Indian Ocean Sighting of Shepherd’s Beaked Whale (Tasmacetus shepherdi) Helps Confirm Circumpolar Distribution in Southern Hemisphere

Abstract

The Shepherd's beaked whale (Tasmacetus shep-herdi) is among the least known cetacean species in the world (Mead, 2002). It was first described in 1937 based on a specimen found stranded in New Zealand in 1933 (Oliver, 1937). The specimen was unique among beaked whales in that it had full sets of interlocking teeth along both jaws and was subsequently placed in its own genus due to this and other unique skull characteristics (Oliver, 1937). Other specimens collected from New Zealand in 1933, 1951, and 1962 were identified as T. shepherdi based largely on skull and mandible morphology (Oliver, 1937; Sorensen, 1940; Smith, 1965; Gaskin, 1968). T. shepherdi specimens were also discovered in Chile in 1970 (Brownell et al., 1976) and in Argentina in 1973, 1977, and 1978 (Mead & Payne, 1975; Goodall, 1978), thus expanding the known range of this species from the western South Pacific to the eastern South Pacific and western South Atlantic, respectively.