Harbour porpoise

What do harbour porpoise look like?

Harbour porpoises are relatively small compared to other dolphins. They have small, rounded heads with no beak and dark lips and chin. Equipped with robust, stocky bodies, they have predominantly dark brown backs with a pale grey or white underside, blending half way up their sides. A small triangular fin set just past the centre of the back is one of its very distinctive features.

Four subspecies of harbour porpoise are recognised: P. p. phocoena in the North Atlantic; P. p. vomerina in the eastern North Pacific; P. p. relicta in the Black Sea; and an unnamed subspecies in the western North Pacific.

What’s life like for a harbour porpoise?

Life for a harbour porpoise is by all accounts pretty fast and furious. They mature at an earlier age, reproduce more frequently and have a shorter lifespan compared to other toothed cetaceans (the collective name for all whales, dolphins and porpoises). Not only that but living with a high metabolic rate in cooler waters means that they need to feed continuously both day and night to provide the energy needed to survive. Each day, harbour porpoises will eat enough fish to replenish as much as 10% of their own body weight.

Mostly seen on their own, harbour porpoises are sometimes found in small groups. The most common social grouping is that of mum and baby.

What do harbour porpoises eat?

Ideally, harbour porpoises like to eat small schooling fish, like herring, sprat and sand eels – and lots of them, too. Squid and octopus are also favourites and appear on the menu when chance provides.

Where do harbour porpoises live?

Harbour porpoises are found in coastal waters of the sub-Arctic and predominantly cool temperate waters of the North Atlantic and North Pacific, although they are also found off the north west coast of Africa. They frequently visit shallow bays, estuaries, tidal channels less than 200m in depth and have also been known to swim up rivers. The majority of sightings occur within 10km of land and, although there is some evidence of north-south migrations, most harbour porpoise appear to have preferred habitat encompassing a broad area.