Harbour porpoise
Phocoena phocoena

Nicknamed the ‘puffing pig’ in eastern Canada, the harbour porpoise is British Columbia’s smallest cetacean. Living in the same waters as the well-known killer whale and the lively Dall’s porpoise, the harbour porpoise is often overlooked.

Description

It is quite likely that B.C. boaters pass near many harbour porpoises without even knowing they’re there. That’s because the harbour porpoise blends in very well with its marine environment. It is dark brown or gray in colour on its back, paler on its belly. Its body is chunky, with a small head, tiny flippers and a low, triangular dorsal fin. Its mouthline is short and straight, tilting slightly upwards. Like all porpoises, it does not have much of a snout, or beak. Fully grown, harbour porpoises are about 1.8 metres long and weigh about 90 kilograms.

Range

Harbour porpoises are found in the colder oceans of the northern hemisphere. They are common year-round in coastal areas between central California and southern Alaska. As their name suggests, they are often seen in shallow inshore waters such as bays, river mouths, and harbours.

Behaviour

Appearance is not the only reason harbour porpoises are hard to see. They are shy and normally try to avoid boats. They almost never ride the bow waves of boats and rarely, if ever, leap out of the water. They can swim at speeds of up to 20 km/h, but usually they travel quite slowly. On rough days they are almost impossible to spot. In calmer waters, the only signs they are there are their small dorsal fins and the sharp puffing sound of their breath. While it does not sound like a kind nickname, ‘puffing pig’ is an affectionate way to describe their travelling style.

Harbour porpoises are usually seen alone or in pairs. Occasionally, they may gather in groups of up to 20, but this is rare. In B.C., most calves are born between May and September. They are about 90 centimetres long at birth and likely stay with their mothers for at least six months.

The harbour porpoise eats squid and a wide variety of small fish, such as herring. It uses its small, spade-shaped teeth to capture its prey, which it usually swallows whole.

Status

Although the world population of harbour porpoises is unknown, their numbers are declining in some regions. They are listed as endangered in eastern Canada. There is concern that their numbers are also falling in B.C. but it is not known how many there are.

Because they prefer shallow coastal areas, harbour porpoises may be particularly sensitive to human activity. They sometimes become entangled in fishing nets and drown. Others may be driven out of their normal range by heavy boat traffic. And because harbour porpoises are high in the coastal food chain, their tissues can store high amounts of dangerous pollutants such as PCBs and DDT.