Mesoplodon carlhubbsi

Hubbs’s beaked whale is another little-known species. Beaks of squids and otoliths (inner ear particles) of some deepwater fish, some of which could have come from the stomachs of the squids, were found in the stomachs of a few stranded individuals in California. Scars on the skin have been noted, and may be evidence that males fight each other. The jaws of this species may be adapted to fighting: they are made of very compact bone, denser than any other mammalian tissues, including teeth. In North American populations, females are thought to calve in mid-summer, but little is known about reproduction in this species.

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Mammal Species of the World

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Unknown

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Apparently limited to the North Pacific Ocean, Hubbs' beaked whale is known from central British Columbia to southern California in the east, and from Japan (including the Sea of Japan) in the west (Mead 1989; MacLeod et al. 2006). Although the vast majority of records are of strandings, sightings have been made off the coast of Oregon and Washington (Mead et al. 1982, Heyning 1984). This is an oceanic species, and the range is thought to be continuous across the North Pacific, although this is not confirmed (MacLeod et al. 2006).

Mesoplodon carlhubbsi, or Hubb’s beaked whale, is found in the temperate waters of the North Pacific. M. carlhubbsi ranges from Japan to British Columbia and California. The northernmost sighting occurred in Eastern North Pacific, near Prince Rupert, British Columbia. The southernmost record occurred southwest of San Clemente Island, California. Here, a rostral portion of a skull was found by the submersible “Deep Sea.”

Biogeographic Regions: pacific ocean (Native )

North Pacific

occurs (regularly, as a native taxon) in multiple nations

Global Range: Cold temperate North Pacific Ocean, extending in the eastern Pacific roughly from San Diego, California, to Vancouver Island, Canada (based on stranding records) (Leatherwood and Reeves 1983); occurs off Japan in the western Pacific (IUCN 1991).

Generally, the whales in the genus Mesoplodon are small. The maximum adult length ranges from 4.3 meters to 6.15 meters. Males of this species can reach a maximum weight of 1500 kg. These whales have relatively small heads, large thoraxes and abdomens, and short tails (as compared to other toothed whales).

Mesoplodon species also have a pair of throat grooves. These are found on the ventral side of the head between the lower jaws. A notch occurs in the center of the flukes. The flipper has a short phalangeal portion. This is typical of the family Ziphiidae. The dorsal fin is small and sub-triangular. It is positioned about two-thirds of the way back on the animal.

Adult male M. carlhubbsi are usually dark gray to black except for two white patches on the head. One patch covers the tip of the rostrum and lower jaw back to the posterior border of the teeth. The other patch occurs in a roughly circular pattern, about 30 centimeters in diameter, centered around the blowhole.

The functional teeth in males are large and straight-sided. They are located near the middle of the mouth. These remain exposed when the mouth is closed.

Adult female M. carlhubbsi are usually medium-gray on the dorsal surface of their bodies. Their sides are a lighter shade of gray. The belly is white. Also, the area of the body just posterior to the flipper, termed the flipper pocket, is darker in color than the surrounding body. The front half of the rostrum and lower jaw are lighter in color than the rest of the head.

The functional teeth of females are smaller than those of the males. They often don’t erupt above the gums.

In both sexes of M. carlhubbsi, the bottom side of the flukes is lighter than the top side. They also have concentric striations that radiate anteriorly from the terminal caudal vertebrae.

Range mass: 1500 (high) kg.

Average mass: 1500 kg.

Range length: 4.3 to 6.15 m.

Sexual Dimorphism: sexes colored or patterned differently; male more colorful

Length: 500 cm

Length:
Range: up to 5.3 m

Weight:
Average: 1,432 kg

Habitat and Ecology

Systems

• Marine

M. carlhubbsi seems to prefer deep water far from shore. Their typical habitat is the deep, subarctic current system.

Habitat Regions: temperate ; polar ; saltwater or marine

Aquatic Biomes: pelagic

oceanic

Habitat Type: Marine

Comments: Pelagic.

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

The diet of M. carlhubbsi includes squid, other cephalopods, and fish. According to Ridgway and Harrison (1989), it is believed that M. carlhubbsi feeds mainly on squid, which is characteristic of beaked whales. However, all information is based on stranded animals. It is possible that the stranded individuals might not be representative of the whole population.

Animal Foods: fish; mollusks

Primary Diet: carnivore (Piscivore , Molluscivore )

Comments: Recorded stomach contents include various squids and mesopelagic fishes.

No information has been found regarding the ecosystem roles of M. carlhubbsi. However, it is likely that as large marine predators, these whales have some regulating influence on their prey populations, primarily fish and squid.

No information has been found regarding predation in M. carlhubbsi.

Mesoplodon carlhubbsi preys on:
Actinopterygii
Mollusca

This list may not be complete but is based on published studies.

Most odontocete whistles are narrowband sounds. The frequency pattern can be unmodulated, trilled, ascending, descending, ascending-descending, descending-ascending, or slowly wavering. A whistle can consist of one of these sound patterns that is given once or repeated. It can also consist of a series of sounds of several types. The amplitudes of the ascending and descending portions can vary over the duration of a whistle. Whistles can have a varying number of breaks and segments in one whistle or be continuous. The initial, final, maximum and minimum frequencies, as well as the duration and level, may vary for any one species.

M. carlhubbsi produces pulses and whistles to communicate. Their typical frequency range for pulses are 0.3-2, 0.3-80+ kHz, with the dominant frequencies occurring in the range of 0.3-2 kHz. The typical frequency range for whistles is 2.6-10.7 kHz.

In addition to vocal communication, it is likely that M. carlhubbsi, like other mammals, uses both visual and tactile signals.

Communication Channels: visual ; tactile ; acoustic

Perception Channels: visual ; acoustic

There is not much data available on the development of Mesoplodon carlhubbsi. The mean length at birth is estimated to be 2.50 meters for M. carlhubbsi. However, this is based on extrapolation as 40-48% of the maximum reported length of females in the species. (Ridgway 1989). M. carlhubbsi can reach a maximum length of about 530 cm along with an average of about 1500 kg. (Nowak 1991).

No data has been found regarding the lifespan, or longevity, of M. carlhubbsi. This paucity of data is common for the genus.

The mating system of these whales has not been characterized in the literature.

There is not much data available on reproduction in M. carlhubbsi. Birth usually occurs during the summer, after a twelve month gestation. According to Reynolds and Rommel (1999), “The timing of events in the reproductive cycle for all cetaceans is clearly geared to optimize the seasonal changes in environmental conditions to benefit the ecology of the species and favor maximal survival of the young."

The litter size is most likely one offspring per birth in the entire genus Mesoplodon. Young are likely precocial, and able to follow the mother from birth.

There are no data available on the timing of weaning, independence, or reproductive maturity for this species.

Breeding interval: The breeding interval for these whales is unknown, but is certainly no more than once per year.

Breeding season: Breeding probably occurs in the summer.

Average number of offspring: 1.

Average gestation period: 12 months.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization (Internal ); viviparous

Young are most likely precocial and able to follow their mother through the water from birth. As in all mammals, the mother provides milk for the developing young, although the period of nursing in this species is not known. It is not known what role males may play in parental care.

Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)

Births occur apparently in early summer.

Canada

Rounded National Status Rank: NU - Unrankable

United States

Rounded National Status Rank: N2 - Imperiled

Year Assessed

Assessor/s

Reviewer/s

Justification

History

• 1996
  Data Deficient
• 1994
  Insufficiently Known
  (Groombridge 1994)

It is difficult to evaluate the population size of species like M. carlhubbsi, because they occur far from shore, and because they are not very conspicuous animals. Although they are sighted infrequently, as are most members of the genus, it is difficult to tell whether the low incidence of sightings is due to rarity of animals, or is simply an artifact of their unobtrusive behavior in a remote habitat.

However, all species of Cetacea are listed by CITES as being on Appendix II unless listed on Appendix I. This places all Mesoplodon species on Appendix II.

US Federal List: no special status

CITES: appendix ii

IUCN Red List of Threatened Species: data deficient

Rounded Global Status Rank: G3 - Vulnerable

Reasons: Occurs in the cold temperate North Pacific Ocean; status is poorly known; not known to be killed in significant numbers incidental to fisheries.

Population

Population Trend

Major Threats

Comments: Significant threats (if any) are unknown. Has been caught in offshore gillnets, but not known to be killed in significant numbers incidental to fisheries.

Conservation Actions

No information has been found regarding any negative economic impact of this species on humans. It is unlikely that there is even much interaction between humans and this species, as M. carlhubbsi is typically found far from shore in deep waters.

Very small numbers of M. carlhubbsi are taken by commerical fisheries.

Positive Impacts: food

Data Deficient (DD)