Arch Beaked Whale

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

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

Other Physical Features: endothermic ; bilateral symmetry

Although M. carlhubbsi is not considered endangered or threatened by the U.S. governement, this species is still protected by U.S. laws and regulations.

Cetaceans fall under the responsibility of the National Marine Fisheries Services. This is a category under the Department of Congress.

According to the National Environmental Policy Act of 1969 (NEPA), there are major implications with regard to noise and its effects on marine mammals. Studies of noise effects have been done to provide the data needed for impact statements in regards to its effects on marine mammals. NEPA is the U.S. legislation under which Environmental Assessments and Impact Statements are required.

The U.S. Marine Mammal Protection Act of 1972 (MMPA) promotes the conservation of marine mammal populations and their habitats. They established a stand on the “taking of marine mammals.” “Taking” can be defined as including harassment as well as hunting, capturing, and killing. There are some exceptions to “taking”, however. It is allowed during scientific research as long as a scientific research permit is obtained. Also excused is the unintentional harassment of small numbers of marine mammals by human activities. An incidental take authorization must be obtained in this case.

In 1994, amendments were made to the MMPA. Harassment was defined as “any act of pursuit, torment, or annoyance which has the potential” to a) “injure a marine mammal or marine mammal stock in the wild,” or b) “disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns including, but not limited to, migration, breathing, nursing, breeding, deeding, or sheltering.”

Specifically, because of the limited scale of which Mesoplodon species are directly taken, and the “lack of effect that any kind of regulation would have on these kinds of subsistence fisheries,” there has been no known effort to regulate the take of these animals.

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 ; tactile ; acoustic ; chemical

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

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 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

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.

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 )

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 )

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

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); sexual ; 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)

Head Shape Melon is moderately bulbous and merges smoothly with rostrum, such that there is little demarcation between the forehead and long, narrow beak. The posterior half of the jaw is prominently arched in males; in females this arch is less pronounced, but still has a noticeable sinusoidal curve. Coloration In adult males, the rostrum and anterior portion of the mandible back to the posterior edge of the tooth are white. There is also a distinctive white patch of variable extent centered on the dorsal prominence of the melon. The rest of the body is relatively uniform dark grey to black, with no discernable differentiation between dorsal and ventral surfaces. Males often have extensive linear and ovate scars, especially on the flanks. The ventral surface of the body is lighter in females and juveniles, grading from medium gray dorsally to white on the midventral portions. The flipper pocket in females is darker than adjacent areas of thorax. Females and juveniles also have less contrast in the head coloration, but the rostrum and mandible are lighter than the rest of the head. Females appear to show greater variation in the pigmentation patterns around the rostrum. Both sexes exhibit fluke coloration that is lighter on the ventral surface than the dorsal surface. Flukes are also marked on ventral surface with concentric striations radiating anteriorly from the position of the caudal vertebra. Size Adult body length ranges between 4.8 to 5.3 m. Recorded maximum body length for both adult males and females is 5.3 m. Body length at birth is 2.5 m. Most Likely Confused With: Mesoplodon densirostris Mesoplodon ginkgodens Mesoplodon stejnegeri

Diagnostic features of the skull and mandible On the vertex of the dorsal skull the premaxillary bone extends forward of the nasal and frontal. Separates from Berardius and Ziphius. A sulcus (groove) running along the middle of the combined surfaces of the nasal bones so depresses their middle that it is the lateral portion of each nasal bone that reaches farthest forward on the vertex. Separates from Tasmacetus and Indopacetus. When the skull is upright and the long axis of the anterior half of the beak is horizontal, a horizontal plane transecting the summit of either maxillary prominence transects the mesethmoid bone. Separates from Hyperoodon. Tooth alveoli of mandible overlap the mandibular symphysis. Separates from Berardius, Ziphius, Tasmacetus, Indopacetus, Hyperoodon, M. grayi, M. europaeus, M. hectori, M. mirus, M. perrini, M. densirostris, M. ginkgodens, M. peruvianus, and M. stejnegeri. Basirostral groove absent or present as a shallow groove that does not extend past the prominental notch. Separates from M. layardii. The maxillary prominences rise 15 mm higher than the height of the premaxillaries where the latter passes between the former. Separates from M. bidens. In dorsal view, the right premaxilla extends slightly posterior beyond the right nasal. Separates from M. traversii. Antorbital tubercle formed by the maxilla and is underlain by the jugal bone. Separates from M. bowdoini.

Stranding Distribution M. carlhubbsi occurs in the temperate waters of the North Pacific, with a majority of stranding records occurring along the Pacific coast of North America. The northernmost record in eastern North Pacific occurs at Prince Rupert, British Colombia ~ 54o N; southernmost record is in San Diego, California, although the southern limit of the species may not be adequately known as there are limited records along the Pacific coast of Central America. In the western North Pacific the northernmost stranding record occurs at 38o N off the eastern coast of Japan near the confluence of the cold southerly flowing Oyashio current and the warm northerly flowing Kuroshio current.

Tooth position A single pair of teeth is positioned midway along the mouthline at the top of the jaw arch. Teeth are square at the root base and the teeth sit relatively upright in the jaw. Tooth exposure Erupted teeth in adult males are covered by gum tissue, with only the tip of tooth exposed. Teeth do not erupt in females or juveniles. Tooth shape The denticle is situated posterior to the anterior edge of the tooth forming a “shoulder” in the lateral profile of the tooth.

Adult males of this species are more readily identifiable than individuals of most other species of Mesoplodon. They have a white rostrum and white "cap" in front of the blowhole. Females and young are much more difficult to identify. Males also have a massive flattened tusk in the middle of each side of the lower jaw, which protrudes above the level of the upper jaw. Can be confused with: The white cap and beak tip, and large tusks may allow bulls of this species to be distinguished from other species of Mesoplodon.

Maximum known size is 5.3 m for both sexes. Weights of over 1 400 kg are attained. Newborns are about 2.5 m long.

Very little is known about the biology of this species. The long, white, parallel scratches on the bodies of males are thought to be caused by closed-mouth fighting in this and other species of Mesoplodon.Hubbs' beaked whales feed on squid and some deepwater fishes.

Some Hubbs' beaked whales have been taken by harpoon off Japan. IUCN: Insufficiently known.

Hubbs' beaked whale (Mesoplodon carlhubbsi) was initially thought to be an Andrews' beaked whale when discovered by ichthyologist Carl Hubbs; however, it was named in his honor when it was discovered to be a new species. This species has the typical dentition found in the genus, but its main outstanding features are a white "cap" on the head and very extensive scarring. The species is known from 31 strandings, a few at-sea sightings, and observations of two stranded whales that were kept in captivity for 16-25 days.

oceanic

Data Deficient (DD)