| Shepherd's beaked whale | |
|---|---|
| Size comparison against an average human | |
| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Cetacea |
| Family: | Ziphiidae |
| Subfamily: | Ziphiinae |
| Genus: | Tasmacetus |
| Binomial name | |
| Tasmacetus shepherdi Oliver, 1937 |
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| 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 Ziphidae. The whale has been little studied. 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, former curator of the Wanganui Museum, who collected the type specimen near Ōhawe on the south Taranaki coast, North Island, New Zealand, in 1933.[2][3]
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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.[4] 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).[3] 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.[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). 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 year, off the Tristan da Cunha group (first sighting at 37°18'S, 12°32'W); the third in 2002 near Gough Island (40°19'S, 9°53'W); and the fourth in 2004 south of Tasmania (48°50'S, 150°06'E).[5]
The few 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. The animals surfaced several times, giving a "small, bushy" blow (only visible from the aerial sightings), 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.[5]
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").[5]
There are no reports of this species being hunted or killed accidentally by humans.