Fin Whale

In the St. Lawrence

Between May and late November, it is a seasonal resident of the Estuary and Gulf, where it comes to feed. Fin whales congregate in regions where food is abundant due to various oceanographic phenomena (thermal fronts, topography and upwellings), notably at the head of the Laurentian Channel (between Tadoussac and Les Bergeronnes). The population of the Gulf (excluding the Estuary) was estimated at 380 individuals (per aerial surveys conducted by Fisheries and Oceans Canada in 1995 and 1996, which did not account for animals below the surface).

Migration

Migratory movements and wintering grounds are poorly known. For reproduction, fin whales seem to migrate short distances toward the lower latitudes of the North Atlantic, without ever forming large pods.

In the world

Fin whales of the St. Lawrence are part of the North Atlantic population, whose numbers are not clearly known, with estimates having been made difficult by the expanse of its range and the risks of confusion with the sei whale. Nevertheless, a compilation of estimates suggests that the population of the North Atlantic may be as high as 56,000 individuals. One study demonstrated the genetic distinctions between fin whales of the Northwest Atlantic, Northeast Atlantic, and the Mediterranean. The species is present in all of the world’s oceans, from temperate waters to polar latitudes.

The fin whale was designated a “special concern” species by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 1987. Whaling, which ended in 1972, had taken a considerable toll on the number of fin whales on the Canadian East Coast and particularly on the Scotian Shelf. The lack of knowledge on this species justifies the status proposed.

The International Union for Conservation of Nature (IUCN) has listed the species as “vulnerable”. In the United States, the fin whale is considered “endangered” under the Endangered Species Act, and appears in the List of threatened or vulnerable species in Quebec under the Act Respecting Threatened or Vulnerable Species.

Feeding

The fin whale is a gulper, with a varied diet composed of planktonic crustaceans and small schooling fish (herring, capelin). It sometimes surface feeds where it performs circular or semi-circular manoeuvres, rolling its body onto its side (often the right side). Indeed, it is the only cetacean and one of the few vertebrates to exhibit an asymmetrical colour pattern on its head. On the right side, the lower jaw, oral cavity, tongue and throat are lighter in colour, bordering on white. Thus, the fin whale is believed to play with this contrast and light, either to frighten and herd its prey, or to better camouflage itself. One detailed study on fin whale behaviour compared to that of other rorqual species with no asymmetry did not allow either of these assumptions to be corroborated. This asymmetry might constitute an original trait of the fin whale, not offering any benefit in particular.

On the surface

Breathing sequences can comprise 5 to 10 blows. When a fin whale breaches – which is rare – its body lands on its belly or flank with a loud splash. It generally doesn’t show its tail when diving, a flexion movement of its supple body being sufficient to nosedive to the ocean depths.

Diving

The fin whale shows a marked preference for shallow coastal waters (100-200 m deep) and rugged seabeds. It dives to various depths (from just below the surface to up to 230 m), with patterns linked to various activities (diurnal and nocturnal, travel, rest, exploration, feeding).

Social

They are observed alone, in pairs or in temporary groups the size of which varies from 3 to over 20 individuals. The presence of food and tidal cycles influence their dispersion and grouping. A detailed study conducted from 1994 to 1996 on their behaviour in the Estuary showed that they formed tight groups at high tide in the tide rips, swimming in a synchronized and dynamic manner. At low tide, they were rather dispersed and relaxed.

Vocalization

The sounds emitted by fin whales are in the low-frequency range (below 120 Hz). Their repertoire is dominated by short pulsing sounds of decreasing frequency (23 Hz to 18 Hz), singular or emitted in sequence. Produced primarily in winter, these sequences may be used for mating rituals. The highest-frequency sounds seem to be used for short-distance communication. According to one study, very low-frequency pulsing sounds appear to be used for echolocation as well.

Males reach sexual maturity between 8 and 12 years of age and females, between the ages of 6 and 10. Mating takes place between December and January. Gestation lasts between 11 and 12 months. Calves are born between November and January. Nursing lasts 6 to 7 months. Newborns measure on average 6.4 m and weigh 1.9 t. Females can give birth every 3 years.