White-Beaked Dolphin: Lagenorhynchus albirostris

Abstract

This chapter focuses on white-beaked dolphins, which were among the last of the commonly occurring North Atlantic dolphin species to enter the cetological theater. The white-beaked dolphin has a robust appearance. The beak is only 5–8 cm long and there is an erect falcate dorsal fin on the middle of the back. Adults grow to between 2.4 and 3.1 m long and may weigh between 180 and 360 kg. Males usually grow larger than females. Newborn animals are about 1.2 m long and weigh approximately 40 kg. The coloration is typically black on the back with a white saddle behind the dorsal fin and whitish bands on the flanks that vary in intensity from shining white to light gray. The belly and the beak normally are white and the beak sometimes is ashy gray or even darker, but never all black. The belly may also exhibit a grayish coloration, leaving only a median narrow band of pure white. Younger animals may exhibit generally a lighter coloration. The whitish bands on the flank fade shortly after the death of the animal. The blubber thickness varies between 20 and 35 mm. The total blubber weight amounts to between 20% and 30% of the total weight, with the highest figures found in pregnant females. The diet of the species seems to reflect the local abundance and availability of certain prey species and therefore geographical differences exist. In Danish waters, cod and other gadid fish were found to be the main prey items. Analyses from Scottish waters showed that white-beaked dolphins in addition also consume cephalopods.