Harbour Porpoise

Marine Creature:  Harbour porpoise (Phocoena phocoena)
Kindly compiled by Gemma Cave & Olivia Harries of The Hebridean Whale and Dolphin Trust

Harbour posrpoise at surface showing characteristic triangular dorsal fin

Harbour posrpoise at surface showing characteristic triangular dorsal fin

General Description

The harbour porpoise is a small, inconspicuous species of cetacean found in coastal waters of the northern hemisphere. It is the smallest species found in the Scottish Hebrides. Harbour porpoises are small and rotund, with no beak, a small, triangular dorsal fin, and are dark grey with paler coloured bellies.


Harbour porpoise are found in coastal waters in the northern hemisphere, between about 10° to 70° N. They are a relatively common, and resident, species of the west coast of Scotland.

porpoise3Interesting Facts

They are sometimes known as ‘puffing pigs’ because of the noise they make when they surface. The Scottish Gaelic name for harbour porpoise is peileag. They are not considered to be a sociable species and are not thought to vocalise, but they do echolocate.

  • Food: Small schooling fish such as herring, sprat, sand eels, as well as some cephalopods.
  • Lifespan: Up to 24 years
  • Size: 1.4 – 1.7m long, 50 – 80 kg, females are slightly larger than males.

Reproduction:  Harbour porpoise are quite short-lived so, once females reach sexual maturity at about three years, they can then produce a calf each year for several years. Gestation lasts for up to 11 months, meaning females can be pregnant and lactate at the same time.

Feeding & Hunting:  Usually forage alone or in small groups, although larger cooperative feeding aggregations are sometimes seen.


Predators include large sharks and killer whales. In the Hebrides, there have been several accounts of killer whale hunting harbour porpoise. They are also susceptible to being disturbed or killed by many human activities. Because of their feeding habits, they are at a high risk of entanglement in fishing gear. It is believed that several thousand may be entangled and drowned each year in UK waters, primarily in gill nets. Harbour porpoise distribution overlaps with areas of the coast that are most heavily used by people, which means they are exposed to high levels of shipping traffic, coastal development and other human sources of disturbance. Hearing is the most important sense for porpoise, but the loud underwater noises caused by vessels, military activity and seal scarers (Acoustic Deterrent Devices) used by some fish farms may impact on their distribution and welfare. HWDT’s boat-based research programme aims to develop an understanding of the most important habitats and the key habitat requirements for harbour porpoise off the west coast of Scotland to help protect the species in the future.

Conservation Status & International Protection

The harbour porpoise is protected under UK and EU law, principally under Schedule 5 of the Wildlife and Countryside Act 1981, the Nature Conservation (Scotland) Act 2004 and by the 1992 EU Habitats and Species Directive. The populations in the Black and Baltic seas are thought to be the most threatened. Like other cetacean species, harbour porpoise are important indicators of overall ecosystem health.

porpoise 4How can people help?

By adopting environmentally responsible attitudes, we can all contribute to more sustainable uses of the marine environment. Simple lifestyle changes, such as recycling, using environmentally-friendly products and choosing responsibly sourced seafood, will help to improve the overall health of our oceans. If you encounter harbour porpoises at sea, be considerate in the way you approach them. They are elusive animals that usually steer clear of vessels, so enjoy them from a safe distance, and keep a constant speed and heading so as not to disturb them. If you see harbour porpoise off the west coast of Scotland, you can report your sighting to the Hebridean Whale and Dolphin Trust via the online sightings form at www.hwdt.org to contribute to a better understanding of this remarkable little cetacean.

Best places in the world to see these creatures:

Within their geographic range, look for harbour porpoise close to the coast and in bays, estuaries and harbours. Patience is required as they are elusive animals that can be hard to spot, as they surface only briefly to breathe and can be particularly tricky to see in rougher seas. In the UK, look for tour operators with the ‘WiSe scheme’ accreditation to ensure responsible wildlife-watching.  For ethical reviews and rating system for whale watching trips to see Harbour Porpoise visit www.planetwhale.com


Scientist Profile:  Olivia Harries, Biodiversity Officer


The Hebridean Whale & Dolphin Trust (HWDT)

porpoise 4

Year(s) Founded: 1994


Description/Background of work

The Hebridean Whale and Dolphin Trust (HWDT) is dedicated to enhancing knowledge and understanding of Scotland’s whales, dolphins and porpoises and the Hebridean marine environment through education, research and working within Hebridean communities as a basis for the lasting conservation of local species and habitats. Specifically, HWDT conducts long-term monitoring of cetacean abundance, distribution and habitat use, engages a wide range of people in marine environmental education through hands-on, outdoor learning experiences and provides local communities with volunteering and training opportunities to promote sustainable management of marine resources.

Importance of work

As the only long standing research organisation on the west coast of Scotland, HWDT’s projects are vital to the effective management of marine megafauna populations. Our research is at the centre of marine spatial planning, and the construction of aquaculture sites and renewable energy sources can depend on the results from our analyses.

Because of the high degree of behavioural and social flexibility that some species of cetaceans (mostly dolphins) have demonstrated throughout their range, it is essential to understand factors affecting local cetaceans, if their populations are to be managed and conserved. Information on habitat use also seems applicable to coastal management plans.

Websites: www.whaledolphintrust.co.uk / www.hwdt.org

porpoise2Funding bodies

The Hebridean Whale and Dolphin Trust is a small, locally-based charity reliant on income from supporters, donations and funding. HWDT is grateful to currently receive funding and support from: Awards for All Scotland, Earthwatch, Miller Philanthropy, Scottish Natural Heritage, The Bromley Trust, The Robertson Trust, WWF and a number of smaller bodies.

Surveys around St Kilda, Scotland

Surveys around St Kilda, Scotland

Volunteer /Paid Work Opportunities

HWDT advertise all paid and voluntary positions on the website www.hwdt.org. From May to September each year, paying volunteers assist with data collection onboard the research vessel Silurian. Details of these live-aboard trips can also be found on the HWDT website. There are many other opportunities for land-based volunteers so please contact HWDT to find out more.


 Return to Toothed Whales or learn more about the Common Bottlenose Dolphin