Sperm whale | Physeter macrocephalus

Tracks

The blow is low and bushy, one and a half to five metres high, and angled forwards and to the left; in calm weather this can be seen from far away. Between dives the animal lies almost motionless at the surface for several minutes ('logging'), with only head and back showing, breathing regularly. Before the next dive it arches its back, so that the hump and knuckles break the surface one after the other, and raises the broad, triangular flukes high out of the water. A dive usually lasts 25 to 50 minutes and goes to 400 to 600 metres; dives to 3,200 metres and of up to two hours have been recorded. Females and young live in family units of about ten adult females with their young; adult males in the north are usually alone. With a hydrophone you can hear the clicks with which Sperm Whales search for prey and keep contact underwater; whale-watching boats use them to find the animals.

Identification

A dark, grey-brown whale with an enormous, rectangular head, which ends bluntly like a block in profile and can take up to a third of the body length. The skin behind the head is wrinkled, like a crumpled sheet. There is no true dorsal fin: about two thirds of the way along the back sits a low, thick, rounded hump, followed by a row of smaller knuckles towards the tail. The single blowhole lies at the front left of the head. The lower jaw is narrow and set below the head; it carries teeth, the upper jaw does not. The flukes are broad, triangular and deeply notched, with a straight trailing edge and a dark underside. Males reach 19.2 metres, females 12.5 metres.

Similar species

The blow alone identifies the Sperm Whale: angled forwards and to the left, whereas the blow of all the other large whales of the guide area rises vertically. The Humpback Whale also raises its flukes before a deep dive, but they have a wavy trailing edge and a white or black-and-white underside, and the humpback has long white flippers and a fin on a hump. The large rorquals have a smooth, streamlined back with a distinct dorsal fin and rarely show the flukes on diving. A Sperm Whale lying still at the surface can look like a floating log at long range.

Habitat

Deep water, above all beyond the continental shelf, along its slope and over submarine canyons and troughs, mostly where the sea is deeper than a thousand metres. The diet consists mainly of deep-sea squid of many species, supplemented with fish. Where a deep canyon lies close to the coast, as the Bleik Canyon (Bleiksdjupet) off Andenes or the canyons of the Bay of Biscay, the species comes close to land.

Distribution

Worldwide in the deep oceans. In the guide area mainly beyond the continental shelf, along the Mid-Atlantic Ridge and around the oceanic islands: off the Azores and Madeira family groups live all year. Males move north, to beyond Norway; off Andenes in Vesterålen they are seen year-round in the Bleik Canyon (Bleiksdjupet). Further in the Faroe-Shetland Channel, the Rockall Trough and along the shelf edge west of Ireland, and in the deep canyons of the Bay of Biscay. The Mediterranean holds a separate subpopulation, with concentrations in the Hellenic Trench off the Greek coast, around the Balearics, in the Ligurian and Tyrrhenian Seas and in the Strait of Gibraltar. The species does not belong in the shallow North Sea; males that stray there on their way to or from the north usually strand between November and March.

• Native
• dark = core range, pale = thinly spread

Way of life

Active by day and night; the animals hunt in the darkness of the deep sea and rest at the surface between foraging dives, sometimes hanging vertically. Females stay in a family group for life and look after the young together; the calves stay near the surface while the mothers dive. Young males leave the group, first form groups of animals of the same age and, as they grow older, move further and further north; adult males return to the warmer waters of the females to mate. Gestation is fourteen to sixteen months and a female calves once every three to fifteen years. A newborn calf is 3.5 to 4.5 metres long and weighs about a thousand kilos.

Where and when to look

From Andenes in Vesterålen boats go out all year to the Bleik Canyon, where males feed a short distance off the coast; most trips run in summer. In the Azores (mainly from Lajes do Pico and Ponta Delgada) and in Madeira females with young can be seen. In the Mediterranean the chances are best in the Strait of Gibraltar from Tarifa, in the Ligurian Sea and in the Greek waters of the Hellenic Trench. In calm seas look for a low, slanting blow and a dark, motionless back at the surface; an animal that raises its flukes is gone for half an hour or more.

Conservation status

Vulnerable (VU, 2019). The Sperm Whale was hunted for centuries for its oil and the spermaceti in its head, and has been protected since the moratorium on commercial whaling of the 1980s. The Mediterranean subpopulation is listed as Endangered (EN) and is estimated at 250 to 2,500 mature animals; threats there are illegal driftnets, ship strikes and underwater noise. In January and February 2016 about thirty Sperm Whales, all young males, stranded along the North Sea coast; large amounts of marine debris, including net remains and plastic, were found in the stomachs of some of them. The species is listed on Annex IV of the Habitats Directive and is covered by ACCOBAMS and ASCOBANS.

Scientific name

Physeter macrocephalus | Linnaeus, 1758

Linnaeus described the species in 1758 and placed it straight away in the genus where it still stands. Physeter is Greek physētēr, 'blowpipe, blowhole of a whale', from physaō, 'to blow'. macrocephalus is Latinised Greek makrokephalos, from makros, 'large', and kephalē, 'head': big-headed.