Species: Harbour Porpoise – Phocoena phocoena
B.C. Status: Blue
COSEWIC Status: Special Concern
Harbour porpoises are shy creatures that may be hard to spot despite living in coastal areas such as estuaries, inlets, bays, fjords and, of course, harbours. They are British Columbia’s smallest cetacean, belonging to the same classification order as whales and dolphins. However, while dolphins will sometimes get close to boats and even surf the bow wave, harbour porpoises prefer to stay out of sight.
They tend to keep their surface activity minimal. Look for a glimpse of a dark blunt head and a medium-sized triangular dorsal fin. The average length of an adult is 1.6 metres, and females are slightly larger than males. Their lifespan in the wild is documented variably between 8 and 24 years of age, though most animals live to about 13.
Harbour porpoises often hunt solo or in small groups of two to five individuals. In the spring and autumn, when seasonal tides bring concentrated prey, the porpoises may congregate in larger numbers – usually several dozen, with a recorded sighting of 200. Their preferred food is small schooling fish such as herring, and they also feed on squid. Newly-weaned calves may supplement their diet with small shrimp-like crustaceans such as krill (euphausiids) in the transition to adulthood. Porpoises catch prey with their spade-shaped teeth and swallow it whole. Like other cetaceans, they use echolocation when hunting in low-visibility conditions. (Check out the “Useful Links” below, for an article describing this specialized evolutionary trait). Although they prefer shallow waters, they will occasionally dive to a depth of up to 200 metres.
Mating for these animals reaches its peak in late summer to early fall in B.C. Females are thought to mature at three to four years of age and bear a calf every one to two years. Their pregnancies average ten months, and a calf stays with its mother to nurse for the first eight months of its life.
The harbour porpoise has been quite adversely affected by human activity and is now rarely seen in busy marine coastal areas such as Haro Strait, near Victoria. Worldwide, it is estimated that each year, many thousands of harbour porpoises succumb to entanglement in fishing traps, especially gillnets. These sensitive animals are also negatively impacted by pollution that leads to environmental contamination and thus, accumulates in their tissues. They are also affected by underwater noise pollution, which can interfere with their communication and navigation. Encroachment on their prime habitat, with development and boat traffic, has also resulted in declining numbers of harbour porpoises. Furthermore, they are the most frequently reported stranded cetacean in B.C. Though the reasons for the strandings vary, it may be partially explained by the porpoises’ choice of living in close proximity to land.
A recent call for global action signed in early October 2020 by 350 scientists from 40 countries warns that more than half of the 90 species of whales, dolphins and porpoises alive today are at risk. While the United Nations is negotiating a Global Oceans Treaty that proposes to create marine sanctuaries in international waters by 2030, coastal-dwelling species, such as the harbour porpoise, require individual nations to take action on their behalf. The Canadian government reports that it has many ongoing and planned actions, from research to policy amendments, that focus on protecting these creatures from the multiple threats they currently face. The harbour porpoise is a species of special concern.
Identification – what to look for:
- Small, stocky, tapered body with a rounded head (unlike the prominent forehead and snout of dolphins)
- Adults are around 1.6 metres in length
- Dark brown to dark gray on back, fading to lighter gray on the sides and white on the belly, (calves are usually darker than adults).
- Dark stripe from the corner of the mouth to the pectoral flipper
- Triangular dorsal fin, the same colour as the body
- Small curved flukes and a middle notch on the tail
- Body does not fully breach the surface of the water
Where are they found?
- Throughout temperate and subarctic coastal waters of the northern hemisphere
- Northwest and Northeast coast of North America, West coast of Europe down to Northwest coast of Africa, East coast of Asia
- Typically stay in shallow waters less than 150 metres
- Harbour porpoises have been spotted hundreds of kilometres inland in rivers, a rarity for marine mammals.
- Females can be simultaneously pregnant and lactating.
- In British Columbia, male harbour porpoises will sometimes mate with female Dall’s porpoises.
- The males experience a pronounced development of their testes during the mating season, which can enlarge to 6% of their total body weight.
- The word “porpoise” originates from “porcopiscus,” its Latin precursor in the Middle Ages period, which was a combination of the words “pig” and “fish.” One nickname for porpoises is “puffing pigs” due to the loud exhale they make when surfacing for air.
- Difference between a Dolphin and Porpoise
- Video of Curious Harbour Porpoise
- Article about Harbour Porpoise calls and echolocation
- The Secret Life of Harbour Porpoises | WildWhales
- SARA Harbour Porpoise
- UN Treaty to Protect World’s Oceans
- Hakai Magazine
- Ocean Wise, Vancouver Aquarium
- Porpoise Conservation Society
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