Mesoplodon carlhubbsi Moore 1963

8.

Hubbs’s Beaked Whale

Mesoplodon carlhubbsi

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

Other common names: Arch-beaked Whale

Taxonomy. Mesoplodon carlhubbsi Moore, 1963,

“LaJolla, California, 32° 51° 41” N. Lat., 117° 15' 19° W. Long.”

This species is monotypic.

Distribution. Endemic to N Pacific Ocean, the majority ofrecords come from W North America from 32° 42° N to 54° 18’ N,also recorded on the Pacific coast ofJapan from 35% to 41° 42° N. This suggests that distribution of this species spans the N Pacific Ocean, but with no records from the C Pacific Ocean, it remains possible that there are separate E and W populations. It has been suggested that distribution of this species is related to the deep current system of the subarctic.

Descriptive notes. Total length 470-532 cm; weight ¢.1000-1500 kg (unconfirmed). Body of Hubbs’s Beaked Whale is spindle-shaped, with greatest girth around its mid-point. Flukes are wide in relation to body length, and tailstock is compressed laterally. Dorsal fin is small and set approximately two-thirds of the distance between tip of beak and end of the tail. Coloration is typically dark brown, dark gray, or black. Adult male Hubbs’s Beaked Whales have a white tip to their beak and a white patch posterior to the eye. Females andjuveniles may be paler on the ventral surface. Rostrum and lowerjaw form a short, poorly defined beak; there are two grooves on the throat. In adult males, lower jaw is slightly arched with a single tusk set on each side midway along its length. Adult males also may have many long, pale scars caused by tusks of other males during male-male combat.

Habitat. Thought to be restricted to water depths greater than 200 m, but there have been few confirmed sightings of Hubbs’s Beaked Whales at sea.

Food and Feeding. Little is known about diets of Hubbs’s Beaked Whales, but they seem to eat of deep-water squid. In common with other species of beaked whales, feeding likely occurs 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 of Hubbs’s Beaked Whales 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 for this species, but as with other species of Mesoplodon, Hubbs’s Beaked Whaleis likely to occur primarily in groups of five individuals orless.

Status and Conservation. CITES Appendix II. Classified as Data Deficient on The IUCN Red List. There are no estimates of global population size of Hubbs’s Beaked Whale. Like other species of beaked whales, Hubbs’s Beaked Whale may be at risk from a range of human activities, including noise pollution, bycatch from driftnet fisheries, and ingestion of plastic debris, and it also may be threatened by climate change. Nevertheless, nothing is known about the form or extent of these potential impacts.

Bibliography. Heyning (1984), Macleod, Perrin et al. (2006), MacLeod, Santos & Pierce (2003), Mead (1989b).