Overview

Brief Summary

ARNOUX'S BEAKED WHALE Berardius arnuxii

The second largest beaked whale, Arnoux’s is probably the most southernmost ranging of the family. The northern limit of its range is at about 34°S and from there it ranges to the edge of the Antarctic pack ice and beyond – it is regularly found in open leads in the pack ice 50km or more from the open sea. Although rarely observed in the open ocean the occurrence of individuals in confined space of ice leads has allowed some opportunistic studies of their behaviour. This appears to be a fairly sociable species (like its northern hemisphere counterpart Baird’s beaked whale) – with no aggression being recorded between individuals even in confined surroundings. A typical dive appears to be about 40 minutes, and may be up to 70 minutes in duration. On average they surface for between 1.2 and 6.8 minutes and breath at a rate of 9.6 breaths per minute – about once every 6 seconds. Of 30 animals closely examined in ice leads 11 were toothless, 16 had one pair of teeth and 3 had two pairs (always in the lower jaw) but how this related to the age and sex of the animals involved isn’t known. Given its range this species appears able to exploit a feeding niche under the pack ice. 

  • The above website cites this publication as a "Key Reference." Hobson R.P & Martin A.R. (1996) Behaviour and dive times of Arnoux’s beaked whales, Berardius arnuxii, at narrow leads in fast ice. Canadian Journal of Zoology. 74 pp388-393
  • http://www.beakedwhaleresource.com/bwarnouxs.htm
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Biology

As a result of the apparent rarity and open-ocean habitat of Arnoux's beaked whale, little is currently known about its biology (1) (5). Like other beaked whales, this species is an accomplished diver and, like Baird's whale, probably forages on the sea-bed at depths of between 1,000 and 3,000 metres (4). The exceptional diving abilities of Arnoux's beaked whale also allow it to enter regions covered by sea ice, where it may travel up to seven kilometres between breathing sites, locating them with uncanny accuracy (1) (5). Such behaviour may offer the benefit of access to this species' preferred diet of bottom-dwelling and pelagic fish and squid without competition from other predators (1) (5). Although this species is generally encountered in groups of six to ten individuals, reports of congregations of as many as 80 have also been recorded (4)
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Description

One of the largest beaked whale species, Arnoux's beaked whale is almost identical in appearance to its close relative, Baird's beaked whale (Berardius bairdii), but is smaller in size (2). The body is uniform blackish-brown or dark grey, with irregular white blotches on the underparts of some individuals (2), and may be extensively scarred with single or paired rake marks made by the teeth of conspecifics (2) (4). The melon is relatively small, with a steep, almost vertical forehead, beneath which a short, tapering snout projects (2) (5). Interestingly, the lower jaw projects well beyond the upper jaw, so that the lower, front pair of large teeth is constantly exposed (2).
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Distribution

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).
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Range

Arnoux's beaked whale is found in the southern Hemisphere, in a circumpolar distribution, from Antarctica as far North as southern Brazil and South Africa (1). Populations appear to be most concentrated to the south of New Zealand and South America (2)
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Ecology

Habitat

cold temperate and subpolar
  • UNESCO-IOC Register of Marine Organisms
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Habitat and Ecology

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.

Systems
  • Marine
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Depth range based on 6 specimens in 1 taxon.
Water temperature and chemistry ranges based on 6 samples.

Environmental ranges
  Depth range (m): 0 - 0
  Temperature range (°C): -1.427 - 0.303
  Nitrate (umol/L): 23.620 - 28.422
  Salinity (PPS): 33.662 - 33.932
  Oxygen (ml/l): 7.931 - 8.204
  Phosphate (umol/l): 1.459 - 1.807
  Silicate (umol/l): 25.926 - 52.096

Graphical representation

Temperature range (°C): -1.427 - 0.303

Nitrate (umol/L): 23.620 - 28.422

Salinity (PPS): 33.662 - 33.932

Oxygen (ml/l): 7.931 - 8.204

Phosphate (umol/l): 1.459 - 1.807

Silicate (umol/l): 25.926 - 52.096
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Arnoux's beaked whale is usually found well-offshore, in deep, cold, temperate or sub-polar waters beyond the edge of the continental shelf (1) (2). Occasional sightings have also been made of this species in shallower coastal waters, and around seamounts and the continental slope (1). This species appears to be particularly well-adapted to living in ice-covered waters, and is frequently found around the Antarctic ice-edge and under pack-ice in the summer, but normally moves away from the ice-edge in winter (5).
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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 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).

History
  • 1994
    Insufficiently Known
    (Groombridge 1994)
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Status

Classified as Data Deficient (DD) on the IUCN Red List and listed on Appendix I of CITES (3).
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Population

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.

Population Trend
Unknown
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Threats

Major Threats
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).
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A general lack of data about Arnoux's beaked whale means that its global population and conservation status are unclear. It is, however, generally thought to be rare and therefore may be adversely affected by some of the threats that are known to be causing declines in other beaked whale species. While this species is not generally targeted directly by commercial fisheries, it may be caught incidentally during drift-netting. In addition, commercial fishing in Antarctic waters may reduce food supplies for this species, particularly as a significant proportion of these fisheries are illegal and unregulated. Other issues may include climate change, as well as the use of active sonar by military vessels, which has been implicated in mass strandings of some beaked whale species (1).
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Management

Conservation Actions

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

Although it does not appear to be particularly threatened by hunting, Arnoux's beaked whale is listed on Appendix I of the Convention on International Trade in Endangered Species (CITES), which means that all international trade in this species in prohibited (3). In addition, this species is likely to benefit from the 1989 UN General Assembly resolution 44/225, which calls for effective conservation and management measures of living marine resources in areas of high seas drift-netting (1).
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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

Giant beaked whale

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

The genus Berardius contains two species of beaked whale, Baird's beaked whale and Arnoux's beaked whale. The two species are so similar that some scientists regard their separation into distinct species as a historical anomaly.[2] The two species are the largest of all beaked whales and collectively they are sometimes referred to as the giant beaked whales.

Baird's beaked whale was first described by Leonhard Hess Stejneger in 1883 from a specimen found in the Bering Sea. The species is named for Spencer Fullerton Baird, a past Secretary of the Smithsonian Institution. Arnoux's beaked whale was described in 1851 by Duvernoy from a skull found in New Zealand. Berard was the captain of the ship that carried the skull from New Zealand to France where Duvernoy analysed it. Arnoux was the doctor on board the ship.[3]

Contents

Physical description

The two species have very similar features and would be indistinguishable at sea if they did not exist in disjoint locations. Arnoux's is generally shorter. Estimated lengths of live Arnoux's at sea have been up to 12m but all dead specimens have been considerably smaller. The Baird's on the other hand have been confirmed to grow to 12-13m. The weight is up to 14,000 kg.

Both whales have a very long prominent beak, even by beaked whale standards. The lower jaw is longer than the upper and the front teeth are visible even when the mouth is fully closed. The melon is particularly bulbous. The body shape is slender - the girth is only 50% of length. The body is uniformly coloured and a particular individual's colour may be anything from light grey through to black. The flippers are small, rounded and set towards the front of the body. The dorsal fin similarly is small and rounded and set about three-quarters of the way along the back. Both species pick up numerous white scars all over the body as they age and may be a rough indicator of age. There is little sexual dimorphism in either species.

Population and distribution

The two species ranges do not overlap. This is perhaps the most significant reason why they have historically been treated as separate species.

Arnoux's inhabit great tracts of the Southern Ocean. Beachings in New Zealand and Argentina indicate that the whale is relatively common in the areas south of those countries down to Antarctica. It has also been spotted close to South Georgia and South Africa, indicating a likely circumpolar distribution. The northernmost stranding was as 34 degrees south, indicating that whale inhabits cool and temperate as well as polar waters.

Baird's beaked whale is found in the North Pacific Ocean, the Sea of Japan and the southern part of the Sea of Okhotsk. They appear to prefer seas over steep cliffs at the edge of the continental shelf. Specimens have been recorded as far north as the Bering Sea and as far south as the Baja California peninsula on the east side and the southern islands of Japan on the west.

The total population is not known for either species. Estimates for Baird's are of the order of 30,000 individuals.

Behaviour

Little is known about the behavior of Arnoux's beaked whale but is expected to be similar to that of Baird's. The whales normally move in close-knit groups of about 3-10, with groups of 50 observed in exceptional circumstances. Considering the extent of whaling of the Baird's species, the pod structure is not well known. One interesting curiosity is that two-thirds of all whales caught have been male, despite the fact that females are somewhat larger than males and would be the preferred targets for whalers.

Conservation

Arnoux's beaked whale has rarely been exploited and although no abundance estimates are available, the population is not believed to be endangered.

In the twentieth century Baird's beaked whales were hunted primarily by Japan and to a lesser extent by the USSR, Canada and the United States. The USSR reported killing 176 individuals before hunting ended in 1974. Canadian and American whalers killed 60 before halting in 1966. Japan killed around 4000 individuals before the 1986 moratorium on whaling. 300 were killed in the most prolific year, 1952. Baird's beaked whales are not protected under the International Whaling Commission's moratorium on commercial whaling, as Japan argues that they are a 'small cetacean' species, despite being larger than minke whales, which are protected. Each year 62 Baird's beaked whales are hunted commercially in Japan, with the meat sold for human consumption. A landing and processing of a Baird's beaked whale was filmed[4] by the Environmental Investigation Agency on 07 August 2009. Meat and blubber food products of the whales have been found to contain high levels of mercury and other pollutants such as PCBs. The conservation status of Baird's beaked whales is not known globally [1] however the Mammalogical Society of Japan lists them as rare in Japanese coastal waters.

Common names

  • B. arnuxii Arnoux's Beaked Whale, Southern Four-toothed Whale, Southern Beaked Whale, New Zealand Beaked Whale, Southern Giant Bottlenose Whale, Southern Porpoise Whale
  • B. bairdii Baird's Beaked Whale, Northern Giant Bottlenose Whale, North Pacific Bottlenose Whale, Giant Four-toothed Whale, Northern Four-toothed Whale, North Pacific Four-toothed Whale

Specimens

  • MNZ MM002654 B. arnuxii Arnoux's Beaked Whale, collected Riverton, near Invercargill, New Zealand, 27 January 2006.

References

  1. ^ a b 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 bairdii In: IUCN 2009. IUCN Red List of Threatened Species. Version 2009.2. www.iucnredlist.org Retrieved on 07 February 2010.
  2. ^ McCann (1975). "A study of the genus Berardius". The Scientific Reports of the Whales Research Institute (Tokyo, Japan: Whales Research Institute) 27: 111–137. ISSN 0083-9086. 
  3. ^ "Origin of the name of Arnoux's beaked whale". http://www.cetacea.org/arnouxs.htm. 
  4. ^ "Video: Aftermath of a Japanese whale hunt". http://www.newscientist.com/article/dn17567-video-aftermath-of-a-japanese-whale-hunt.html. Retrieved 17 July 2010. 
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