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Overview

Brief Summary

Description

Hector’s beaked whale is known from the South Atlantic, the South Pacific, and the Indian Ocean off South Africa, which made cetologists (scientists who study whales) think it was a Southern Hemisphere species, but since 1981, several strandings in California have indicated that the species also lives in the Northern Hemisphere. Information about the animal is very limited.

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Mammal Species of the World
  • Original description: Gray, J.E., 1871.  Annals and Magazine of Natural History, ser. 4, 8:116.
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Distribution

circum-global
  • UNESCO-IOC Register of Marine Organisms
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Range Description

Hector's beaked whale is considered to be a Southern Hemisphere cool temperate species (Mead 1989). The records (mostly strandings) are from southern South America, South Africa, southern Australia, and New Zealand. The single confirmed sighting record is from southwestern Australia (Gales et al. 2002). It has been speculated that the species has a continuous distribution in the Atlantic and Indian oceans at least from South America to New Zealand. Although there are no current records from the central and eastern Pacific Ocean, the range may prove to be circumpolar. These animals may be relatively common around New Zealand.

Previously, it was supposed that this species may also be vagrant in southern California, where there were several strandings and a possible sighting from 1975 to 1979 (Mead 1981, Mead and Baker 1987, Rice 1998). However, the California specimens were recently recognised as a new species Mesoplodon perrini, which is found in the eastern North Pacific (Dalebout et al. 1998; Dalebout et al. 2002).
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Standing distribution

Stranding Distribution

Occurs in the South Pacific, South Atlantic and Indian oceans below 40oS. It apparently frequents more southernly (colder) waters.

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Physical Description

Morphology

Tooth morphology

Tooth position

A single pair of large teeth are positioned at apex of the mandible. Teeth incline anteriorly.

Tooth exposure

Nearly all of erupted teeth in adult males are exposed above the gumline. Teeth do not erupt in female or juveniles.

Tooth shape

The lateral profile of the exposed tooth is shaped like an isosceles triangle. Instead of being smoothly convex the anterior margin has three flattish areas between the denticle and root. The anterior margin is also shorter than the posterior margin. The denticle is on the dorso-anterior edge of the tooth. The angle formed by the denticle is between 85 to 90 degrees.

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Skull morphology

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.

ooth alveoli of mandible are positioned at the apex of the mandible.Separates from M. bidens, M. bowdoini, M. carlhubbsi, M. densirostris, M. europaeus, M. grayi, M. ginkgodens, M. layardi, M. peruvianus, M. stejnegeri, and M. traversi.

The space between the nasals is wide with parallel sides and "U" shaped. Separates from M. perrini.

Maxilla and lacrimal comprise bones of antorbital tubercle. Separates from M. mirus.

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External Morphology

Head Shape

Forehead slopes steeply over a slightly bulging melon. The beak is short with a relatively straight mouthline.

Coloration

Descriptions of coloration in M. hectori are lacking. The main accounts in the literature are based on specimens of that have subsequently been attributed to a separate species, M. perrini. Previous accounts describe an animal that is dark dorsally and pale ventrally.

Size

Adult body length ranges between 4 to 5 m. Recorded maximum body length for adult males and females is 5 m and 4.3 m, respectively. Length at birth is 2 m.

Most Likely Confused With:

Mesoplodon mirus

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Size

Size in North America

Length:
Range: up to 4.3 m males; up to 4.4 m females

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Ecology

Habitat

cool temperate, oceanic
  • UNESCO-IOC Register of Marine Organisms
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Habitat and Ecology

Habitat and Ecology
In the only known confirmed identification of this species alive at sea, a single individual was observed in shallow waters, nearshore in Western Australia – almost definitely atypical for the species (Gales et al. 2002). Hector's beaked whale presumably occurs in deep waters beyond the edge of the continental shelf, as do other members of the genus.

Little is known of the diet, but Hector's beaked whales are known to feed on squid, like most other beaked whales.

Systems
  • Marine
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
DD
Data Deficient

Red List Criteria

Version
3.1

Year Assessed
2008

Assessor/s
Taylor, B.L., Baird, R., Barlow, J., Dawson, S.M., Ford, J., Mead, J.G., Notarbartolo di Sciara, G., Wade, P. & Pitman, R.L.

Reviewer/s
Hammond, P.S. & Perrin, W.F. (Cetacean Red List Authority)

Contributor/s

Justification
There is no information on global abundance or trends in abundance for this species. It is potentially vulnerable to low-level threats and a 30% global reduction over three generations cannot be ruled out (criterion A).

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

Population
There is no information on populations of this species.

Population Trend
Unknown
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Threats

Major Threats
Direct hunting has never been associated with this species. Pervasive gillnet and longline fisheries throughout the species' range raises concern that some bycatch is likely. Even low levels of bycatch might have an impact on this species.

This species, like other beaked whales, is likely to be vulnerable to loud anthropogenic sounds, such as those generated by navy sonar and seismic exploration (Cox et al. 2006).

As a temperate water species, Hector’s beaked whale may be vulnerable to the effects of climate change as ocean warming may result in a shift or contraction of the species range as it tracks the occurrence of its preferred water temperatures (Learmonth et al. 2006). The effect of such changes in range size or position on this species is unknown.

Evidence from stranded individuals of several similar species indicates that they have swallowed discarded plastic items, which may eventually lead to death (e.g. Scott et al. 2001); this species may also be at risk.
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Management

Conservation Actions

Conservation Actions
The species is listed in Appendix II of CITES. Research is needed to determine the impacts of potential threatening processes on this species.
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Relevance to Humans and Ecosystems

Risks

IUCN Red List Category

Data Deficient (DD)
  • IUCN (2008) Cetacean update of the 2008 IUCN Red List of Threatened Species.
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Wikipedia

Hector's beaked whale

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Hector's Beaked Whale, Mesoplodon hectori, is a small Mesoplodont living in the Southern Hemisphere. This whale is named after Sir James Hector, a founder of the colonial museum in Wellington, New Zealand. Some specimens that have washed up and been sighted in California that were once thought to belong to this species have subsequently been shown through analysis of mtDNA and detailed morhological examination to be a new species, Perrin's Beaked Whale (Dalebout et al. 2002). As of 2007, they have yet to be seen alive in the wild.

Note that some data supposedly referring to this species, especially juveniles and males, turned out to be based on the misidentified specimens of Perrin's Beaked Whale - especially since the adult male of Hector's Beaked Whale was only more recently described. See Perrin's Beaked Whale for specimen data. Dalebout et al. (2002) specifically list Mead (1981), Mead (1984), Mead & Baker (1987), Mead (1989), Baker (1990), Jefferson et al. (1993), Mead (1993), Carwardine (1995), Reeves & Leatherwood (1994), Henshaw et al. (1997) and Messenger & McQuire (1998) as erroneously attributing data from the new species to Hector's Beaked Whale.

Contents

Physical description

Reaching a maximum length of about 4.2 meters (1.9 m when born), and with an estimated weight of about 1 tonne (1.032 tons), Hector's is one the smallest of the beaked whales. It is known from only a few stranded animals. Hector's Beaked Whales are dark greyish-brown dorsally, paler ventrally and may have white or pale lower jaws. The melon, which is not very prominent, slopes quite steeply to the short beak. Adult males have a pair of flattened, triangular teeth near the tip of the lower jaw. As with most other beaked whales, the teeth do not erupt in females. The dorsal fin is triangular to slightly hooked, small, and rounded at the tip. The leading edge of the dorsal fin joins the body at a sharp angle.

Diet

Nothing is known about the diet of this species, although it is assumed to feed on deepwater squid and fish. Because they lack functional teeth, they presumably capture most of their prey by suction.

Behavior

With only two probable sightings, there is little information on the behavior of this whale. This species may be unusual for a Mesoplodon because, in both sightings, one of the animals seemed inquisitive and actually approached the boat. Body scarring suggests there may be extensive fighting between males, which is common in beaked whales.

Breeding

Nothing is known about breeding in this species. Sightings are rare due to their deep-ocean distribution, elusive behaviour and possible low numbers.

Population and Distribution

Hector's Beaked Whale has a circumpolar distribution in cool temperate Southern Hemisphere waters between approximately 35° and 55°S. Most records are from New Zealand, but there are also reports from Falkland Sound, Falkland Islands, Lottering River, South Africa, Adventure Bay, Tasmania, and Tierra del Fuego, in southern South America.

Conservation

This species has never been hunted at all, and has not entangled itself in fishing gear. Most sightings of the whale have been stranded specimens on beaches, particularly in New Zealand.

Specimens

  1. MNZ MM001834 - 16 July 1980; Kaikoura, New Zealand


References

  1. ^ Taylor, B.L., Baird, R., Barlow, J., Dawson, S.M., Ford, J., Mead, J.G., Notarbartolo di Sciara, G., Wade, P. & Pitman, R.L. (2008). Mesoplodon hectori. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 24 March 2009. Database entry includes a brief justification of why this species is of data deficient.

Bibliography

  • Baker, Alan N. (1990): Whales and dolphins of New Zealand and Australia: An identification guide. Victoria University Press, Wellington.
  • Carwadine, M. (1995): Whales, dolphins and porpoises. HarperCollins, London.
  • Dalebout, Merel L.; Mead, James G.; Baker, C. Scott; Baker, Alan N. & van Helden, Anton L. (2002): A New Species of Beaked Whale, Mesoplodon perrini sp. n. (Cetacea: Ziphiidae), Discovered Through Phylogenic Analysis of Mitochondrial DNA Sequences. Marine Mammal Science 18(3): 577-608. doi:10.1111/j.1748-7692.2002.tb01061.x PDF fulltext
  • Henshaw, M.D.; Leduc, R.G.; Chivers, S.J. & Dizon, A.E. (1997): Identification of beaked whales (family Ziphiidae) using mtDNA sequences. Marine Mammal Science 13(3): 487-495. doi:10.1111/j.1748-7692.1997.tb00656.x (HTML abstract)
  • Jefferson, T.A.; Leatherwood, S. & Webber, M.A. (1993): FAO species identification guide: Marine mammals of the world. United States Environment Programme & Food and Agriculture Organization of the United Nations (FAO), Rome. PDF fulltexr
  • Mead, James G. (1981): First records of Mesoplodon hectori (Ziphiidae) from the northern hemisphere and a description of the adult male. Journal of Mammalogy 62(2): 430-432. doi:10.2307/1380733 (First page image)
  • Mead, James G. (1984): Survey of reproductive data for the beaked whales (Ziphiidae). Report of the International Whaling Commission Special Issue 6: 91-96.
  • Mead, James G. (1989): Beaked whales of the genus Mesoplodon. In: Ridgway, S.H. & Harrison, R. (eds.): Handbook of marine mammals Vol.4: 349-430. Academic Press, London.
  • Mead, James G. (1993): The systematic importance of stomach anatomy in beaked whales. IBI Reports 4: 75-86.
  • Mead, James G. & Baker, Alan N. (1987): Notes on the rare beaked whale, Mesoplodon hectori (Gray). Journal of the Royal Society of New Zealand 17: 303-312.
  • Messenger, S.L. & McQuire, J.A. (1998): Morphology, molecules and the phylogenetics of cetaceans. Systematic Biology 47(1): 90-124. doi:10.1080/106351598261058 (HTML abstract)
  • Perrin, William F.; Wursig, Bernd & Thewissen, J.G.M (eds.) (2002): Encyclopedia of Marine Mammals. Academic Press. ISBN 0-12-551340-2
  • Reeves, Randall R. & Leatherwood, S. (1994): Dolphins, porpoises and whales: 1994-98 Action plan for the conservation of cetaceans. IUCN, Gland, Switzerland. ISBN 2-8317-0189-9
  • Reeves, Randall R.; Steward, Brent S.; Clapham, Phillip J. & Owell, James A. (2002): Sea Mammals of the World. A & C Black, London. ISBN 0-7136-6334-0
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