Cetaceans and pinnipeds, September – November 1991

Only data from ship-based surveys and seawatching were received in time. Most cetaceans were seen off the Scottish and English east coast, including solitary Minke Whales Balaneoptera acutorostrata (4x), and small herds of White-beaked Dolphins Lagenorhynchus albirostris (9x), White-sided Dolphin Lagenorhynchus acutus (2x), and Harbour Porpoise Phocoena phocoena (17x; figure 1). On 10 September, 25 White-beaked Dolphins were seen breaching at 54°25’N, 00°27’E, with 10 ’patterned’ dolphins (squares in figure 1) behaving just so on great distance from the ship (PD, JH). The next day, 4 White-sided Dolphins were seen breaching further to the north (55°00’N, 00°30’W). Minke Whales seen in these waters were sometimes seen close to fishing trawlers. The herringfleet was working at about 54°30’N, 01°00’E, in waters with Minke Whales, Harbour Porpoises and massive numbers of seabirds. White-beaked Dolphins were often seen at the bow of MV Tridens, or behind the ship during trawling (PD, JH, ML, HB). Of a mixed group of 4 White-sided and 2 White-beaked Dolphins (with 40 associated Gannets), only the White-beaked Dolphins came to the bow, while the first species stayed at least 500m away from the ship. 26 Harbour Porpoises were seen in flat calm conditions between 54°N, 01°20’E and 53°35’N, 01°27’E (figure 1). The average herd size of Harbour Porpoises off East Britain was 2.7 ± 1.4 (n= 17 sightings, 46 individuals). Rather strong winds prevailed during most of the surveys this autumn, otherwise, without doubt, the number of cetaceans seen had been considerably larger. Coastal sightings included a single Harbour Porpoise in Den Helder, 19 October (EG), and Schiermonnikoog, 12 October 1991 (WvS). White-beaked Dolphins were seen twice in the SE North Sea: 3 on 22 October at 53°48’N, 05°53.5’E (RH, HO), and a possible sighting (1 at the bow) on 30 October at 55°44’N, 04°38’E (BB, TG).