Identification of the first harbour porpoise (Phocoena phocoena) calving ground in the North Sea

We investigated the occurrence of harbour porpoises in the North Sea off Sc hleswig-Holstein by conducting aerial surveys with emphasis on calves. Four teen per cent of the sighted porpoises off the islands of Sylt, Amrum and s outhern Romo were calves, whereas the average calf proportion for the whole North Sea as established during the 1994 SCANS survey was only 5.4%. The s ignificantly higher proportion of calves off Sylt and Armum indicates that these coastal waters are used as a preferred calving ground for harbour por poises. Analysis of stranding data showed that the identified calving groun d does not extend south of Amrum and that harbour porpoise calves are prese nt off Sylt and Amrum all year round. The combination of sighting and stran ding data demonstrates the special importance of the investigated area for harbour porpoises as a calving and nursing ground. The area should therefor e be protected. (C) 1999 Elsevier Science B.V. All rights reserved.