Christmas Tree Worm

Short-Finned Pilot Whale

Scientific Classification

Common Name
short-finned pilot whale, shortfin pilot whale, Pacific pilot whale
Kingdom
Animalia
Phylum
Chordata
Class
Mammalia
Order
Cetacea
Family
Delphinidae
Genus Species
Globicephala (from Latin "globus" - round ball or globe; from Greek "kephale" - head) macrorhynchus (from Greek "macro" - enlarged; "rhynchus" - beak or snout)
There are two geographical forms of short-finned pilot whales off Japan, northern and southern, differing in external and cranial morphology. Their exact taxonomic status is unresolved, but they may represent separate species or subspecies.

Fast Facts

Description
Extremely similar in appearance to long-finned pilot whale (Globicephala melas). Black in color, some individuals possess a light gray or white patch on the chin. Lighter, gray markings shaped like an anchor present on the chest widening posteriorally. They have a muscular body with thick tail stock. Forehead bulges over beakless mouth. Skull of G. macrorhynchus is wider, shorter and has fewer teeth than G. melas. The dorsal fin is very large and set forward on the body. The pectoral flippers of G. macrorhynchus are more curved than G. melas and are approximately 1/6 the body length.
Male: Sexual dimorphism is pronounced; males are heavier than females and have much larger melons and dorsal fins
Size
3.6 to 7 m (12 to 24 ft.) in length
Dorsal fin height = 30 cm (11.8 in.)
Tail fluke expanse = 130 cm (51.2 in.)
Weight
Mature males are almost twice as heavy as mature females
Male: 1,260 to 3,150 kg (2,780 to 6,940 lbs.)
Female: 600 to 1,150 kg (1,320 tio 2,540 lbs.)
Diet
Pilot whales feed primarily on squid but will also take fish. Market Squid (Loligo sp.) is commonly taken off the California Coast. Short-finned Pilot Whales show the tooth reduction typical of other squid-eating cetaceans. This species feeds on vertically migrating prey, with deep dives at dusk and dawn following vertically migrating prey and near-surface foraging at night.
Gestation
15 months average
Nursing Duration
At least 2 years but will begin eating solid food at 6 to 12 months; calves have been known to nurse for 6 to 10 years.
The last calf born to a mother may be nursed for as long as 15 years.
Female have calves every 5 to 8 years.
Sexual Maturity
Male:  13 to 16 years at 4.2 to 5.5 m (13.8 to 18 ft.); males begin to mate successfully several years after achieving sexual maturity
Female: Between 7 to 12 years; average 9 years at 3.16 to 3.95 m (10.4 to 13 ft.); can remain reproductively active up to 37 years
Life Span
Male: Approximately 35 to 45 years;
Female: Up to 60 years
Large numbers of post-reproductive females have been identified in many populations. Males believed to have a higher mortality rate at all ages than females.
Range
Short-finned pilot whales are found in warm temperate to tropical waters of the world, generally in deep offshore areas They do not usually range north of 50°N or south of 40°S.
This species is not thought to inhabit the Mediterranean Sea, but it does occur in the southern Red Sea.
There is some distributional overlap with their long-finned relatives (G. melas), which appear to prefer cold temperate waters of the North Atlantic, Southern Hemisphere, and previously the western North Pacific. Only short-finned pilot whales are currently thought to inhabit the North Pacific.
The two geographic forms of short-finned pilot whale off Japan have different, but partially-overlapping, distributions. The range includes the Sea of Japan .
Habitat
These animals are found in deep waters, typically in highest densities over the outer continental shelf or continental slope. They occur in tropical to cool temperate waters.
Population
There are an estimated 589,000 short-finned pilot whales in the eastern tropical Pacific and an estimated 304 in waters off the North American west coast. In Hawaiian waters, there are estimated to be 8,846. The Gulf of Mexico contains at least 2,388 animals, and 31,139 pilot whales of both species are estimated to occur in the western North Atlantic.
The northern form off Japan has a subpopulation estimated at 4,000 to 5,000, and the southern form has an estimated subpopulation of about 14,000 in coastal waters.
Status 
IUCN: Data Deficient
CITES: Appendix II
USFWS: Not listed

Fun Facts

  1. The name "pilot whale" is believed to originate from the idea that the pods or herds were piloted by a leader whale.
  2. Pod structure reflects the highly social nature of pilot whales sharing close matrilineal relationships. Short-finned pilot whales live in stable groups of 15 to 30 animals comprised of family relatives, and tend to live in localized, resident populations, although some populations have wider ranges. All age ranges and both sexes are represented although among the adults, females are predominant. Genetic evidence does indicate however that the males breed outside of their family groups.
  3. The echolocation ability of pilot whales is equal to that of bottlenose dolphins (Tursiops truncatus). Vocalizations of short-finned pilot whales are in a higher frequency and wider frequency range than those of Long-finned Pilot Whales. They also exhibit group-specific calls.
  4. Maximum dive depth may be 500 m (1,640 ft.).
  5. The observed upper limit through which a pilot whale may remained submerged without surfacing to breath is 15 minutes. Typical submersion periods are generally several minutes below this upper threshold.

Ecology and Conservation

Short-finned pilot whales are generally nomadic. They are usually found on continental shelf break, slope waters and where there is high topographic relief and where squid is plentiful. Population studies off of California show that pilot whale groups where greatly affected by the reduced number of spawning squid during the El Niño event of 1982–83. The whales in that area were absent during the period and at least 9 years afterward.

Due to their strong herding behavior, pilot whales are targeted by drive fisheries for their meat, blubber and oil. They are also incidentally taken by drift net, purse-seining, trawling and long line fisheries. This bycatch is not well monitored so the affect on overall population figures is unknown.

Pilot whales are one of the most common species to engage in mass strandings. The cause of these events is not understood but may be the result of disease, illness or geomagnetic disorientation.

This species, like beaked whales, is likely to be vulnerable to loud anthropogenic sounds, such as those generated by navy sonar and seismic exploration. While conclusive evidence of cause and effect are often lacking, mass stranding events have been spatially and temporally associated with high levels of anthropogenic sound for short-finned pilot whales.


Bibliography

Leatherwood, Stephen, and Reeves, Randall R. The Sierra Club Handbook of Whales and Dolphins. San Francisco: Sierra Club Books, 1983.

Nowak, Ronald M. (ed.). Walkers Mammals of the World. Vol. II. Baltimore: Johns Hopkins University Press, 1999.

Perrin, W. F., Wursig, B., Thewissen, J. G. M. Eds. Encyclopedia of Marine Mammals. Academic Press, 2002.

Martin, A. R. The Ilustrated Encyclopedia of Whales and Dolphins. New York: Portland House, 1990.

http://www.fao.org

http://www.nmfs.noaa.gov/pr/PR2/Stock_Assessment_Program/Cetaceans/Short-Finned_Pilot_Whale_(N._Gulf_of_Mexico)/ao03shortfinnedpilotwhalengom.pdf

Taylor, B.L., Baird, R., Barlow, J., Dawson, S.M., Ford, J., Mead, J.G., Notarbartolo di Sciara, G., Wade, P. & Pitman, R.L. 2011. Globicephala macrorhynchus. The IUCN Red List of Threatened Species 2011: e.T9249A12972356. http://dx.doi.org/10.2305/IUCN.UK.2011-2.RLTS.T9249A12972356.en. Downloaded on 28 September 2018.

NOAA Fisheries – Short-finned Pilot Whale – Species Profile. https://www.fisheries.noaa.gov/species/short-finned-pilot-whale/. Downloaded on 28 September 2018.