Indopacetus pacificus (Longman, 1926)

Russell A. Mittermeier & Don E. Wilson, 2014, Ziphiidae, Handbook of the Mammals of the World – Volume 4 Sea Mammals, Barcelona: Lynx Edicions, pp. 326-357 : 351

7.

Longman’s Beaked Whale

Indopacetus pacificus

French: Baleine-a-bec de Longman / German: Indopazifik-Schnabelwal / Spanish: Zifio de Longman

Other common names: Indo-Pacific Beaked Whale, Tropical Bottlenose Whale

Taxonomy. Mesoplodon pacificus Longman, 1926 .

Australia, Queensland, “found at Mackay.”

This species is monotypic.

Distribution. Throughout the warmest waters of the Indian and Pacific oceans, it has a cross-equatorial distribution occurring from as far N as the Arabian Sea, S India, Japan, and Mexico to as far S as South Africa and Australia; its occurrence appears to be relatively continuous within its distribution; it has not been recorded in the Atlantic Ocean.

Descriptive notes. Total length 565-650 cm; weight ¢.7500 kg (unconfirmed). Until the start of the 21* century, Longman’s Beaked Whale was only known, with any certainty, from two partial skulls, and even today little is known about its morphology because few stranded specimens have been studied. Sightings at sea do provide some basic information about what Longman’s Beaked Whale looks like, and it appears to be similar to the Southern Bottlenose Whale ( Hyperoodon planifrons ). Body of Longman’s Beaked Whale is spindle-shaped, with greatest girth around its midpoint. Flukes are wide in relation to body length, and tailstock is compressed laterally. Dorsal fin is small and set approximately two-thirds of the distance between tip of the beak and end of the tail. Coloration is typically dark brown, dark gray, or black. Rostrum and lower jaw form a short but well-defined beak, and there are two grooves on the throat. Dentition of Longman’s Beaked Whale is restricted to a single pair of tusks at the tip of the lower jaw. These teeth only erupt in males, where they form a pair of conical tusks.

Habitat. There is no specific information available for this species, but like all species of beaked whales, Longman’s Beaked Whale is restricted to deeper oceanic waters.

Food and Feeding. There is no specific information available for this species, but L.ongman’s Beaked Whale is presumed, like other beaked whale species, to feed on deepwater squid and fish species. In common with other species of beaked whales, feeding of Longman’s Beaked Whale is likely to occur at great depth, often over 500 m and possibly as deep as 3000 m or more. Foraging dives may be up to an hour in length.

Breeding. There is no information available for this species.

Activity patterns. There is no specific information available for this species, but if, as is the case in other species of beaked whales, it consumes relatively small prey, Longman’s Beaked Whales spend a large proportion (60-70%) of their time foraging.

Movements, Home range and Social organization. There is no specific information available for this species, but Longman’s Beaked Whale is one of only three species of beaked whales that occurs in large groups. Maximum group size is ¢.100 individuals, while the average group size is ¢.20 individuals. Nothing is known about composition of these groups.

Status and Conservation. CITES Appendix II. Classified as Data Deficient on The [UCN Red List. There are no estimates of global population size of Longman’s Beaked Whale. It is thought to be more abundant in the western part of its distribution, where water temperatures are warmer, but it does not appear to be a particularly common. It has been estimated that there may be ¢.1000 Longman’s Beaked Whales in waters around Hawaii and ¢.300 in the eastern North Pacific. Nothing is known about threats to Longman’s Beaked Whale, although potential threats include being killed as bycatch in driftnet fisheries, noise pollution, and ingestion of plastic debris.

Bibliography. Anderson et al. (2006), Dalebout et al. (2003), MacLeod et al. (2006), Mead (1989b), Pitman et al. (1999), Rice (1998).

Figures

1. Baird’s Beaked Whale (Berardius baiwrdu), 2. Arnoux’s Beaked Whale (Berardius arnuxu), 3. Cuvier’s Beaked Whale (Ziphius cavirostris), 4. Northern Bottlenose Whale (Hyperoodon ampullatus), 5. Southern Bottlenose Whale (Hyperoodon planifrons), 6. Shepherd’s Beaked Whale (Tasmacetus shepherd), 7. Longman’s Beaked Whale (Indopacetus pacificus), 8. Hubbs’s Beaked Whale (Mesoplodon carlhubbsi), 9. Stejneger’s Beaked Whale (Mesoplodon stejnegeri), 10. Pygmy Beaked Whale (Mesoplodon peruvianus), 11. Perrin’s Beaked Whale (Mesoplodon perrini), 12. True’s Beaked Whale (Mesoplodon marus), 13. Strap-toothed Whale (Mesoplodon layardii), 14. Hector’s Beaked Whale (Mesoplodon hectori)

Distribution. Throughout the warmest waters of the Indian and Pacific oceans, it has a cross-equatorial distribution occurring from as far N as the Arabian Sea, S India, Japan, and Mexico to as far S as South Africa and Australia; its occurrence appears to be relatively continuous within its distribution; it has not been recorded in the Atlantic Ocean.