Results from a Pilot-Study on sightings of Harbor Porpoises, Phocoena-Phocoena, at the North-Sea Coast of Schleswig-Holstein, Frg

H. Kremer, L. Koch, B. Adloff, B. Baschek, O. Schneider, and W. Fischer

Archive of Fishery and Marine Research 42 (1): 35-45, 1994

The number of sightings of harbour porpoises, Phocoena phocoena, along the west coast of Schleswig-Holstein is described. This information has been continuously gathered from returns of data sheets that were made available at numerous information centres in the area of the Wadden Sea. Between November 1988 and December 1990, 330 sighting events comprising a total of 758 individuals were recorded. 87.6% of the observations were reported from the west coast of the Isle of Sylt. Group size ranged from 1 to 30 individuals, 46.1% of all observations referred to single animals. Relationships between the number of sightings and local tide were investigated and a model fitted. In contrast to seasonal variations in observer effort, a summer-peak in stranding-records and assumed inshore-movements of harbour porpoises during summer, the number of sightings in the present study peaked in late autumn. The collected data may be interpreted as an indication of a seasonal increase in harbour porpoises, at least in the years 1989/90, at the west coast of Schleswig-Holstein, especially near the Isle of Sylt. Possible reasons for this development are discussed.