Mesoplodon bowdoini, Andrews, 1908

Russell A. Mittermeier & Don E. Wilson, 2014, Ziphiidae, Handbook of the Mammals of the World – Volume 4 Sea Mammals, Barcelona: Lynx Edicions, pp. 326-357 : 356-357

20.

Andrews’s Beaked Whale

Mesoplodon bowdoini

French: Baleine-a-bec d Andrews / German: Andrews-Zweizahnwal / Spanish: Zifio de Andrews

Other common names: Splaytooth Beaked Whale

Taxonomy. Mesoplodon bowdoini Andrews, 1908 ,

“collected at New Brighton Beach, Canterbury Province, New Zealand.”

This species is monotypic.

Distribution. Poorly known, but it appears to be restricted to cooler waters of the Southern Hemisphere between 32° S and the Antarctic convergence; it has been recorded stranding in New Zealand, Australia, Tristan da Cunha, and Tierra del Fuego. Its distribution may be circumpolar, but it is also possible that there is a gap in its distribution between the Chatham Is and South America.

Descriptive notes. Total length 390-441 cm; weight ¢.1000 kg (unconfirmed). Body of Andrews’s Beaked Whale is spindle-shaped, with greatest girth around its midpoint. Flukes are wide in relation to body length, and tailstock is compressed laterally. Dorsal fin is small and set approximately two-thirds the distance between tip of the beak and end ofthe tail. Coloration is typically dark brown, dark gray, or black. There are two grooves on the throat, and rostrum and lower jaw form a short, poorly defined beak.

In adult males, tip of the beak is white, and lower jaw is slightly arched, with a single tusk on each side midway along its length. Males may also have many long pale scars that are caused by tusks of other males during male-male combat.

Habitat. Presumably restricted to water depths greater than 200 m, but there have been few confirmed sightings of Andrews’s Beaked Whale at sea. This habitat preference is based on inferences from other related species of beaked whales.

Food and Feeding. Little is known of the diet of Andrews’s Beaked Whale, but it is assumed that, as with other species of Mesoplodon , it primarily consumes deep-water squid and deep-water fish. In common with other species of beaked whales, feeding is likely to occur at great depth, often over 500 m and possibly as deep as 3000 m or more. Foraging dives may be up to an hour in length.

Breeding. There is no specific information available for this species, but it is assumed that tusks are used during aggressive interactions between males, presumably over females.

Activity patterns. There is no information available for this species.

Movements, Home range and Social organization. There is no specific information available forthis species, but as with other species of Mesoplodon ,it likely occurs in small groupsoffive or fewer individuals.

Status and Conservation. CITES Appendix II. Classified as Data Deficient on The [UCN Red List. There are no estimates of global population size of Andrews’s Beaked Whale. It is not known whether lack of confirmed sightings means that it is genuinely rare, or whetherit is just difficult to detect and identify with any level of accuracy. Like other species of beaked whales, Andrews’s Beaked Whale may be at risk from a range of human activities including climate change, noise pollution, bycatch, and ingestion of plastic debris. Nevertheless, nothing is known about the form or extent of these potential impacts.

Bibliography. Baker (2001), MacLeod et al. (2006), Mead (1989b).

Figures

On following pages: 18. Sowery's Beaked Whale (Mesoplodon bidens); 19. Blainville’s Beaked Whale (Mesoplodon densirostris); 20. Andrews's Beaked Whale (Mesoplodon bowdoini); 21. Spade-toothed Whale (Mesoplodon traversil); 22. Gervais's Beaked Whale (Mesoplodon europaeus).

Distribution. Poorly known, but it appears to be restricted to cooler waters of the Southern Hemisphere between 32° S and the Antarctic convergence; it has been recorded stranding in New Zealand, Australia, Tristan da Cunha, and Tierra del Fuego. Its distribution may be circumpolar, but it is also possible that there is a gap in its distribution between the Chatham Is and South America.