Small in size and relatively shy by nature, these porpoises live in coastal waters, often frequenting bays and sometimes swimming up the mouths of rivers. Living close to the shore can be hazardous for these porpoises, as they may be caught in fishing nets, with fatal consequences. This has led to a major decline in their populations in the Baltic and Black seas.
Harbour porpoises are relatively common in European waters and along the coast of North Africa, where they occupy shallow coastal waters. They are also able to withstand fresh water and often travel in the mouths of large rivers.
These porpoises, also known as common porpoises, are social, highly vocal cetaceans. They are usually seen in small groups comprising up to 10 individuals, increasing the likelihood of finding sufficient food. Harbor porpoises swim more slowly than dolphins and rarely jump out of the water. Instead they rise to the surface to breathe. Some groups migrate long distances, but most occupy a territory.
Unlike their dolphin relatives, porpoises have blunt snouts without a beak. They also have fewer teeth, which tend to be less pointed and have a chisel-like biting edge. These teeth are suited to holding on to large struggling fish.
Harbour porpoises eat fish, such as herrings, sardines and pollack. Each porpoise must eat up to 10 per cent of its body weight daily. They also eat squid and shrimp. Like other cetaceans, they use high-pitched clicking sounds to echolocate their prey. Many of the porpoise’s prey are also commercially important species, and porpoises are sometimes caught up in fishing nets.
Distribution: Occurs in northern coastal areas on both sides of the Pacific and Atlantic oceans, to southern Greenland and also western Africa. Also present in the Black Sea.
Habitat: Shallow seas and coastal waters. Sometimes venture into estuaries.
Weight: 60 - 90 kg (130 - 200 lb); females are slightly larger.
Length: 1.5 - 1.8 m (5 - 6 ft).
Maturity: 3 - 4 years.
Gestation Period: Around 341 days; calves are about 71 cm (27 in) long at birth.
Breeding: 1; weaning takes about 8 months.
Food: Piscivorous, hunting smaller fish such as whiting, herring, pollock and sardines, as well as squid.
Lifespan: 10 - 20 years, typically shorter than most other cetaceans.
This is triangular in shape, and quite low, yet with a broad base.
Dark on the upperparts, with a whitish underside.
These are small, rounded and dark in colour, with a dark stripe extending forwards towards the eyes.
The head is rounded, with no evident beak; the teeth are quite small in the jaws.
The young porpoise is born tail-first, and then helped up to the surface by its mother, so that it can obtain air.
Harbour porpoises may be hunted by killer whales.