Globicéphale noir de l’Atlantique
Globicephala melas
Calderon dolphin, pilot dolphin, pothead whale, American blackfish
Toothed whales (Odontoceti)
4 m to 5 m, up to 8 m
2 to 3.5 t
Highly gregarious
45 years for males, 60 year for females
5 to 10 minutes
Regular in the southern part of the Gulf
Subarctic and temperate waters of the Northern and Southern Hemispheres
Unknown, but abundant
Not at Risk
Even if they are only viewed occasionally in the St. Lawrence, encounters with these pilot whales are impressive. With its dark skin, massive body and prominent melon, the pilot whale doesn’t have the typical look of a dolphin. The pilot whale owes its name to the strandings sometimes involving several tens of individuals, whose gregarious nature seems to incite them to follow their group leader to an imminent death.
The long-finned pilot whale is a summer resident in the Gulf of St. Lawrence, especially off the Gaspé Peninsula and the East Coast of Newfoundland. In the St. Lawrence, this population is estimated at 1,600 individuals (as per aerial surveys of the Gulf conducted in 1995). Visits by this species into the Estuary are quite rare. A few strandings of isolated individuals have occurred in the St. Lawrence as well as a mass stranding in the Estuary in 1920. In October 2009, eight long-finned pilot whales became beached in the Magdalen Islands.
The migratory movements of this pilot whale species are poorly known. In the Northwest Atlantic, individuals have a tendency to gather offshore in winter and spring and move closer to the coasts and into the bays in summer and fall. These movements are synchronized with those of their prey. In the world: The pilot whale is present in temperate and subarctic waters of the North Atlantic and in the western part of the Mediterranean. The number of long-finned pilot whales in the Northwest Atlantic is estimated at 10,000 and at least several hundred thousand in the central and eastern Atlantic. Subspecies of the long-finned pilot whale are found in the circumpolar regions of the Southern Hemisphere. The smaller short-finned pilot whale (Globicephala macrorhynchus) is a distinct species which inhabits warm waters of both the Northern and Southern Hemispheres and which is observed off the shores of British Columbia.
In 1994, the long-finned pilot whale was assessed and deemed “not at risk” by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). This species is designated “data deficient” by the International Union for Conservation of Nature (IUCN), and is not listed under the American Endangered Species Act or the List of threatened or vulnerable species in Quebec under the Act Respecting Threatened or Vulnerable Species.
The long-finned pilot whale feeds essentially on squid and mackerel that it finds in the water column, though it will occasionally eat shrimp and other fish species (cod, plaice). It sometimes teams up with other species such as the Atlantic white-sided dolphin to hunt.
Long-finned pilot whales are relatively fast swimmers and can reach speeds of 35 km/h when being chased by a predator. Like dolphins, their swimming is characterized by successive leaps and bounds. They are capable of jumping out of the water, but rarely do so. They do not approach ships or play in their bow waves or wake. They often engage in spyhopping and lobtailing. When resting, they typically remain motionless at the surface.
Dives last 5 to 10 minutes on average, most often to depths in the range of 30 to 500 m, where the species’ prey is found. They can reach 1000 m and last as long as 15 minutes, however.
The long-finned pilot whale is highly gregarious. Herds of several hundred individuals dispersed across the ocean are composed of stable family units of 10 to 20 members. These units are formed around adult females and their offspring. Males generally leave the family unit to reproduce and later return to the group they were born into. There, they assume the role of protector against predators, which might explain their shorter life expectancy compared to females. During the mating period, males can inflict injury or even death on one another with bites and violent blows to the head. These large pods are characterized by a very high level of social cohesion. Mass strandings involving hundreds of individuals are not unheard of. Several theories exist to explain such occurrences. Are they caused by navigation error, an infectious or parasitic disease within the pod, an extreme behaviour of solidarity toward a group member that is sick, injured or in distress? This pilot whale species may also associate with groups of dolphins as well as with larger cetaceans.
The pilot whale has a highly varied and complex vocal repertoire, which consists of whistles, clicks, pulsing sounds, grunts, screams and buzzing noises. These sounds are used for communication between individuals and echolocation.
Males reach sexual maturity between 12 and 16 years of age and females, between the ages of 6 and 10. The breeding season takes place from April to September. Gestation lasts 12 months. Calves are nursed for 3 years.
At Nova Scotia’s Dalhousie University, the team of Hal Whitehead has been leading research projects on the long-finned pilot whale off the coast of Cape Breton since 1998. He manages a catalogue of over 1500 individuals photo-ID’d based on notches and marks on their dorsal fins. Analysis of acoustic recordings currently being conducted would shed light on whether or not dialects exist within the family units of this species, as they do in killer whales.
