Taxonomy & Nomenclature
Physical Description / Field Identification
White-beaked dolphins are extremely robust. The beak is short, set-off from the melon by a crease. The dorsal fin is tall and falcate, with a pointed tip. The color pattern is highly variable, but the animals are mostly black to dark gray. The beak and most of the belly are white to light gray, and the beak is often mottled. An area of light gra, originating on the upper flank, broadens to cover most of the tail stock. There is often dark or light flecking in the region between the eye and the flipper. Twenty-two to twenty-eight pairs of sharp teeth line each jaw. Adults are 2.4-3.1 m in length (males grow larger than females) and weigh between 180 and 300 kg.
Can be Confused With
White-beaked dolphins are most likely to be confused with Atlantic white-sided dolphins, from which they can be distinguished by differences in coloration and beak length. Also, in the few areas where they overlap with bottlenose dolphins, care must be taken to distinguish between these two.
Distribution
White-beaked dolphins inhabit cold temperate to subpolar oceanic waters of the North Atlantic. It is possible that two stocks exist, one in the eastern North Atlantic and the other in the western North Atlantic.
In the western North Atlantic, the range of white-beaked dolphins includes Cape Cod as its southern limit; the western Gulf of Maine; the Grand Banks; the coasts of Nova Scotia and Newfoundland; the Gulf of St. Lawrence; Davis Strait; and the coast of southeastern Newfoundland.
In the eastern North Atlantic, white-beaked dolphins are common around the Faeroe Islands and Iceland; are known in the Barents Sea from Svalbard and the Murman coast to portions of the coast (and in the fiords) of Norway; in the North Sea and waters of the United Kingdom; in the Skagerrak between Denmark and Norway as well as in the Kattegat between Denmark and Sweden; the approaches to the Baltic Sea; and south in the English Channel, the coast of France, the Bay of Biscay, and in rare instances the Portuguese coast and Straits of Gibraltar.
Ecology and Behavior
White-beaked dolphins inhabit shelf and slope waters. Groups of less than 50 white-beaked dolphins are most common, but herds of many hundreds have been seen. These animals are active, often leaping and breaching. While feeding, they sometimes associate with large whales.
There appears to be a calving peak in summer and early fall (June to September), but not much else is known about reproduction in this species. Newborns are between 1.2 and 1.6 m, and weigh approximately 40 kg.
Feeding and Prey
White-dolphins seize their prey, which consists of a broad diet dominated by: Fish > squid > other invertebrates. More specifically, white-beaked dolphins feed on variety of small schooling fishes, squid, and crustaceans. Cooperative feeding has been observed, in which groups drive prey into tight groups and push them to the surface.
Prey species include:
Fish: Gadus morhua, Melanogrammus aeglefinus, Trisopterus minutus, Trisopterus luscus, Merlangius merlangius, Merluccius merluccius, Mallotus villosus
Cephalopods: Eledone cirrhosa
Threats and Status
Main threats include:
• Harvest
• Fisheries bycatch
• Entanglement in debris/fishing gear
The IUCN does not list the white-beaked dolphin as endangered or threatened, nor does the United States government. Although not a target of any commercial fisheries, some dolphins are shot in Greenlandic waters. In addition, incidental catches in gill nets and trawl nets are known from several areas of the species’ range.
Links
References
Dong, J.H., J. Lien, D. Nelson and K. Curren. 1996. A contribution to the biology of the white-beaked dolphin, Lagenorhynchus albirostris, in waters off Newfoundland. Canadian Field-Naturalist 110:278-287.
Kinze, C.C. 2002. White-beaked dolphin Lagenorhynchus albirostris. pp. 1332-1134 in W.F. Perrin, B. Würsig and J.G.M. Thewissen, eds. Encyclopedia of marine mammals. Academic Press.
LeDuc, R.G., W.F. Perrin and A.E. Dizon. 1999. Phylogenetic relationships among the delphinid cetaceans based on full cytochrome b sequences. Marine Mammal Science 15:619-648.
Reeves, R.R., C. Smeenk, C.C. Kinze, R.L. Brownell, Jr. and J. Lien. 1999. White-beaked dolphin Lagenorhynchus albirostris Gray, 1846. pp. 1-30 in S.H. Ridgway and R. Harrison, eds. Handbook of marine mammals, Vol. 6: The second book of dolphins and the porpoises. Academic Press.
