Food and feeding ecology of the striped dolphin, Stenella coeruleoalba, in the oceanic waters of the north-east Atlantic

Abstract

The food and feeding ecology of the striped dolphin, Stenella coeruleoalba, in the oceanic waters of the north-east Atlantic were studied using the stomach contents of 60 striped dolphins caught in the albacore drift-net fishery throughout the summer months of 1992 and 1993 off the Bay of Biscay. Thirty-eight per cent of these dolphins were calves (0–1 years old), 25% were juveniles (2–8) and 37% were mature adults (9–32, of which 7 females and 14 males). The diet was found to be primarily composed of fish (39% by mass (M)) and cephalopods (56% M) and secondarily of crustaceans (5% M). The most significant fish family identified was the lanternfish (24% M) with Notoscopelus kroeyeri and Lobianchia gemellarii being predominant. Among squid, the oceanic Teuthowenia megalops and Histioteuthis spp. were the most significant. The pelagic shrimp Sergastes arcticus and Pasiphaea multidentata were the most prevalent crustaceans. Prey sizes ranging from 30 to 170 mm accounted for 80% of the prey items while 80% of the reconstituted biomass consisted of prey measuring between 60 and 270 mm. Prey composition and size-range differed slightly with sex and age or body size of the dolphins. The state of digestion of food remains suggested that predation took place at dusk or during the early hours of the night on which the dolphins were caught.