Killer Whale 

	Killer whale Épaulard Orcinus orca Other names: Orca

Description

Yves Poirier

• Tall, straight dorsal fin, particularly for the male (up to two metres in height)

• Robust body

• Large, rounded pectoral fins

• Characteristic black and white colouration

• White or light-grey saddle patch on back behind dorsal fin

When it surfaces: Its blow, which is barely visible, especially from a distance, can be two metres high. Its dorsal fin, situated in the middle of its back, appears simultaneously with its blow.

A cosmopolitan, opportunist super dolphin

The largest of the dolphins is present in all of the world’s oceans. Adaptable, it is able to take advantage of a wide variety of oceanographic conditions and food resources. It has developed specialized learning for hunting purposes. This trait has given the killer whale the ability to attack animals far larger than itself, particularly other marine mammals. Some populations are organized into tight-knit, life-long family units that have developed distinct dialects. The killer whale is also a television and film star, and is very popular in aquariums. Although the worldwide population of killer whales is hard to estimate, the species does not appear to be threatened.

Population, range and habitat

In the St. Lawrence: Killer whale visits to the St. Lawrence Gulf and Estuary are considered rare and sporadic; there have been only 20 documented sightings since the early 1980s. A group of four to five killer whales visited the Gulf of St. Lawrence and the Jacques-Cartier Strait regularly during the 1990s. The most recent sighting in the Estuary dates back to 2003 when two killer whales were observed off Les Bergeronnes. Documents dating back to the 1940s describe this species as abundant in the Estuary at the time.

Migration: The killer whale does not appear to embark on a seasonal north-south migration. However, movements have been noted, especially in the Arctic Ocean where they linger at the edge of the ice pack. They have been known to follow migrating whales in order to prey upon them.

Worldwide: Killer whales appear to be rare and dispersed throughout the North Atlantic. According to a study carried out in 2007—pending a COSEWIC evaluation set for 2009—, the minimum population estimate for the western North Atlantic is a mere 70 individuals. These whales do not form populations as they do along the West Coast of North America, from Alaska to Washington State, in the North Pacific. The killer whale is a cosmopolitan species, present in all seas and oceans. It is not limited by water temperature or depth. Killer whale gatherings are most often observed in cold-water areas with high food densities. Some scientists have divided killer whales into populations, sub-populations, and possibly even into separate species, based on morphological, ecological, genetic and behavioural differences.

Behaviour

At the surface: The killer whale is a fast, powerful swimmer that can reach speeds of up to 45 km/h when hunting. As with all dolphins, it is capable of aerial displays and exuberant leaps. Killer whales are known to porpoise, surf, leap and breach, landing on their backs or bellies. They also slap their tails and flippers against the surface and spyhop by bringing their bodies vertically out of the water as far as their pectoral fins. Killer whales are even capable of swimming backwards.

Social behaviour: Killer whales can be observed alone or in groups. Little is known about North Atlantic killer whales due to the population’s small size, extensive range and nomadic nature. One resident Pacific Ocean population of approximately 300 killer whales is known to live in stable matriarchal groups of two to three dozen at a time.

Vocal behaviour: The killer whale is very active when it comes to vocalizing. Its varied repertoire includes squeaking, whistling, growling, crying and echolocation clicks. Each family unit uses its own unique dialect to communicate and ensure group cohesion.

Reproduction

Females attain sexual maturity between 12 and 16 years of age, males between 10 and 17. Mating takes place year round, with peaks in the spring and fall. Gestation lasts from 15 to 18 months. Newborn calves begin to eat solid prey very early on, but continue to nurse until they are a year old. They are not totally weaned until the age of two.

About scientific research

Killer whales visits to the St. Lawrence are rare and anecdotal. The majority of research projects dealing with this species are carried out on eastern North Pacific populations, near Vancouver, British Columbia. Three distinct populations that swim these waters can be differentiated by their appearance, behaviour and genetic make-up. They are known as the residents, the nomads and the offshore populations. Dave Snow administers the killer whale photo-identification catalogue and database in Atlantic Canada for the waters around Newfoundland and Labrador. This database is available online at www.atlanticwhales.com.

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	Killer Whale