Shepherd'S Beaked Whale

Adults can reach lengths of 6 m (20 ft) to 7.1 m (23 ft) and weigh about 2.32 to 3.48 tons. At birth they may be about 3 m (9.8 ft) long. The longest recorded lengths were 7 m (23 ft) for a male and 6.6 m (22 ft) for a female.

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

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). Adult males also have a pair of tusks at the tip of the lower jaw.

Sightings and stranding records indicate that the species has a circumpolar distribution in southern hemisphere. 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. 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′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).

Like other beaked whales, Shepherd’s beaked whales possess a pair of V-shaped throat grooves that are thought to facilitate suction feeding by creating negative pressure within the mouth as the tongue retracts and the throat grooves expand, powerfully drawing prey inward like a biological vacuum. They are presumed to use echolocation to locate prey and may also use vision at close range, particularly when targeting bioluminescent species. However, their unusual full set of functional teeth may also be advantageous in capturing fish, which constitute a substantial portion of their diet.

Four of the confirmed sightings of this species involved three to six individuals (one group included a calf) in waters from 350 m (1,150 ft) to 3,600 m (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. The Shepherd's beaked whale's blow could be observed with the naked eye at a distance of up to 1,000 m (3,300 ft), within a bushy plume that is relatively tall for a ziphiid varying from 1 to 2 m (3.3 to 6.6 ft) in height. Males tend to have light, linear scarring on their bodies. These are suggested to be the result of fighting with other males with their apical teeth or other unknown social behaviors within a pod.

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). Plastic debris and longline hooks have been found in the stomachs and intestines of some individuals, which could lead to internal trauma or starvation if the material blocks their digestive tracts.