Length: 6 – 9m (19-30’)
Weight: 6 – 8 tons
Population size in Canada: Scotian Shelf ~160, Labrador population – unknown
Population size in World: estimates between 10,000 – 40,000 in North Atlantic
Conservation status in Canada: Endangered (COSEWIC/SARA)
Conservation status in World: Lower Risk: conservation dependent (IUCN)

Classification

Latin Name: Hyperoodon ampullatus
Other Names: North Atlantic Bottlenosed whale, Bottlehead, Steephead
Suborder: Odontocete (Toothed Whale)
Family: Ziphiidae

Field Identification
  • medium size
  • robust cylindrical body
  • large, rounded or squared-off head
  • head of mature male is square, white and often scarred
  • dolphin-like beak
  • tall curved dorsal fin located two-thirds down back
  • flippers small & dark
  • dark grey to brown colour, may lighten with age
Description

Northern bottlenose whales are the third largest beaked whale species. Adult females reach lengths of up to 29 feet and adult males, lengths of up to 32 feet. They are recognizable by their long and tube-like beak which is distinct from their prominent melon. The dorsal fin is small and curved, located approximately two-thirds down the back. Their flippers are small and rounded. Flipper pockets are located on the sides of the body and allow the flippers to be laid flat against the body surface.

The forehead bone of males becomes larger and heavier as they age which leads to a change in the shape of the forehead. Adult males have a large, flat, squared-off forehead whereas females and immature males have a smoother, rounded forehead. This distinction allows adult males to be identified when out to sea.

Life History

Females reach sexual maturity at 8-12 years old and the oldest recorded female from whaling data was 27 years old. Males mature around 9-11 years old, with the oldest whaled male being 37 years old. Ages provided by whaling data are likely to be underestimates as the technique of aging by counting dentine layers in teeth becomes more inaccurate with older animals of some species as the later layers are not very distinct. Gestation is estimated to be 12 months with calves being born in late spring and summer. Calves may be born slightly later in the Gully. Females are believed to have calves every two years and lactation lasts for one year.

Distribution

Northern bottlenose whales are found only in the North Atlantic; from the ice edge to the Azores. Population centres are found off Iceland, Norway, the Davis Strait/northern Labrador and Nova Scotia. They are typically found in waters deeper than 500m and concentrate in submarine canyons, the shelf edge and other areas of high relief.

A small, resident population is found in the Sable Gully, a submarine canyon located approximately 200 km southeast of Nova Scotia. It is likely that the bottlenose whales on the Scotian Shelf are largely or totally distinct from the Labrador population. This suggestion is based on results of population models, differences in breeding season and differences in the average length of adult whales in Labrador and the Gully (whales in Labrador tend to be larger on average). There may be reproductive isolation between these two populations.

Diet

The deep diving capability of the northern bottlenose whales allows them to feed on the bottom in very deep water. They feed predominantly on squid of the genus Gonatus although other species of squid and fish are occasionally consumed.

Behaviour

Northern bottlenose whales are among the deepest diving marine mammals with regular recorded dives up to 800m and a maximum depth of over 1400m; these dives were routinely to or near the sea floor.

Groups typically consist of between 3-10 animals. Mixed groups of different age-sex classes are commonly observed, although there is some suggestion that smaller groups (<4) are often composed of individuals of similar age and sex.

Population size

The population size of northern bottlenose whales is poorly known throughout most of its range. A study in 1992 estimated that there were approximately 44,000 bottlenose whales around Iceland, however, this is likely an overestimate. No current estimates exist for the Davis Strait. However, numerous opportunistic sightings made in this area in the late 1970’s which could indicate that they are relatively common in this area. Recent work conducted off Labrador yielded very few bottlenose whale sightings suggesting that the population in this area could be lower than previously thought.

Only in the Gully has there been extensive work to estimate the population size. The population is estimated to contain approximately 160 individuals.

Threats

The commercial hunt for bottlenose whales began in the 1850s and lasted until the 1970s. Over 80,000 whales were taken during this time. Eighty-seven of these were captured from the Gully in the 1960s.

Like other marine mammals, northern bottlenose whales are threatened by a number of human activities including fishing, shipping and chemical and noise pollution. The increase in the human activities (particularly hydrocarbon exploration) on the Scotian Shelf has caused concern for this population to increase and in 2002; this population was uplisted by COSEWIC to the Endangered category. In 2006 it was officially added to the Canadian Species at Risk Act.