Northern Bottlenose Whale – Hyperoodon ampullatus
Habitat: Primarily in waters >500 m, may be associated with submarine canyons.
Description: Largest British beaked whale, distinguished by other beaked whales by large, bulbous forehead and short dolphin-like beak. Body is long, robust, cylindrical. Colour very variable, from chocolate brown to yellowish brown above, lighter on flanks and belly, irregular pathes or blotches; male forehead becomes lighter with age. Newborn calves are grey with dark eye-patches and light heads. Older males have single pair of conical teeth, up to 41mm, erupting at tip of lower jaw; in females, these rarely appear through gum. Second pair may be buried in gums behind first, vestigial teeth may be embedded in both upper and lower jaws. Pair of v-shaped throat grooves. Single cresent-shaped blowhole in depression behind forehead. Flukes are broad and un-notched, dorsal fin is curved, 30 cm, 2/3 along back.
Size: Males 9 – 9.5 m, females 7 – 8 m.
Lifespan: At least 37 years, probably much more.
Distribution: Temperate and arctic north Atlantic, from ice-edge to Azores, prefers deep waters. Main regions of concentration appear to be west of Norway, west of Spitsbergen, north of Iceland, Davis Strait off Labrador, Faroes, east Canada. Majority of sightings and strandings occur on all British and Irish coasts, majority in July – September.
Diet & Feeding: Mainly feeds on adult squid Gonatus (in UK, probably G. fabricii). Other squid and fish including herring and redfish occasionally eaten. Appears to forage largely at or near the sea floor.
Breeding: Gives birth in late spring – summer. Gestation period >12 months; lactation period uncertain but >12 months; calving interval at least 2 – 3 years. Sexual maturity reached at 7 – 11 years in males, around 11 years in females. Mating system unknown; males may be territorial.
Conservation Status & Population: Listed by IUCN as lower risk but conservation dependent. No detailed population estimated for North Atlantic but surveys in late 80s suggested 40,000. Locally abundant, but overall population surely heavily depleted by whaling.PCB and DDT levels similar to other cetaceans, relatively high levels of cadmium in liver. Oil and gas development off Hebrides and in north North Sea may present acoustic and contaminant threats and, like other beaked whales, may be susceptible to trauma induced by mid-frequency active sonar and other loud sound sources. Ship collisions occur. No commercial whale-watching due to offshore distribution.
Previously hunted for oil and animal food. Scottish and Norwegian whalers took, in total, 60,000 throughout N Atlantic from 1850 – 1920. Since then, yearly catches are much reduced.
Large bulbous head and short bottle-nosed beak. Teeth in male are distinctive but rarely visible in live animal. Will often approach vessels. Stays at surface for >10 minutes after long dives, blowing regularly. Rarely shows tail flukes at onset of dive. Blow is low (<2 m), bushy, slightly forward-pointing. Flippers are short, can fold into indentation in body. Usually seen in groups of up to 4, occasionally up to 14.
Vocalisations: High frequency echolocation clicks (24 kHz). One encounter recorded whistles (3 – 16 kHz) and chirps (3 – 16 kHz) lasting 115 – 850 ms but this may have been confounded by pilot whales; a more detailed study did not record such sounds.