Length: 1.4 – 1.6 m (4.7-5.6’)
Weight: 61 – 76 kg (130 – 170 lbs)
Population size in Canada: Unknown
Population size in World: Unknown
Conservation status in Canada: Special concern (COSEWIC); under consideration for listing under SARA
Conservation status in World: Vulnerable   (IUCN)

Classification

Latin Name: Phocoena phocoena
Other Names: Common porpoise, Puffing pig
Suborder: Odontocete (Toothed Whale)
Family: Phocoenidae (porpoises)

Field Identification:
  • up to 5.6 feet in length
  • very small, with round, robust body
  • small, round beakless head
  • one blowhole
  • short, triangular, wide-based dorsal fin positioned in centre of body
  • body dark brown or grey on back, white on belly
  • dark stripe from corner of mouth to flipper
  • teeth peg-like and flattened sideways
  • difficult to see at sea due to short surfacing period
  • blow rarely seen, but sometimes heard
  • extremely inconspicuous, avoids vessels
  • acrobatics uncommon
  • group size 2-5 (1-12)
Description

The harbour porpoise is one of the smallest cetaceans, with a robust body and a short, poorly demarcated beak. The dorsal fin is triangular and medium-sized with small, blunt spines called tubercles on its leading edge. Not visible or appreciated from above the water, the colouration pattern of the harbour porpoise is quite complex. Its back is dark grey and its sides are lighter grey with variable dark grey flecking. The throat and belly are white, with some grey streaking on the throat and a dark chin patch, dark eye ring and a dark strip from the corner of the mouth to the flipper.

Life History

Harbour porpoises live life in the fast lane. Females reach maturity at about 3 years of age and give birth to a calf every year afterwards.  Gestation lasts 11 months and the female often becomes pregnant with the following year’s calf during this time. Hence, they are often simultaneously lactating and pregnant. Average life expectancy is around 24 years.

Distribution

Just like their name implies, harbour porpoises are a coastal species, found in bays, estuaries and harbours in temperate and subarctic waters of the Northern Hemisphere.  The North Pacific and North Atlantic populations are entirely separate. In the western North Atlantic, they are found from Cape Hatteras to West Greenland, including the Gulf of St. Lawrence. They are found around Iceland and the Faeroe Islands and from western Africa to the Barents Sea in the eastern North Atlantic. In the North Pacific, they occur from Monterey Bay and central Japan, north to the Chukchi Sea (including the Aleutian chain and northern Sea of Japan).  In the western North Atlantic, harbour porpoises arrive in the Bay of Fundy in July and remain until about September.

Diet

Harbour porpoises generally feed on schooling fish such as herring, capelin, sprats, and silver hake. They also eat cephalopods (squid and octopus).

Behaviour

Harbour porpoises are typically shy; they are difficult to approach and do not show much curiosity towards boats. They are generally solitary or found in small groups (2-5 individuals) and have large home ranges (thousands of square miles).  Unlike many species of dolphins, harbour porpoises do not perform any aerial acrobatics, though they do occasionally “pop” out of the water, revealing a large portion of their backs.

Population size

Read (1999) gave the following population estimates for harbour porpoises: In the Eastern Pacific Ocean: Central California 4,120; Northern California 9,250; Oregon and Washington 26,175. In the Atlantic Ocean: Gulf of Maine 67,500; Skaggerak and Belt Seas 36,046; North Sea 279,367; Ireland and western UK 36,280.

Threats

As a result of their coastal habitat, incidental mortality in fisheries, particularly bottom-set gillnets are a concern throughout their range. Since 1991, the Grand Manan Whale and Seabird Research Station (GMWSRS) have worked with fishing weir operators to release harbour porpoises from their weirs without losing the trapped herring. Their success rate for releasing harbour porpoises over the last 12 years has consistently been around 94%. Pollution is also of concern, particularly in the North and Baltic Seas.

References

CMS website: http://www.cms.int/reports/small_cetaceans/index.htm

Klinowska, M.  1991   Dolphins, Porpoises and Whales of the World. The IUCN Red Data Book.  IUCN, Gland, Switzerland. 429 pp.

Martin, Anthony R. and International Team of Experts. 1990. The Illustrated Encyclopedia of Whales and Dolphins. Portland House, New York, NY.

Read A.J. 1999. Harbour porpoise – Phocoena phocoena (Linnaeus, 1758). In: Handbook of Marine Mammals (Ridgway SH, Harrison SR Eds.) Vol. 6: The second book of dolphins and porpoises. pp. 323 – 356.

Reeves, P.A., R.R. Reeves, B.S. Stewart, P.J. Clapham, and J.A. Powell. 2002. Guide to the Marine Mammals of the World. Alfred A. Knopf, New York. 527 pp.