Mesoplodon europaeus, Gervais, 1855

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 : 357

22.

Gervais’s Beaked Whale

Mesoplodon europaeus

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

Other common names: European Beaked Whale, Gulf Stream Beaked Whale

Taxonomy. Diophlodon europaeus Gervais, 1855 ,

English Channel, “qui provient d’un individu harponné dans la Manche.”

This species is monotypic.

Distribution. Endemic to subtropical and tropical waters of the Atlantic Ocean in an area ranging from N USA to Brazil and from Ireland to Guinea-Bissau; its distribution may continue as far S as Uruguay in the W, and possibly as far S as Angola in the E. It is occasionally recorded stranding in temperate waters, but these may represent vagrant individuals.

Descriptive notes. Total length 420-485 cm; weight ¢.800 kg (unconfirmed). Gervais’s Beaked Whale is one of the few species of beaked whales where females are larger than males, although this difference is relatively small: females are only 6% longer than males. Body 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 of the tail. Coloration is typically dark brown, dark gray, or black and paler underneath. There may be a white patch around the genitalslit in some adult females. Rostrum and lower jaw form a beak thatis indistinct from the low, sloping forehead. There are two grooves on the throat. Adult male Gervais’s Beaked Whales have a single triangular tusk on each side of the lower jaw. Tusks are positioned close to but not at tip of mandible. Adult males may have long, linear pale scars on their backs that are caused by tusks of other males during male-male combat.

Habitat. Primarily waters greater than 200 m deep. Occurrence of Gervais’s Beaked Whale may be linked to areas of complex seabed topography.

Food and Feeding. Little is known about the diet of Gervais’s Beaked Whales. In common with other species of beaked whales, they are thought to consume deep-water squid and,to a lesser extent, deep-water fish. They may also be one of the few species of beaked-whales that commonly consume deep-water crustaceans.

Breeding. Almost nothing is known about the reproductive biology of Gervais’s Beaked Whale. Females give birth to a single offspring after gestation that is likely twelve months. Offspring are likely dependent on their mothers for at least one year. Individuals may live as long as 48 years.

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

Movements, Home range and Social organization. There is no specific information available for this species, but they are known to occur in small groups that typically consist of fewer than five individuals. Nothing is known about the typical composition of these groups.

Status and Conservation. CITES Appendix II. Classified as Data Deficient on The [UCN Red List. There are no estimates of global population size of Gervais’s Beaked Whale. Like other species of beaked whales, Gervais’s Beaked Whale is potentially affected by ingestion of plastic debris and noise pollution, and it may be caught as bycatch in driftnet fisheries. Nevertheless, nothing is known about the form or extent of these potential impacts.

Bibliography. Macleod (2006), MacLeod & D'Amico (2006), MacLeod et al. (2006), Mead (1989b), Norman & Mead (2001).

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. Endemic to subtropical and tropical waters of the Atlantic Ocean in an area ranging from N USA to Brazil and from Ireland to Guinea-Bissau; its distribution may continue as far S as Uruguay in the W, and possibly as far S as Angola in the E. It is occasionally recorded stranding in temperate waters, but these may represent vagrant individuals.