Common Wadden Sea Secretariat
The coordinated aerial, boat and land surveys of the Dutch, German and Danish Wadden Sea areas and Helgoland (Germany) aim to record annual changes in numbers of grey seals (Halichoerus grypus). The numbers of pups born in winter are indicative of changes in the local breeding population, while the total counts during the moulting season in spring include animals that might have bred elsewhere and have redistributed during the post breeding period. Results of the counts do not yield an absolute or maximum number of seals, but a number that can be compared from year to year to establish statistical trends in the population size and development.
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