Granddad’s Camera
Harbour porpoise, as it appears in the game

No.064 · Mammals · Uncommon

Harbour porpoise

Phocoena phocoena

Britain's smallest cetacean: a shy, rotund little porpoise whose dark back and small triangular fin roll briefly at the surface.

When to look

April to October, mostly at dawn and day.

Time of day

Best time
Calm, clear days, best July–October, from a headland or boat.
Where in the game
the Pembrokeshire coast (sea)
Size
Usually 1.45–1.60 m; females larger, up to 1.90 m
Weight
Usually 50–55 kg; up to 81 kg. Calves are 6–10 kg at birth
Lifespan
Usually no more than 12 years, up to 24
Population
About 493,000 across the shelf seas from southern Norway to Portugal in summer 2016 (Sea Watch Foundation)
Status
Least Concern globally; Baltic population Critically Endangered (Sea Watch Foundation)

Diet

A varied diet of fish, squid and crustaceans, mainly from near the seabed: herring, sprat, sand eels, gobies and gadoids such as cod and whiting

Habitat

Shallow coastal shelf seas, often in tide races and sounds

Breeding

Calves are born May–August, peaking in June, after 10–11 months. Females breed every 1–2 years

Field signs

  • A small dark back and tiny triangular fin, gently rolling
  • No leaping and no bow-riding
  • A short, sharp puffing 'chuff' as it breathes
  • Often 1–3 animals, or a mother with a calf

Did you know?

  • Porpoises live fast and die young: 12 years is typical and a few reach 24.
  • The Irish Sea holds a significant concentration of harbour porpoises (Pembrokeshire Coast National Park).
  • Bycatch in bottom-set gill nets and pelagic trawls is the main threat (Sea Watch Foundation). Porpoises are usually alone or in ones and twos and, unlike dolphins, do not usually bow-ride.

Moments worth waiting for

  • Mother and calf June to August, day
    A small dark fin rises beside a bigger one: a mother porpoise with a calf stuck close to her side.

Photo tip

Wait for a calm day with the sun behind you and scan for the slow roll. Pre-focus on the last surfacing spot and shoot bursts with a 300 mm lens; you get a fraction of a second. Don't waste time chasing: patience works better.

Be a good naturalist

Watch from the shore or with a WiSe-accredited boat operator. Follow the Pembrokeshire Marine Code: be aware of animals at 100 m and keep at least 50 m away unless they approach you, slow to under 5 knots, hold a steady course, allow an escape route, never chase, and leave if animals show signs of disturbance. Report sightings to the Sea Watch Foundation.

The law

Legally protected in European, British and Irish waters (Sea Watch Foundation): all dolphins and porpoises are on Schedule 5 of the Wildlife and Countryside Act 1981, and it is an offence to deliberately disturb or harm one

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