Killer Whale

In the St. Lawrence

With about 20 or so observations since the early 1980s, killer whale visits are rare and sporadic in the Gulf and in the Estuary. In the 1990s, a group of 4 or 5 killer whales regularly visited the Gulf and the Jacques Cartier Strait. The most recent observation in the Estuary goes back to 2003, when two killer whales were seen off the coast of Les Bergeronnes. The most recent observation in the Gulf goes back to 2014. Documents from the 1940s mention that killer whales were abundant in the Estuary at that time.

Migration

Killer whales do not seem to undertake any seasonal north-south migration. However, movements are observed, notably in the Arctic where the species stays close to the edge of the pack ice. They are also known to follow migrating whales that they prey upon.

In the world

In the North Atlantic, killer whales are apparently few in number and scattered. According to a review conducted in 2007 (pending an evaluation scheduled for 2009 by the COSEWIC), the minimum estimate of the Northwest Atlantic population is 70 individuals. They are not grouped into distinct populations, as they are in the North Pacific along the west coast of North America (from Alaska to Washington State). Unconstrained by temperature or water depth factors, the killer whale is a cosmopolitan species which is present in all of the world’s seas and oceans. Nevertheless, killer whales are observed to be concentrated in cold water areas with abundant food resources. According to some scientists, morphological, ecological, genetic and behavioural differences observed in killer whales may divide them into populations, sub-populations, and possibly even different species.

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) had classified the killer whale population of the Northwest Atlantic and Eastern Arctic as “data deficient” in 2001. In November 2008, a new status report classified this population as “special concern”. Whaling in Greenland, shipping traffic and contaminants are the main threats faced by this population. The small size of the population, its vital cycle and its social characteristics also make it more fragile. The International Union for Conservation of Nature (IUCN) has listed the species as “data deficient”. The killer whale of the Northwest Atlantic is not included in the List of Endangered and Threatened Wildlife under the American Endangered Species Act, nor in the List of threatened or vulnerable species in Quebec under the Act Respecting Threatened or Vulnerable Species.

Feeding

Killer whales have a highly varied diet, feeding on small schooling fish, squid, turtles, seals, seabirds, sharks, and rays, but also large rorquals and sperm whales. Occasionally, they’ll even take a deer or moose that they catch as the latter are swimming across a channel. Within their family units, killer whales develop highly orchestrated hunting strategies that allow them to attack much larger prey, earning them the nickname of “sea wolf”. Group members cooperate to harass and herd their prey like a pack of wolves or a pride of lions. They dislodge seals from their ice floes and even beach themselves to capture some of their prey. These hunting strategies are transferred from adults to the young through learning. Depending on the location, killer whales are either very specialized, feeding exclusively on salmon or marine mammals for example, or highly adaptable to the type of prey available.

On the surface

The killer whale is a rather fast and energetic swimmer, and can reach speeds of 45 km/h when chasing prey. Like all dolphins, it is capable of aerial behaviours and exuberant leaps: it porpoises and surfs on the waves, can leap and lift its body entirely out of the water (full breach) to land on its back or belly, slaps the water surface with its tail and fins, spyhops by holding its head above the water and its body straight down to the pectoral fins, and can even swim backwards.

Diving

The diving behaviour and abilities of the killer whale are poorly documented. Most of its dives seem to be within 20 m of the surface, although they may exceed 100 m. Dive times are rather short (between 4 and 10 minutes) but can reach up to 20 minutes.

Social

Killer whales can be observed alone or in groups. For killer whales inhabiting the North Atlantic, little is known due to their low numbers, dispersion and nomadic ways. In the Pacific, which supports a resident population of some 300 individuals, killer whales live in stable matriarchal units that can comprise 2 to 3 dozen individuals.

Vocalization

From a vocalization perspective, the killer whale is very active. Its repertoire is vast: squeals, whistles, grunts, cries and clicks for echolocation. Each family unit has its own dialect, which is used for communication between members and for group cohesion.

Sexual maturity is reached between 12 and 16 years for females and between 10 and 17 years for males. Reproduction takes place year round with peaks in the spring and fall. Gestation lasts between 15 and 18 months. Though newborns begin to feed on solid prey quite early, they continue to suckle their mother until 1 year of age and are not completely weaned until the age of 2.