Shepherd's beaked whale explained

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.[1] [2]

Description

Adults can reach lengths of to and weigh about 2.32 to 3.48 tons. At birth they may be about long.

They are robust and large-bodied for beaked whales, having a bluff melon and a long, dolphin-like beak.[3]

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).[2] 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.[3]

Population and distribution

Sightings and stranding records indicate that the species has a circumpolar distribution in southern hemisphere.[4] 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.[5] 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 -37.3°N -44°W); the third in 2002 near Gough Island (-40.3167°N -62°W); and the fourth in 2004 south of Tasmania (-48.8333°N 156°W).[6] 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.[7]

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. These include at least two sightings in 2016 which were the first confirmed sightings within New Zealand waters,[8] followed by four sightings in 2017,[9] [10] one or more sighting(s) in 2018,[11] [12] one sighting in 2019,[13] four or five sightings in 2021,[14] [15] [16] [17] [18] five sightings in 2022 including a pod of 15-20 animals.[19] [20] [21] [22]

There have been additional sightings from other parts of New Zealand, such as off Gisborne,[23] several sightings off Kaikōura,[24] [25] [26] off Fiordland,[27] Taranaki,[28] 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 to 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.[6] 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 [29]

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").[6]

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.[30]

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).[31]

Taxonomy

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

See also

Sources

  1. Shepherd's beaked whale in the Encyclopedia of Marine Mammals Thomas A. Jefferson, 1998.
  2. Whales, Dolphins and Porpoises Carwardine, 1995.

Notes and References

  1. http://www.teara.govt.nz/en/whales/7/2 Te Ara Encyclopedia - Beaked whales – George Shepherd
  2. Book: Guide to Marine Mammals of the World. Reeves, R.. Stewart, B.. Clapham, P.. Powell, J.. amp. 318–321. 2003. 0-375-41141-0. A.A. Knopf. New York. registration.
  3. Book: Whales, Dolphins and Other Marine Mammals of the World. Shirihai, H. . Jarrett, B. . amp . Princeton Field Guides. 2006. 43–45. 0-691-12757-3. 73174536.
  4. Jared R. Towers, Paul Tixier, 2022, Indian Ocean Sighting of Shepherd’s Beaked Whale (Tasmacetus shepherdi) Helps Confirm Circumpolar Distribution in Southern Hemisphere, Aquatic Mammals, 48(5), pp.462-467
  5. Carly Holyoake, Dave Holley, Peter B. S. Spencer, Chandra Salgado Kent, Doug Coughran, Lars Bejder, 2013, Northernmost record of Shepherd's beaked whale (Tasmacetus shepherdi) - A morphological and genetic description from a stranding from Shark Bay, Western Australia, Pacific Conservation Biology, 19 (2), pp.169-174, DOI:10.1071/PC130169
  6. Pitman R.L., van Helden A.L., Best P.B., Pym A. . 2006 . Shepherd's beaked whale (Tasmacetus shepherdi): information on appearance and biology based on strandings and at-sea observations . Mar. Mammal Sci.. 22 . 3. 744–755 . 10.1111/j.1748-7692.2006.00066.x.
  7. Australian Antarctic Program, 2012, Whale trackers make rare sighting, Australian Antarctic Division, Retrieved on August 07, 2022
  8. John Gibb, 2016, Sighting of beaked whale a first, Otago Daily Times, Retrieved on August 07, 2022
  9. Vaughan Elder, 2017, Population of whales off Dunedin coast significant, study finds, The Otago Daily Times, Retrieved on September 02, 2021
  10. New Zealand Whale and Dolphin Trust, 2017, December 14th, 2017 on Facebook, Retrieved on September 13, 2022
  11. Steve Wood, 2018, Otago Canyon Pelagic - Sept 29th., BirdingNZ, Retrieved on August 07, 2022
  12. New Zealand Whale and Dolphin Trust, 2019, June 29th, 2019 on Facebook, Retrieved on September 13, 2022
  13. David Donnelly, Marine Research, 2019, November 30th, 2019 on Facebook, Retrieved on September 13, 2022
  14. oscarkokako, 2021, Shepherd's beaked whale (Tasmacetus shepherdi), iNaturalist, Retrieved on August 07, 2022
  15. Oscar Thomas, 2021, Moeraki Pelagics to Otago Canyons / Saturday 3rd and Sunday 4th July 2021, BirdingNZ, Retrieved on August 07, 2022
  16. Project Jonah New Zealand, 2021, October 31st, 2021 on Instagram, Retrieved on September 13, 2022
  17. Warwick Allen, Bobby Phuong, 2021, October 21, 2021 on Instagram, Retrieved on September 13, 2022
  18. Peter Langlands, 2021, December 30th, 2021 on Facebook, Retrieved on September 13, 2022
  19. Hamish MacLean, 2022, Rare whales seen, vocalisation recorded, The Otago Daily Times, Retrieved on February 24, 2022
  20. adamduchac, 2022, Shepherd's beaked whale (Tasmacetus shepherdi), iNaturalist, Retrieved on August 07, 2022
  21. Annie Ching, 2022, January 13th, 2022 on Facebook, Retrieved on September 13, 2022
  22. Oscar Thomas, 2022, Moeraki Pelagics Nov 12/13 Report, BirdingNZ, Retrieved on November 15, 2022
  23. [Gisborne Herald]
  24. [The New Zealand Herald]
  25. Whale Watch Kaikoura, 2018, The Rarest of the World's Whales - Spotted Twice whilst Whale Watching, Retrieved on August 07, 2022
  26. Alan Granville, 2019, 'Extraordinary': Exceptionally rare whale visits Kaikōura, Stuff, Retrieved on August 07, 2022
  27. hannahwilllliams, 2022, Shepherd's beaked whale (Tasmacetus shepherdi), iNaturalist, Retrieved on August 07, 2022
  28. Saltwater iv, 2017, Very Rare Shepherd's Beaked Whale - Tasmacetus shepherdi _ Taranaki New Zealand on Youtube, Retrieved on September 13, 2022
  29. Donnelly. David M.. Ensor. Paul. Gill. Peter. Clarke. Rohan H.. Evans. Karen. Double. Michael C.. Webster. Trudi. Rayment. Will. Schmitt. Natalie T.. July 2018. New diagnostic descriptions and distribution information for Shepherd's beaked whale (Tasmacetus shepherdi) off Southern Australia and New Zealand: DESCRIPTIONS AND DISTRIBUTION FOR T. SHEPHERDI. Marine Mammal Science. en. 34. 3. 829–840. 10.1111/mms.12478.
  30. 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. 10.1017/s0025315412001658. 2263/42919. 55181638 . free.
  31. http://www.pacificcetaceans.org/ Official webpage of the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Shepherd's beaked whale".

Except where otherwise indicated, Everything.Explained.Today is © Copyright 2009-2024, A B Cryer, All Rights Reserved. Cookie policy.