Mesoplodon mirus 

Scope: Global
Language: English

Translate page into:

Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Cetartiodactyla Ziphiidae

Scientific Name: Mesoplodon mirus True, 1913
Regional Assessments:
Common Name(s):
English True's Beaked Whale
French Mésoplodon De True, Mésoplodon De True
Spanish Ballena De Pico De True, Ballena De Pico De True, Zifio De True, Zifio De True
Taxonomic Notes: The peculiar disparate distribution pattern of this species suggests that there may actually be separate species or subspecies in the northern and southern hemispheres, but this has not been confirmed.

Assessment Information [top]

Red List Category & Criteria: Data Deficient ver 3.1
Year Published: 2008
Date Assessed: 2008-06-30
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)
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).
Previously published Red List assessments:

Geographic Range [top]

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).
Countries occurrence:
Australia; Bahamas; Bermuda; Brazil; Canada; France; Ireland; Madagascar; Morocco; Mozambique; Portugal (Azores, Portugal (mainland)); South Africa; Spain (Canary Is., Spain (mainland)); United Kingdom; United States
FAO Marine Fishing Areas:
Atlantic – western central; Atlantic – northeast; Atlantic – northwest; Atlantic – southeast; Indian Ocean – eastern
Additional data:
Range Map:Click here to open the map viewer and explore range.

Population [top]

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.
Current Population Trend:Unknown
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

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).

Threats [top]

Major Threat(s): 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).

Conservation Actions [top]

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.

Citation: 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. The IUCN Red List of Threatened Species 2008: e.T13250A3430702. . Downloaded on 20 September 2018.
Disclaimer: To make use of this information, please check the <Terms of Use>.
Feedback: If you see any errors or have any questions or suggestions on what is shown on this page, please provide us with feedback so that we can correct or extend the information provided