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Overview

Brief Summary

True's beaked whale (Mesoplodon mirus) is one of 21 species of beaked whales (Hyperoodontidae or Ziphiidae), medium-sized whales with distinctive, long narrow beaks and dorsal fins which are set far toward the posterior. This species is a marine mammal within the order of cetaceans.

True's beaked whale is a toothed whale and can be recognised as such by the single blowhole as well as the presence of teeth (rather than baleen). Because of the highly disjunctive distribution patches of True's beaked whale, it is possible that the northern and southern hemisphere temperate ocean populations are actually distinct species or subspecies. Threats to the species include bycatch and underwater noise pollution.
  • * Encyclopedia of Earth. True's beaked whale. Lead author: Encyclopedia of Life. Topic ed. C.Michael Hogan. Ed.-in-Chief Cutler J.Cleveland
  • * 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 mirus. In: IUCN 2010. IUCN Red List of Threatened Species
  • * Cox, T. M., Ragen, T. J., Read, A. J., Vos, E., Baird, R. W., Balcomb, K., Barlow, J., Caldwell, J., Cranford, T., Crum, L., D'Amico, A., D'Spain, A., Fernández, J., Finneran, J., Gentry, R., Gerth, W., Gulland, F., Hildebrand, J., Houser, D., Hullar, T., Jepson, P. D., Ketten, D., Macleod, C. D., Miller, P., Moore, S., Mountain, D., Palka, D., Ponganis, P., Rommel, S., Rowles, T., Taylor, B., Tyack, P., Wartzok, D., Gisiner, R., Mead, J. and Benner, L. 2006. Understanding the impacts of anthropogenic sound on beaked whales. Journal of Cetacean Research and Management 7(3): 177-187.
  • * Gomercic, H., Gomercic, M. D., Gomericic, T., Lucic, H., Dalebout, M., Galov, A., Skrtic, D., Curkovic, S., Vukovic, S. and Huber, D. 2006. Biological aspects of Cuvier's beaked whale (Ziphius cavirostris) recorded in the Croatian part of the Adriatic Sea. European Journal of Wildlife Research 52(3): 182-187.
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Description

Found along the North American coastline from Nova Scotia to the Bahamas, True’s beaked whale also inhabits temperate waters off the coast of Europe, and there are records of the species from near Australia and South Africa. Squid beaks have been found in the stomachs of stranded animals, but no fish. Very few have been weighed or measured. The longest male on record measured 5.3 m; the longest female, which weighed 1,394 kg, was 5.1 m long.

Links:
Mammal Species of the World
  • Original description: True, F.W., 1913.  Smithsonian Miscellaneous Collections, 60(25):1.
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Brief description of True's Beaked Whale

Did You Know?

• True's beaked whales receive their common name from Frederick W. True, who was a curator at the Smithsonian Institution, and described the species from an animal that stranded on a beach in North Carolina (Reeves et al. 2002).

• Animals living in the northern hemisphere have different coloration from those living in the southern hemisphere.

Status

MMPA - True's beaked whales, like all marine mammals, are protected under the MMPA.

CITES Appendix II - throughout its range

Taxonomy

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Cetacea

Family: Ziphiidae

Genus: Mesoplodon

Species: mirus

Species Description

True's beaked whales are little known members of thebeaked whale family (Ziphiidae). As adults, True's beaked whales can reach lengths of 15.5-17.5 ft (4.8-5.4 m) and weigh at least 2,200-3,000 lbs (1,020-1,400 kg). Females may be slightly larger than males. Adult males can be distinguished from females and juveniles by a pair of teeth visible on the tip of the lower jaw. The mouthline is typically straight or slightly curved.

True's beaked whales have a relatively small to medium-sized body with a moderately short beak, as well as a rounded sloping melon. They have a small, wide-based, slightly "falcate" "dorsal" fin located far down (about two-thirds) the animal's back. Their coloration varies from gray to brown on the dorsal side with a paler ventral side. The coloration in the southern hemisphere is different from animals in the northern hemisphere. Individuals in the southern hemisphere have more white coloration on their back, tailstock and underside. Mature males may have more linear scarring covering the body than other animals. The linear scars are probably the result of males battling for access to females during mating. This species of beaked whale is difficult to observe and identify at sea due to a low profile at the surface and a small, inconspicuous blow. Few have been seen alive at sea.

Many species of beaked whales (especially those in the genus Mesoplodon) are very difficult to distinguish from one another (even when dead). At sea, they are challenging to observe and identify to the species level due to their cryptic, skittish behavior, a low profile, and a small, inconspicuous blow at the waters surface; therefore, much of the available characterization for beaked whales is to genus level only. Uncertainty regarding species identification of beaked whales often exists because of a lack of easily discernable or distinct physical characteristics.

When observed, True's beaked whales are usually alone or in small, closely associated groups averaging 2-6 animals. While diving, they use suction to feed on small fish and cephalopods (e.g., squid) in deep waters. This species has been known to breach and occasionally display surface active behaviors.

Very little is known about reproduction in True's beaked whales. Females generally give birth to a single newborn calf that is about 6.5-8 ft (2.0-2.5 m) long and weighs about 300 lbs (136 kg). The estimated lifespan of this species is unknown.

Habitat

True's beaked whales prefer deep warm temperate waters of the North Atlantic Ocean as well as at least two other areas in the Southern Hemisphere (e.g., Indian Ocean).



Distribution

True's beaked whales occur throughout the northern and southern hemispheres. Their range includes areas off of Nova Scotia (Canada), Ireland, Europe, the Canary Islands, Bermuda, Florida, and the Bahamas in the Atlantic, as well as off the coasts of Brazil, Madagascar, South Africa, and southern Australia. There are no known seasonal movements or migrations for this species.

Population Trends

For management purposes, True's beaked whales inhabiting U.S. waters have been placed in the Western North Atlantic stock. No current population estimates are available for this species of beaked whale. There are insufficient data to determine the population trends for this species. The status of this stock is unknown, but is considered "strategic."

Threats

May be sensitive to underwater sounds and anthropogenic noise. Anthropogenic noise levels in the world's oceans are an increasing habitat concern, particularly for deep-diving cetaceans like True's beaked whales that use sound to feed, communicate, and navigate in the ocean.

Previously, incidentally taken (by catch) in fisheries using driftnets and gillnets off the U.S. Atlantic coast, but no recent reports exist

Conservation Efforts

The International Union for Conservation of Nature and Natural Resources (IUCN's) Red List of Threatened Species considers this species "Data Deficient" due to insufficient information on population status and trends.

Regulatory Overview

This species is protected under the Marine Mammal Protection Act of 1972, as amended.

References:

Reeves, R. R., P. A. Folkens, et al. (2002). Guide to Marine Mammals of the World. New York, Alfred A. Knopf. p.276-277.

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Comprehensive Description

Description

 Mesoplodon mirus is a toothed whale and can be recognised as such by the single blowhole and the presence of teeth (rather than baleen). It is a member of the beaked whale family with the characteristic V-shaped crease on the throat and the short dorsal fin set relatively far back. True's beaked whale is a small beaked whale that can reach up to 5.3 m in length. The lower jaw has a single pair of teeth (exposed only in adult males). The smooth forehead rises at a shallow angle and is bulging in appearance. It has a distinct beak and the mouthline is curved down at rear. True's beaked whale has a grey dorsal and lateral colouration with a lighter belly and darker areas around the eyes. Adults are often covered with scratches and scars.True's beaked whale may be confused with Sowerby's beaked whale Mesoplodon bidens but can be recognised by its bulging but smooth forehead and its slightly shorter beak. Little is known about the aggregational behaviour of True's beaked whales but it is not expected to differ from similar species such as Mesoplodon bidens (Kinze, 2002).
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Distribution

Temperate waters of both sides of the North Atlantic, and temperate waters of the Southern Hemisphere (known from South Africa and Australia).
  • North-West Atlantic Ocean species (NWARMS)
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scattered in all oceans
  • UNESCO-IOC Register of Marine Organisms
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Range Description

True's beaked whales appear to have a disjunct, anti-tropical distribution (Mead 1989, MacLeod et al. 2006). In the Northern Hemisphere, they are known only in the North Atlantic, from records in eastern North America (Nova Scotia to Florida), Bermuda, Europe to the Canary Islands, the Bay of Biscay, and the Azores. They also occur at least in the southern Indian Ocean, from South Africa, Madagascar, southern Australia and the Atlantic coast of Brazil (MacLeod et al. 2006). The species does not generally occur within 30° north or south of the equator, which may indicate that the northern and the southern subpopulations are isolated from one another. This is supported by morphological and coloration differences (Ross 1969, Ross 1984).
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occurs (regularly, as a native taxon) in multiple nations

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National Distribution

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Global Range: Known from offshore temperate waters of North Atlantic (strandings from Nova Scotia to Florida, and in the British Isles, France, and Canary Islands), south Atlantic coast of South Africa, and Australia and New Zealand (IUCN 1991; Mead and Brownell, in Wilson and Reeder 1993).

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Stranding distribution

Stranding Distribution

Inhabits the temperate waters of the North Atlantic. Although there is considerable overlap, it appears to prefer slightly colder waters than M. europaeus. Most stranding records are from the western North Atlantic, with the relatively few strandings in the eastern North Atlantic focused around Ireland and France. The northernmost record is from Saint Ann's Bay, Nova Scotia and southernmost from San Salvador Island, Bahamas. It has been reported in the Gulf of Mexico, but further verification of its occurence in this area is needed.

From strandings in South Africa and South Australia it is evident that this species is also distributed in the warm temperate waters of the southern Indian Ocean. There appears to be a distributional break in the tropical Atlantic Ocean.

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Physical Description

Morphology

Tooth morphology

Tooth position

A single pair of anteriorly inclined teeth are positioned at apex of the mandible.

Tooth exposure

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

Tooth shape

Teeth are oval in cross section and much less transversely flattened than other Mesoplodon species.

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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 bones. Separates from Berardius and Ziphius.

A sulcus (groove) running along the middle of the combined surfaces of the nasal bones so depresses their combined 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 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. layardii, M. peruvianus, M. stejnegeri, and M. traversii.

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

Lacrimal and frontal comprise bones of antorbital tubercle apex. Separates from M. hectori.

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External morphology

Head Shape

Melon is well rounded and slopes fairly steeply onto a relatively short beak. There is a distinct indentation behind the blowhole. The mouthline is weakly sinusoidal.

Coloration

The pigmentation pattern of northern hemisphere specimens of both sexes of M. mirus consists of a medium gray dorsal body color with a light gray ventral surface. There is a dark area 5-10 cm in diameter around the eye. An area of white pigmentation 10-15 cm in diameter that extends from the anus to the midpoint of the genital slit.

In the southern hemisphere, specimens have a white area extending from the anterior insertion of the dorsal fin back to the anterior edge of the flukes. This patch runs posteroventrally to connect with its counterpart on the other side.

Size

Adult body length ranges between 4.5 to 5.2 m. Recorded maximum body length for adult males and females is 5.3 m and 5.1 m, respectively. Length at birth is 2.3 m.

Most Likely Confused With:

Mesoplodon bidens

Mesoplodon europaeus

Mesoplodon hectori

Ziphius cavirostris

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Size

Length: 5200 cm

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Size in North America

Length:
Range: up to 5.5 m males; up to 5.1 m females

Weight:
Range: 1,394 kg female
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Type Information

Type for Mesoplodon mirus True, 1913
Catalog Number: USNM 175019
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Mammals
Sex/Stage: Female;
Preparation: Skull; Partial Skeleton; Cast
Collector(s): Collector Unknown
Year Collected: 1912
Locality: Beaufort, Harbor (Bird Island Shoal), Carteret, North Carolina, United States, North America, North Atlantic Ocean
  • Type: True, F. W. March 14, 1913. Smith. Misc. Coll. 60 (25): 1.
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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
M. mirus is probably a deep water pelagic species, like other ziphiids (Houston 1990).

Like other members of the genus, stranded animals have had squid (mostly Loligo spp.) in their stomachs. They may also take fish, at least occasionally. Stable isotope analysis has found that this species feeds at a similar trophic level to other Mesoplodon species with which it is sympatric, but at lower trophic level than Cuvier’s beaked whale and the northern bottlenose whales which suggests that it feeds on smaller prey than these latter species (MacLeod 2005).

Systems
  • Marine
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Depth range based on 2 specimens in 1 taxon.
Water temperature and chemistry ranges based on 2 samples.

Environmental ranges
  Depth range (m): 0 - 0
  Temperature range (°C): 14.394 - 17.743
  Nitrate (umol/L): 1.003 - 2.317
  Salinity (PPS): 32.419 - 33.836
  Oxygen (ml/l): 5.571 - 6.061
  Phosphate (umol/l): 0.336 - 0.370
  Silicate (umol/l): 2.105 - 2.466

Graphical representation

Temperature range (°C): 14.394 - 17.743

Nitrate (umol/L): 1.003 - 2.317

Salinity (PPS): 32.419 - 33.836

Oxygen (ml/l): 5.571 - 6.061

Phosphate (umol/l): 0.336 - 0.370

Silicate (umol/l): 2.105 - 2.466
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Habitat Type: Marine

Comments: Inhabits deep, cold waters.

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 True's beaked whale is an oceanic species that may be seen at the surface but little is known on what depth they may dive to.
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Migration

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.

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Trophic Strategy

Comments: Evidently the diet consists primarily of squid.

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Life History and Behavior

Cyclicity

Comments: Active day and night.

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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 not believed to be uncommon but 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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National NatureServe Conservation Status

United States

Rounded National Status Rank: NNR - Unranked

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NatureServe Conservation Status

Rounded Global Status Rank: G3 - Vulnerable

Reasons: Known from offshore temperate waters of North Atlantic; conservation status is poorly known.

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Population

Population
Until recent years, True’s beaked whales have been only rarely identified at sea, and there are no estimates of abundance. However, the species is not thought to be rare in the North Atlantic.

There is no information on trends in the global abundance of this species.

Population Trend
Unknown
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Threats

Major Threats
Almost no information is available on the threats and status of this species. It appears never to have been hunted. Entanglement in fishing gear, especially gillnets in deep water (e.g., for billfish and tuna), is probably the most significant threat.

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, the strap-toothed 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 Mesoplodon mirus indicates that they have swallowed discarded plastic items. This may eventually lead to death (e.g. Scott et al. 2001).
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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

True's beaked whale

True's beaked whale!<-- This template has to be "warmed up" before it can be used, for some reason -->

The True's Beaked Whale (Mesoplodon mirus) is a medium sized whale in the Mesoplodont genus. The common name is in reference to Frederick W. True, a curator at the United States National Museum (now the Smithsonian). There are two distinct populations in the Atlantic and Indian ocean (this species is absent in the tropics) which may be separate subspecies.

Contents

Physical description

Skeleton of a True's beaked whale.

This whale has a normal Mesoplodont body, except that it is rotund in the middle and tapering towards the ends. The two distinctive teeth on the males are small and set on the very end of the beak. The melon is rather bulbous, and leads into a short beak. There is a crease behind the blowhole, and a sharp dorsal ridge on the back near the dorsal fin. The coloration is gray to brownish gray on the back which is lighter below, and notably darker on the "lips", around the eye, and near the dorsal fin. There is sometimes a dark blaze between the head and dorsal fin as well. One female in the Southern Hemisphere was bluish black with a white area between the dorsal fin and tail as well as a light gray jaw and throat, as well as black speckling. Scars from fighting and cookiecutter sharks are present on males. This species reaches around 5.3 metres (17 ft) with the females weighing 1,400 kilograms (3,100 lb) and the males weighing 1,010 kilograms (2,200 lb). They are around 2.2 metres (7.2 ft) long when born.

Behavior

They have been seen in small groups, and are believed to be squid eaters. It is believed that when a whale is injured, another whale stays with it to nurse it. Other than that, little else is known.

Population and distribution

One population, possibly genetically distinct, lives in the Northern Hemisphere and has stranded from Nova Scotia in the western Atlantic to Ireland in the eastern Atlantic and as far south as Florida, the Bahamas, and Canary Islands. Another population lives in the Southern Hemisphere and has stranded in South Africa and Australia. The species does not inhabit the Southern Atlantic or Northern Indian Ocean, and appears to avoid tropical waters. No population estimates have been established, but it is believed to be one of the rarest species of whale.

Conservation

This species has not been hunted and has not been a victim of fishing nets.

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 mirus. 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

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Names and Taxonomy

Taxonomy

Comments: Slight differences in pigmentation and cranial morphology indicate that populations in the Northern and Southern hemispheres comprise distinct breeding populations (1989 Rep. Int. Whaling Comm. 39:117-129).

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