Shepherd's beaked whale

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Shepherd's beaked whale
Tasmacetus shepherdi.jpg
Shepherd's beaked whale size.svg
Size compared to an average human
CITES Appendix II (CITES) [2]
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Family: Ziphiidae
Genus: Tasmacetus
Oliver, 1937
Species:
T. shepherdi
Binomial name
Tasmacetus shepherdi
Oliver, 1937
Cetacea range map Shepherd 27s Beaked Whale.png
Shepherd's beaked whale range

Shepherd's beaked whale (Tasmacetus shepherdi), also commonly called Tasman's beaked whale or simply the Tasman whale, is a cetacean of the family Ziphiidae and the only species in the genus Tasmacetus. The whale has not been studied extensively. Only four confirmed at sea sightings have been made and 42 strandings recorded (as of 2006). It was first known to science in 1937, being named by W. R. B. Oliver after George Shepherd, curator of the Wanganui Museum, who collected the type specimen near Ohawe on the south Taranaki coast of New Zealand's North Island, in 1933. [3] [4]

Contents

Description

First underwater sighting of live Shepherd's beaked whales, near Inaccessible Island, Tristan da Cunha, January 2017. Tasmacetus shepherdi, Inaccessible Island, Tristan da Cunha, January 27, 2017.png
First underwater sighting of live Shepherd's beaked whales, near Inaccessible Island, Tristan da Cunha, January 2017.

Adults can reach lengths of 6 metres (20 ft) to 7.1 metres (23 ft) and weigh about 2.32 to 3.48 tons. At birth they may be about 3 metres (9.8 ft) long.

They are robust and large-bodied for beaked whales, having a bluff melon and a long, dolphin-like beak. [5]

It is the only species of ziphiid with a full set of functional teeth (17 to 27 pairs in both the upper and lower jaws). [4] Adult males also have a pair of tusks at the tip of the lower jaw.

They are dark brown dorsally and cream-colored ventrally, with a pale band extending up from the flipper and another pale area extending as a swathe on the posterior flank. The tall, falcate dorsal fin is set about two-thirds the way along the back. [5]

Population and distribution

Sightings and stranding records indicate that the species has a circumpolar distribution in southern hemisphere. [6] No population estimates exist for Shepherd's beaked whale. As of 2006, there have been about 42 stranding records of the species from New Zealand (including the Chatham Islands, 24), Argentina (7), Tristan da Cunha (6), Australia (3), and the Juan Fernández Islands (2). The northernmost record was at Shark Bay in Western Australia in 2008. [7] There have been five unconfirmed sightings (mostly from New Zealand), as well as a "probable" sighting near Shag Rocks and four confirmed sightings—the first two confirmed sightings occurred in 1985, within a few minutes of each other, off the Tristan da Cunha group (first sighting at 37°18′S12°32′W / 37.300°S 12.533°W / -37.300; -12.533 ); the third in 2002 near Gough Island ( 40°19′S9°53′W / 40.317°S 9.883°W / -40.317; -9.883 ); and the fourth in 2004 south of Tasmania ( 48°50′S150°06′E / 48.833°S 150.100°E / -48.833; 150.100 ). [8] In January 2012, a group of up to a dozen of this species were photographed and filmed by the Australian Antarctic Division south of Portland, Victoria. [9]

Multiple sightings of the species have been reported from Otago submarine canyons off Otago coast, New Zealand. Sightings have been recorded throughout the year with vocalization recordings, suggesting regular presences there. [10] These include at least two sightings in 2016 which were the first confirmed sightings within New Zealand waters, [11] followed by four sightings in 2017, [12] [13] one or more sighting(s) in 2018, [14] [15] one sighting in 2019, [16] four or five sightings in 2021, [17] [18] [19] [20] [21] five sightings in 2022 including a pod of 15-20 animals. [10] [22] [23] [24]

There have been additional sightings from other parts of New Zealand, such as off Gisborne, [25] several sightings off Kaikōura, [26] [27] [28] off Fiordland, [29] Taranaki, [30] and so on.

Behaviour

Four of the confirmed sightings of this species involved three to six individuals (one group included a calf) in waters from 350 metres (1,150 ft) to 3,600 metres (11,800 ft) deep, while a 2012 sighting involved as many as ten to twelve individuals. The animals surfaced several times, before arching to dive. Some were observed to come to the surface at a steep angle like many other ziphiids, raising their head and beaks out of the water. [8] The Shepherd's beaked whale's blow could be observed with the naked eye at a distance of up to 1,000 metres, within a bushy plume that is relatively tall for a ziphiid varying from 1 to 2 metres in height [31]

The species is seldom seen because of its deep, offshore distribution in waters where sighting conditions can be difficult (the "Roaring Forties" and "Furious Fifties"). [8]

Research done on a stranded individual's stomach has indicated that Shepherd's beaked whales eat both fish and squid, as opposed to most beaked whales which only eat cephalopods. [32]

Conservation

There are no reports of this species being hunted or killed accidentally by humans. Shepherd's beaked whale is covered by the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MOU). [33]

Taxonomy

Its nearest relative, the only other living member of the subfamily Ziphiinae, is Cuvier's beaked whale (Ziphius cavirostris).

See also

Related Research Articles

Beaked whales are a family of cetaceans noted as being one of the least-known groups of mammals because of their deep-sea habitat, reclusive behavior and apparent low abundance. Only three or four of the 24 existing species are reasonably well-known. Baird's beaked whales and Cuvier's beaked whales were subject to commercial exploitation, off the coast of Japan, while the northern bottlenose whale was extensively hunted in the northern part of the North Atlantic in the late 19th and early 20th centuries.

<span class="mw-page-title-main">Dusky dolphin</span> Species of mammal

The dusky dolphin is a dolphin found in coastal waters in the Southern Hemisphere. Its specific epithet is Latin for "dark" or "dim". It is very closely genetically related to the Pacific white-sided dolphin, but current scientific consensus holds they are distinct species. The dolphin's range is patchy, with major populations around South America, southwestern Africa, New Zealand, and various oceanic islands, with some sightings around southern Australia and Tasmania. The dusky dolphin prefers cool currents and inshore waters, but can also be found offshore. It feeds on a variety of fish and squid species and has flexible hunting tactics. The dusky dolphin is known for its remarkable acrobatics, having a number of aerial behaviours. The status of the dolphin is unknown, but it has been commonly caught in gill nets.

<span class="mw-page-title-main">Sowerby's beaked whale</span> Species of mammal

Sowerby's beaked whale, also known as the North Atlantic or North Sea beaked whale, is a species of toothed whale. It was the first mesoplodont whale to be described. James Sowerby, an English naturalist and artist, first described the species in 1804 from a skull obtained from a male that had stranded in the Moray Firth, Scotland, in 1800. He named it bidens, which derives from the two teeth present in the jaw, now known to be a very common feature among the genus.

<span class="mw-page-title-main">Hubbs' beaked whale</span> Species of mammal

Hubbs' beaked whale was initially thought to be an Andrews' beaked whale when discovered by ichthyologist Carl Hubbs; however, it was named in his honor when it was discovered to be a new species. This species has the typical dentition found in the genus, but its main outstanding features are a white "cap" on the head and very extensive scarring. The species is known from 31 strandings, a few at-sea sightings, and observations of two stranded whales that were kept in captivity for 16–25 days.

<span class="mw-page-title-main">Gervais's beaked whale</span> Species of whale

Gervais's beaked whale, sometimes known as the Antillean beaked whale, Gulf Stream beaked whale, or European beaked whale is the most frequently stranding type of mesoplodont whale off the coast of North America. It has also stranded off South America and Africa.

<span class="mw-page-title-main">Ginkgo-toothed beaked whale</span> Species of mammal

The ginkgo-toothed beaked whale is a poorly known species of whale even for a beaked whale, and was named for the unusual shape of its dual teeth. It is a fairly typical-looking species, but is notable for the males not having any scarring.

<span class="mw-page-title-main">Gray's beaked whale</span> Species of mammal

Gray's beaked whale, sometimes known as Haast's beaked whale, the scamperdown whale, or the southern beaked whale, is one of the better-known members of the genus Mesoplodon. This species is fairly gregarious and strands relatively frequently for a beaked whale. In the Māori language, this species is called hakurā or iheihe.

<span class="mw-page-title-main">Hector's beaked whale</span> Species of mammal

Hector's beaked whale, 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. The species has rarely been seen in the wild.

<span class="mw-page-title-main">Strap-toothed whale</span> Species of whale

The strap-toothed beaked whale, also known as Layard's beaked whale, is one of the largest members of the mesoplodont genus, growing to 6.2 m (20 ft) in length and reaching up to 1,300 kg (2,900 lb). The common and scientific name was given in honor of Edgar Leopold Layard, the curator of the South African Museum, who prepared drawings of a skull and sent them to the British taxonomist John Edward Gray, who described the species in 1865.

<span class="mw-page-title-main">True's beaked whale</span> Species of mammal

True's beaked whale is a medium-sized whale in the genus Mesoplodon. It is native to the northern Atlantic Ocean. The common name is in reference to Frederick W. True, a curator at the United States National Museum.

<span class="mw-page-title-main">Tropical bottlenose whale</span> Species of mammal

The tropical bottlenose whale, also known as the Indo-Pacific beaked whale or Longman's beaked whale, was considered to be the world's rarest cetacean until recently, but the spade-toothed whale now holds that position. As of 2010, the species is now known from nearly a dozen strandings and over 65 sightings. This is the only species in the genus Indopacetus.

<span class="mw-page-title-main">Pygmy beaked whale</span> Species of mammal

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<i>Berardius</i> Genus of mammals

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<span class="mw-page-title-main">Arnoux's beaked whale</span> Species of whale

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<span class="mw-page-title-main">Southern right whale dolphin</span> Species of mammal

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<span class="mw-page-title-main">Cetacean stranding</span> Phenomenon in which a whale becomes stuck on a beach, often causing the whales death

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<span class="mw-page-title-main">Southern bottlenose whale</span> Species of mammal

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<span class="mw-page-title-main">Whale watching in New Zealand</span>

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References

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  32. Best, P.B.; Smale, M.J.; Glass, J.; Herian, K.; Von Der Heyden, S. (2014). "Identification of stomach contents from a Shepherd's beaked whale Tasmacetus shepherdi stranded on Tristan da Cunha, South Atlantic". Journal of the Marine Biological Association of the United Kingdom. 94 (6): 1093–1097. doi:10.1017/s0025315412001658. hdl: 2263/42919 . S2CID   55181638.
  33. Official webpage of the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region

Sources

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