Long-finned pilot whale

Habitat: Deep temperate and subpolar waters, 200 - 3000m depth. Occasionally enters coastal waters, fjords, bays.

Description: Long slender body becomes more robust with age. Colouration black or dark grey on back and flanks with 3 areas of lighter colouration, variable in extent and intensity, between chin and belly, patch behind dorsal fin extending to midpoint of body, and light grey stripe extending backwards from eye. Head is square, bulbous, extends over upper lip especially in older males. Each jaw holds 8 - 12 pairs of small peg-like teeth. Flippers are long, pointed, sickle-shaped. Dorsal fin fairly low, slightly forwards of midpoint (to front 1/3 on adult males), sickle-shaped to broad, hump on leading edge in males, usually black but sometimes grey. As the animal ages, dorsal fin becomes more rounded, less dolphin-like. Thick keel on tail stock, more pronounced on adult male. Flukes have concave trailing edge, deeply notched in centre.

Size: 4 - 5 m (max. 6m) females; 5.5 - 6 m (max. 8.5 m) males.

Lifespan: 40 - 50 years.

Distribution: Widespread in temperate offshore waters of the world. Most commonly observed whale species around British Isles in 1970s - early 1980s but relatively uncommon since then. Most sightings occur in northern Great Britain, west of Ireland, and in west English Channel. Sightings occur in all months of the year but most commonly seen November - January.

Diet and feeding: Mainly squid, also variety of fish. Diet varies with reproductive condition; lactating females in some populations eat greater proportion of fish.

Breeding: No distinct season, some evidence for slight peak in births in late winter to early spring. Gestation period 14 - 16 months; lactation period 22 months; calving interval 3 - 4 years. Estimates vary for age of sexual maturity, from 10 - 12 years (male) and 6 - 7 years (female) for shore-driven specimens in Newfoundland to 15 - 20 years (male) and 9 - 10 years (female) for shore-driven specimens from Faroes.

Conservation status and population: Listed by IUCN as lower risk / least concern. Surveys across N Atlantic in 1989 estimated 778,000 individuals, but coverage did not extend fully into British waters.

Organised drives have taken place for at least 11 centuries in Faroes, average annual catch 850 from 1709 to 1992; still continues. Other opportunistic drive fisheries have operated in Shetland, Orkney, Outer Hebrides, W Ireland until early 20th Century. Extensive fishery in Newfoundland 1947 - 1972. Small nubers taken by coastal Norwegian fishery, off W Greenland, and Iceland.

Accidental capture in fishing gear is a problem off USA and in British waters. Relatively high levels of PCBs found in stranded animals, also high levels of DDT, PBDE, mercury, cadmium (pilot what meat consumed in Faroes may exceed safe levels of toxicity in humans).

Pilot whales change vocalisations in vicinity of military sonar, but significance for this species unknown. Ship strikes also pose a threat.

Identification

Flippers proportionately longer than in false killer whale. Rarely breaches clear of water although may slap surface with tail. May rest motionless at surface. Dolphins may associate with pilot whale herds. Gregarious; herds of 20 - 40 common but groups of up to low thousands also known.

Vocalisations: Variety of whistles mainly at 3.4 - 4.7 kHz lasting 0.65 - 1 s, echolocation clicks of 0.1 - 100 kHz.