, LAVES Cuxhaven, Niedersachsen, Germany |
