Cuvier's Beaked Whale

Cuvier's Beaked Whale has a wide distribution and has been observed at sea more often than many other beaked whale species.

Identification

Cuvier's Beaked Whale was described from a skull by Georges Cuvier in 1823, who mistakenly identified it as an extinct fossil species, because the skull looked 'petrified'. As with other beaked whales, most of the knowledge of this species comes from stranded animals. Some information has been gathered from Japanese fisheries.

Adults may be slate-grey to reddish-brown or purplish-black. Adult males have whitish heads and carry many long, linear tooth-rake scars, probably inflicted by other males of the same species. The white dorsal pigmentation may extend back toward the dorsal fin and become more distinct with age. This lighter head colouration is less pronounced in females, although the beak and throat may be almost white. Regional variation in colour pattern is possible. Animals of both sexes may have dark 'eye patches'. Animals of both sexes may also have white circular scars, that are probably cookie-cutter shark bites. The body is robust and spindle-shaped. The head of Cuvier's Beaked Whale is short and blunt, with a gently sloping forehead, a small, poorly defined beak, and an indistinct melon. The blunt beak distinguishes this whale from all other beaked whales; its appearance in profile led to the common name 'Goose-beaked Whale'. The mouth curves upwards in a 'smile'. Adult males have a pair of cylindrical teeth at the tip of the lower jaw. These teeth project forwards and protrude beyond the upper jaw. These teeth do not erupt in females. There may be (rarely) up to 34 vestigial teeth in the gums of the upper jaw. The sickle-shaped dorsal fin is positioned about two-thirds of the distance from the beak to the tail. The flippers are small and narrow with rounded tips, and, when at rest, sit in shallow depressions in the body wall. The flukes are broad; their width may be up to one quarter the length of the body.

Cuvier's Beaked Whales have often been observed in small groups of up to about seven animals, although solitary animals, and larger groups of about 25 animals, have also been reported. At the surface they swim with a lurching motion, often exposing the top of the head. The flukes can sometimes be seen as the animal dives. The blow is low, inconspicuous, and directed forwards.

Cuvier's Beaked Whales can be readily identified by their sloping foreheads, short stubby beak, pale head, and the exposed teeth of males.

Distribution

Cuvier's Beaked Whales are widely distributed in tropical to subpolar waters. They have not been recorded from polar seas. They are most commonly found in waters exceeding 1000m in depth. They usually occur far from continental landmasses, to as far south as 54°S in the Southern Hemisphere. There have been many strandings of this whale throughout Australia and in parts of New Zealand. The large number of strandings that have taken place throughout its range suggests that Cuvier's Beaked Whales are not uncommon.

Feeding and diet

Very little is known about the diet of Cuvier's Beaked Whales. Examination of a small number of stomach contents revealed mainly squid and fish. Most prey species were either open ocean, mesopelagic, or deep-water benthic animals, supporting other evidence that this is an offshore deep-diving species. Because they lack functional teeth, they presumably capture most of their prey by suction.

Life history cycle

The extensive linear scarring seen on adult males of this (and most other beaked whale) species is probably due to within-species combat with other males. Little is known about the breeding habits of this species. Based on information from the Japanese fishery, both males and females may become sexually mature at around 5.0-5.5m in length. The average length at birth is 2.7m, but the time of year for calving is not known with certainty.

Conversation status

Cuvier's Beaked Whales were taken opportunistically along the Japanese coast as part of the hunt for the larger Baird's Beaked Whale. Up to the early 1970s, 3-35 animals were taken annually. There has been no reported commercial capture of Cuvier's Beaked Whales in recent years. However, meat from this species has been found for sale on the commercial markets of both Japan and the Republic of (South) Korea. This suggests that this species may still be taken accidentally as fisheries bycatch or suffer from undocumented hunting in this region. Small numbers have also been taken in the Lesser Antilles, Indonesia, Peru and Chile, or taken accidentally as fisheries bycatch in a number of areas. They appear vulnerable to noise: several recent mass strandings have been attributed to military activities using sonar weapons.

References

• Baker, A. N. 1999. Whales and Dolphins of Australia and New Zealand: an identification guide. Allen & Unwin, St Leonards.
• Bryden, M., Marsh, H. & Shaughnessy, P. 1998. Dugongs, Whales, Dolphins and Seals. A guide to the sea mammals of Australasia. Allen & Unwin, St Leonards.
• Carwardine, M. 2000. Whales, Dolphins and Porpoises. Dorling Kindersley, London.
• Dalebout, M. L., van Helden, A. van Waerebeek, K, and Baker, C. S. 1998. Molecular genetic identification of Southern Hemisphere beaked whales. Molecular Ecology 7: 687-694.
• Heyning, J. E. 1989. Chapter 11. Cuvier's beaked whale Ziphius cavirostris G. Cuvier, 1823. In Handbook of Marine Mammals. Pp. 289-308. (Eds S. H. Ridgeway and S. R. Harrison.) Academic Press, London.
• Menkhorst, P. 2001. A Field Guide to Mammals of Australia. Oxford University Press, Melbourne, Australia.
• Reeves, R. R., Stewart, B. S., Clapham, P. J. and Powell, J. A. 2002. Cuvier's Beaked Whale. In National Audubon Society Guide to Marine Mammals of the World. Pp. 254-255. Chanticleer Press, Inc., New York.