Cetaceans and pinnipeds, February – May 1991

The only cetacean which was reported frequently between 6 Feb and 4 May 1991 was the Harbour Porpoise Phocoena phocoena. Four animals were seen during seawatching (Hbz, 6 Feb (1) and 4 May (1), Bergen aan Zee 25 Feb (2), all Nil), the rest during surveys on board MV Navicula in coastal waters off the Dutch Wadden Sea islands (RH, MH, MK, ML, HO, MP, TP, CV). Most ani- mals were seen on 12 Mar (48) and 13 Mar (10) off Terschelling and off Schiermonnikoog (see map). Some 76 individuals were recorded, 33 sightings in all. Two larger aggregations on 12 Mar, of 29 and 12 individuals respectively, were found to consist of small units (herds 1, 1, 2, 2, 3, 4, 4, 4, 6, 6, 8 individuals), so average herd size was 2.3 ± 1.7 individuals. There was not one particular direction of movements; most porpoises were (slowly) swimming criss-cross. Sunbathing was recorded once.