Berardius arnuxii 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Cetartiodactyla Ziphiidae

Scientific Name: Berardius arnuxii Duvernoy, 1851
Common Name(s):
English Arnoux's Beaked Whale, Four-toothed Whale, Southern Four-toothed Whale, Southern Giant Bottlenosed Whale
French Bérardien D'Arnoux
Spanish Ballena De Pico De Arnoux, Ballenato De Arnoux
Taxonomic Notes: Some researchers have suggested that Baird’s and Arnoux’s Beaked Whales are members of the same species (see Kasuya 2002), but the lack of known morphological differences may simply be due to the small number of measured specimens (especially for Arnoux’s Beaked Whale). Analysis of mitochondrial and nuclear intron sequence data has however revealed multiple fixed genetic differences, confirming that these species are reproductively isolated and valid taxonomic entities (Dalebout 2002). The species name has frequently been misspelled arnouxi or arnuxi.

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 little information on abundance other than suggestions of natural rarity and no information on 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:Arnoux's beaked whales are found in a circumpolar pattern in the southern Hemisphere from the Antarctic continent and ice edges (ca. 78°S) north to about 34°S in the South Pacific (Kasuya 2002). They may even reach as far north as 24°N in the South Atlantic off South America. Nowhere within this range are they very well known or considered common. Most of the reported sightings are from the Tasman Sea and around the Albatross Cordillera in the South Pacific. The overwhelming majority of strandings have been from around New Zealand (Balcomb 1989, Jefferson et al. 1993). The northernmost records are strandings from Brazil, Argentina, South Africa, and Australia (Paterson and Parker 1994, Culik 2004).
Countries occurrence:
Antarctica; Argentina; Australia (South Australia, Tasmania); Brazil (São Paulo); Chile; Falkland Islands (Malvinas); French Southern Territories (Crozet Is., Kerguelen); Heard Island and McDonald Islands; New Zealand (Chatham Is.); South Africa (Eastern Cape Province, Western Cape); South Georgia and the South Sandwich Islands; Uruguay
FAO Marine Fishing Areas:
Atlantic – southwest; Atlantic – southeast; Atlantic – Antarctic; Indian Ocean – western; Indian Ocean – Antarctic; Indian Ocean – eastern; Pacific – southwest; Pacific – Antarctic; Pacific – southeast
Additional data:
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:There are no abundance estimates available for this species (Kasuya 2002), but in comparison with the sympatric southern bottlenose whale, Arnoux’s beaked whale is considered uncommon. In general, the species may be naturally rare. However, Arnoux's beaked whales seem to be relatively abundant in Cook Strait, at least during summer, and are also concentrated south of New Zealand and South America.

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:This species generally occurs in deep, cold temperate and subpolar waters, especially in areas with steep-bottomed slopes beyond the continental shelf edge (Kasuya 2002). However, some sightings have been associated with shallower regions, coastal waters, continental slopes or seamounts (Jefferson et al. 1993). Hobson and Martin (1996) observed groups of Arnoux’s beaked whales near the Antarctic Peninsula and found that their breath-holding capabilities make this species one of the most accomplished mammalian divers, capable of swimming up to an estimated 7 km between breathing sites in sea ice. The species seems well-adapted to life in ice-covered waters and may be able to exploit food resources inaccessible to other predators in the region (Ponganis et al. 1995).

Little is known of the feeding habits of Arnoux's beaked whales but they are assumed to be similar to those of their Northern Hemisphere relatives, Baird's beaked whales, consisting of benthic and pelagic fishes and cephalopods (Jefferson et al. 1993, Culik 2004). Squids are probably the main dietary items.

Threats [top]

Major Threat(s): Arnoux’s beaked whale has never been hunted to any significant degree, and direct anthropogenic threats are not known. However, a few whales have been taken for scientific study (see Jefferson et al. 1993). Considering that some beaked whale species are known to be vulnerable to large-mesh pelagic driftnets (e.g. Californian drift-netting for swordfish and sharks (Barlow and Cameron 2003)), it is highly likely that Arnoux’s beaked whales were caught in the large-scale drift-netting in the Tasman sea. Although current levels of bycatch are unknown, they are likely to be low due to adoption in 1989 of resolution 44/225 of the UN General Assembly, which called for effective conservation and management measures of living marine resources in areas of high seas drift-netting. Developing high-latitude fisheries, such as that for Antarctic toothfish, a significant proportion of which is illegal and unregulated, have the potential to reduce food available for large predators.

Arnoux's beaked whales have been reported trapped in sea ice, which may contribute to natural mortality. In recent years, there has been increasing concern that loud underwater sounds, such as active sonar and seismic operations, may be harmful to beaked whales (Malakoff 2002). The use of active sonar from military vessels has been implicated in mass strandings of a number of beaked whales including several Mesoplodon species and Indopacetus pacificus (Balcomb and Claridge 2001, Jepson et al. 2003, Cox et al. 2006, Wang and Yang 2006). Sound impacts may be important for all ziphiid species. However, this species’ range probably puts it largely outside the major areas of such impacts.

Predicted impacts of global climate change on the marine environment may affect this species of whale, given its cool-temperate to sub-Antarctic habitat, although the nature of impacts is unclear (Learmonth et al. 2006).

Conservation Actions [top]

Conservation Actions: The species is listed on Appendix I of CITES.

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. Berardius arnuxii. The IUCN Red List of Threatened Species 2008: e.T2762A9478212. . Downloaded on 24 September 2018.
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