Short-finned pilot whale (Globicephala macrorhynchus)

Description

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Short-finned pilot whale fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
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Short-finned pilot whale description

The short-finned pilot whale (Globicephala macrorhynchus) is relatively large member of the dolphin family (Delphinidae), and is known for its rather large, globular head. The globular shape of the head is more highly developed in males, and in old males can droop and come to hang over the mouth ^{(2) (4)}.

The body of the short-finned pilot whale is dark grey or black, with a light grey patch on the chin and underside, in the shape of an anchor ^{(4) (5) (6)}. This patch is lighter in younger animals ⁽⁵⁾. The short-finned pilot whale also has a light grey to white chevron just behind its head and another white patch underneath and behind its dorsal fin ^{(4) (6)}.

The dorsal fin of the short-finned pilot whale is sickle-shaped or curved, and is broad and thick. It measures around 30 centimetres in height and sits far forward on the body, usually lining up with the pectoral fins. The pectoral fins, or flippers, are also curved like a sickle and are narrow and tapering, measuring about one-fifth to one-sixth of the body length ^{(2) (6) (7) (8)}. This measurement is used to distinguish the short-finned pilot whale from the long-finned pilot whale, Globicephala melas (2), although the two species can still be difficult to tell apart at sea ⁽⁶⁾.

Most short-finned pilot whales have between seven and nine short, tough teeth on each side of the jaw, at the front of the mouth ⁽⁴⁾. The male short-finned pilot whale is longer and heavier than the female ^{(2) (6) (7)}, and also has a much larger dorsal fin ⁽⁶⁾.

Also known as

blackfish, Pacific pilot whale, pothead, shortfin pilot whale.

Synonyms

Globicephala scammoni.

French

Globicéphale Tropical.

Spanish

Caldrón Negro.

Size

Average male length: 5.5 m ⁽²⁾

Average female length: 4.3 m ⁽²⁾

Male weight: up to 3,000 kg ⁽²⁾

Female weight: up to 1,500 kg ⁽²⁾

Short-finned pilot whale biology

The short-finned pilot whale is usually found in groups of 10 to 60. It is a highly social animal, and larger herds numbering into the several hundreds have also been recorded. This species communicates through a variety of clicks, whistles, squeals, smacking, whining and ‘snores’, and it also uses echolocation ^{(4) (7) (8)}.

The typical diet of the short-finned pilot whale appears to consist of squid and fish, as well as other cephalopods, such as octopuses ^{(1) (4) (7) (8) (9)}. However, short-finned pilot whales have been reported to “harass” sperm whales and dolphins, so marine mammals may also potentially be included in their diet ⁽⁴⁾. This species usually feeds at night, making deep dives in search of prey ^{(1) (7)}.

The short-finned pilot whale does not seem to have a typical breeding season, and has been recorded breeding and giving birth in winter, spring and autumn. The gestation period lasts for a little over a year, and female short-finned pilot whales give birth about once every three years ^{(4) (8)}. Each female short-finned pilot whale will give birth to four or five calves during her lifetime ⁽²⁾. The newborn calf averages about 1.4 metres in length and weighs around 60 kilograms ^{(2) (4) (8)}, and may be suckled by the female for at least 2 years ⁽⁷⁾.

The short-finned pilot whale lives in a ‘matrilineal’, or female-based society, and older females have been known to care for a calf that is not their own ⁽⁴⁾. After weaning, young male short-finned pilot whales may move to a new group, whereas females tend to stay in the group into which they were born ⁽⁷⁾. Herds of this species usually consist of a small number of reproductive adult males, sometimes only one, with a greater number of adult females of all ages and reproductive status, plus immature calves of both sexes ^{(2) (7)}. The name “pilot whale” comes from an early idea that groups of these whales are piloted by a leader ⁽⁶⁾.

Female short-finned pilot whales reach sexual maturity at about 8 years of age, while males reach maturity later, at about 13 years. A typical male short-finned pilot whale will live for approximately 45 years and a typical female for about 55 years ⁽²⁾, although the female will usually stop reproducing after about 40 years old ⁽⁷⁾.

Short-finned pilot whale range

The short-finned pilot whale is found worldwide in offshore tropical, subtropical and warm temperate waters ^{(1) (4) (6) (7) (8)}. There are known populations in the North Atlantic, from the United States to northern South America, including the Gulf of Mexico, and east to Europe and Africa ^{(2) (4) (6)}. These populations are thought to move south during the spring and late winter into the western North Atlantic ⁽⁴⁾.

Other populations are found in the Pacific Ocean, from the Gulf of Alaska south to Guatemala ⁽²⁾. The short-finned pilot whale is also reported from the western North Pacific in the Sea of Japan, as well as in the southern Red Sea and the Indian Ocean ^{(1) (6) (7)}.

Two distinct populations of short-finned pilot whale found off northern and southern Japan show differences in their anatomy and genetics, and may potentially comprise more than one distinct species or subspecies. However, their exact taxonomy has yet to be confirmed ^{(1) (6)}.

Short-finned pilot whale habitat

The short-finned pilot whale prefers warm, deep waters, typically around the outer edges of the continental shelf ^{(1) (2)}. However, individuals may sometimes move towards the coast ⁽²⁾, even occasionally coming far enough inshore to become stranded ⁽⁸⁾.

Short-finned pilot whale status

The short-finned pilot whale is classified as Data Deficient (DD) on the IUCN Red List ⁽¹⁾ and is listed on Appendix II of CITES ⁽³⁾.

Short-finned pilot whale threats

The main threat to the short-finned pilot whale is bycatch, or incidental take in fisheries, with the whales often becoming caught in fishing equipment such as gillnets, longlines and trawls ⁽⁹⁾.

This species is also directly targeted by fisheries in Japan, the Caribbean and the Philippines. The largest numbers of short-finned pilot whales are taken off the coast of Japan ^{(1) (9)}.

In addition to these threats, the short-finned pilot whale may be vulnerable to loud human-made sounds, such as those generated by navy sonar and seismic exploration equipment ⁽¹⁾. Changes to the marine environment due to climate change may also potentially affect this species in the future ⁽¹⁾.

Due to its highly social nature, the short-finned pilot whale is particularly susceptible to stranding in large groups, although the reasons for this are not always clear ⁽⁷⁾.

Short-finned pilot whale conservation

In the United States, the short-finned pilot whale is included in the National Marine Fisheries Service (NMFS) Pacific Offshore Cetacean Take Reduction Plan. This plan requires that devices such as net alarms and ‘pingers’ (devices which emit sounds that deter dolphins and whales) be used in certain fisheries, to help reduce the accidental take of cetacean species ⁽⁹⁾.

In addition, the short-finned pilot whale is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), which means that any international trade in this species should be carefully controlled ⁽³⁾. Further research is needed into the impacts of various threats on the short-finned pilot whale, and its taxonomy also needs to be investigated, as it is possible that it may comprise more than one distinct species ⁽¹⁾.

View information on this species at the UNEP World Conservation Monitoring Centre.

Find out more

Find out more about the short-finned pilot whale and other marine mammals:

• Convention on Migratory Species - Globicephala macrorhynchus:
  http://www.cms.int/reports/small_cetaceans/data/G_macrorhynchus/g_macrorhynchus.htm
• Jefferson, T.A., Leatherwood, S. and Webber, M.A. (1993) FAO Species Identification Guide. Marine Mammals of the World. FAO, Rome. Available at:
  http://nlbif.eti.uva.nl/bis/marine_mammals.php?menuentry=inleiding

More information on whale and dolphin conservation:

• Whale and Dolphin Conservation Society:
  http://www.wdcs.org/index2.php

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Glossary

Bycatch

In the fishing industry, the part of the catch made up of non-target species.

Cephalopod

From the Greek for ‘head-foot’, a class of molluscs that occur only in marine habitats. All species have grasping tentacles, and either an internal or external shell. Includes nautiloids, cuttlefish, squids, octopuses, and extinct ammonites and belemnites.

Cetacean

A whale, dolphin or porpoise.

Continental shelf

A region of relatively shallow water, not usually deeper than 200 metres, surrounding each of the continents.

Dorsal fin

The unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans (whales, dolphins and porpoises).

Echolocation

Detecting objects by reflected sound. Used by bats and odontocete cetaceans (toothed whales, dolphins and porpoises) for orientation and to detect and locate prey.

Gestation

The state of being pregnant; the period from conception to birth.

Pectoral fins

In cetaceans (whales, dolphins and porpoises), the paddle-like pair of limbs, also known as ‘flippers’, found on either side of the body and used for balance and steering.

Subspecies

A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.

Taxonomy

The science of classifying organisms, grouping together animals which share common features and are thought to have a common ancestor.

References

1. IUCN Red List (February, 2012)
   http://www.iucnredlist.org/
2. Wilson, D.E. and Ruff, S. (1999) The Smithsonian Book of North American Mammals. Smithsonian Institution Press, Washington, D.C.
3. CITES (February, 2012)
   http://www.cites.org/
4. Würsig, B.G., Jefferson, T.A. and Schmidly, D.J. (2000) The Marine Mammals of the Gulf of Mexico. TexasA&M University Press, College Station, Texas.
5. Macdonald, D.W. (2006) The Encyclopedia of Mammals. Oxford University Press, Oxford.
6. Olson, P.A. (2002) Pilot whales Globicephala melas and G. macrorhynchus. In: Perrin, W.F., Würsig, B. and Thewissen, J.G.M. (Eds.) Encyclopedia of Marine Mammals. Academic Press, San Diego, California.
7. Nowak, R.M. (1991) Walker’s Mammals of the World. The Johns Hopkins University Press, Baltimore and London.
8. Schmidly, D.J. (1994) The Mammals of Texas. University of Texas Press, Austin, Texas.
9. NOAA Fisheries: Office of Protected Resources - Short-finned pilot whale (February, 2012)
   http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/pilotwhale_shortfinned.htm