A SIGHTING OF SHEPHERD’S BEAKED WHALES
TASMACETUS SHEPHERDI
AT SEA OFF GOUGH ISLAND, SOUTH ATLANTIC (CETACEA: ZIPHIIDAE)

On the early morning of 27 October 2002 the M/S Explorer was nearing an intended anchorage in Quest Bay, Gough Island in the South Atlantic. I was aboard in my capacity as a specialist guide for a British birding and wildlife tour company.

Our position was 40º19’S 09º53’W, sea conditions were ‘slight, low swell with waves at 2 feet’ (60 cm.). I saw a small pod of whales ahead of us, about 60 metres distance. There were four or five smallish whales, one was judged to be approx. 6 metres length, which began powering away from our approach at a fast constant pace on our port side. They obviously belonged to the Ziphiidae, the beaked whale family. Through binoculars I was immediately struck by the contrast on the head of the leading whale. Although accentuated by sunlight it showed an obvious very pale grey forehead and crown. The colour may have extended past the blowhole, and contrasted to the dark back. I panned to another of the group but did not see the same strong contrast on the head of this second whale, so went back to the first, trying to see as much as possible on the more distinct animal. Surfacing was regular and the beak would come clear of the water at an angle of about 40º. The beak was dark and well defined, reminding me in general shape and prominence to that of a Common Dolphin Delphinus delphis, but this whale had a steep forehead and it was now clear to me that it was the melon itself that was much lighter in colour than the back. The dorsal fin was small and curved, at no time did the body sides show, nor were there any noticeable blows visible from members of the pod.

A selection of field-guides was kept on the bridge and I immediately went to these to identify the species. One of the ship’s onboard naturalists was already there, thumbing through the cetacean books. Between us we had field experience of many species including various beaked whales of the Southern Oceans and it became clear that we had seen broadly the same field marks. Amongst the literature aboard were Carwardine (1995), Leatherwood and Reeves (1983) and Folkens et al. (2002). Only in the last did we find a plate that showed a likeness to our whales. It was Shepherd’s Beaked Whale Tasmacetus shepherdi, but as there was so much discrepancy in the available literature we were unsure if this was an accurate depiction or not.  We were able to eliminate the other larger temperate beaked whales such as the Straptoothed Whale Mesoplodon layardii, Cuvier’s Beaked Whale Ziphius cavirostris, and Arnoux’s Beaked Whale Berardius arnuxii by consideration of the size and shape of the beak, and the shape of the melon and its colouration.

On returning to England I put the trip report onto a webpage (Pym 2003) and was contacted by Dr Alan Baker of the Department of Conservation in New Zealand who was interested in the claim of Tasmacetus shepherdi. I sent him notes and a sketch, here included, and he believed we had eliminated all other known beaked whales by the combination of features described above. He arranged for Anton van Helden at the Museum of New Zealand to send me his excellent drawings of Tasmacetus shepherdi based on two fresh stranded New Zealand specimens, a juvenile male and an adult male. When I saw these, the first portrayal I knew to be accurate, I was convinced we had correctly identified the whales and that the lead animal was probably an adult male.

There have been some thirty strandings in total of Shepherd’s Beaked Whales from Argentina, Chile, Tristan da Cunha, South Africa, Australia, with the majority from New Zealand (Dr Alan Baker, pers.comm.). Prior to this record there had been only one documented observation of a lone probable Shepherd’s Beaked Whale (Watkins 1976), in New Zealand waters, and two further putative sight records from Western Australia and the western South Atlantic.

ACKNOWLEDGEMENTS

My thanks to Dr Alan Baker for his adjudication of this record and the suggestion of this note, and Anton van Helden for kindly sending me his drawings.

LITERATURE CITED

Carwardine M. 1995. Whales, Dolphins and Porpoises. Dorling Kindersley Ltd., London

Folkens P., Randall R. Reeves, Brent S. Stewart, Phillip J.Clapham, James A. Powell. 2002. National Audubon Society Guide to Marine Mammals of the World. Alfred A Knopf, Inc., New York

Leatherwood, S., and R.R. Reeves. 1983. The Sierra Club Handbook of Whales and Dolphins. Sierra Club Books, San Francisco, CA.

Pym A. (Tony) 2003. A Seabirding Adventure with Ornitholidays SeabirdingAtlanticOcean.html

Watkins, W. A. 1976. A probable sighting of a live Tasmacetus shepherdi in New Zealand waters. J. Mamm. 57:415

A. (TONY) PYM, Hurley Stream Cottage, Southcott, Pewsey, Wiltshire, SN9 5JF, England
UPDATE
(July 2006)
A joint paper (Pitman, van Helden, Best and Pym) titled:
  
Shepherd’s Beaked Whale (Tasmacetus shepherdi): Information on Appearance and Biology
Based on Strandings and At-sea Observations

has now been published in the journal Marine Mammal Science. To read the full paper (pdf file) click here!

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