RESULTS FROM A PILOT-STUDY ON SIGHTINGS OF HARBOR PORPOISES, PHOCOENA-PHOCOENA, AT THE NORTH-SEA COAST OF SCHLESWIG-HOLSTEIN, FRG

The number of sightings of harbour porpoises, Phocoena phocoena, along the west coast of Schleswig-Holstein is described. This information h as been continuously gathered from returns of data sheets that were ma de available at numerous information centres in the area of the Wadden Sea. Between November 1988 and December 1990, 330 sighting events com prising a total of 758 individuals were recorded. 87.6% of the observa tions were reported from the west coast of the Isle of Sylt. Group siz e ranged from 1 to 30 individuals, 46.1% of all observations referred to single animals. Relationships between the number of sightings and l ocal tide were investigated and a model fitted. In contrast to seasona l variations in observer effort, a summer-peak in stranding-records an d assumed inshore-movements of harbour porpoises during summer, the nu mber of sightings in the present study peaked in late autumn. The coll ected 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 rea sons for this development are discussed.