Marine Mammal Stranding Database

Marine Mammal Species Description

Harbor Porpoise

Phocoena phocoena

(Linnaeus, 1758)


Order: Cetacea
Family: Phocoenidae
Alternate Common Names: Common porpoise; puffing pig

Status: protected under MMPA


   Length: 4.6-5 ft (1.4-1.6 m)
   Weight: 110-132 lbs (50-60 kg)

Male harbor porpoises tend to be slightly smaller than females. Harbor porpoises have a pair of flippers near the head. The snout is rounded and has no noticeable beak. They have a small round body shape that helps them conserve body heat in colder habitats. Harbor porpoises also have a dorsal fin that is small and triangular-shaped. Its fluke or tail fin has a notch in the middle. Harbor porpoises have spade-shaped teeth. They are dark gray or brown on top of their body and fluke, with lighter sides and white on the belly with a dark stripe that extends from their eye to the flipper.


Harbor porpoises are most often seen in coastal waters less than 330 ft (100 m) deep typically in small groups (1-8 individuals). Mother-calf pairs are commonly seen. If food is abundant in an area, larger groups of up to 100 individuals are occasionally seen.


Harbor porpoises move around to find food. Their diet includes pelagic schooling fish species like herring, mackerel, capelin and alewife, other fish species and cephalopods (small squids). In waters less than 660 ft (200 m) depth, harbor porpoises forage on the bottom and in deeper waters they usually forage nearer the surface. Harbor porpoises can dive down to depths of 722 ft (220 m) for about a minute at a time.


Adult harbor porpoises reach sexual maturity at 3-4 years. Breeding season typically occurs from July and August. The gestation period lasts approximately 11 months and most calves are born from May to August. After birth, calves are nursed for about a year but start feeding on their own in four to five months. Females usually have young every two years.


The average life expectancy for harbor porpoises is eight to ten years, with a maximum recorded life span of 23 years.

Distribution / Range:

Harbor porpoises occur in the temperate and sub-polar regions Northern Hemisphere. In the United States, they occur primarily in the northern states south to mid-California in the Pacific and south to the Carolinas in the Atlantic. Individuals have been documented as far south as Florida in the Atlantic.

Similar species:

The harbor porpoise is the only porpoise occurring in the southeastern United States. One way to tell dolphins from porpoises is that porpoises have spade-shaped teeth and dolphins have conical-shaped teeth. The Atlantic White-sided Dolphin (Lagenorhynchus acutus) has a small beak and a falcate dorsal fin that helps distinguish it from the harbor porpoise that lacks a beak and has a small triangular dorsal fin. Harbor porpoises can be distinguished from dolphins in the genus Stenella, short-beaked common dolphins (Delphinus delphis), Atlantic bottlenose dolphins (Tursiops truncates), and rough-toothed dolphins (Steno bredanensis), by lacking the distinctive elongated beak of any of these species.



American Cetacean Society. 2006. American Cetacean Society Fact Sheet. Accessed January 2012.

Bjørge, A. and K.A. Tolley. 2009. Harbor Porpoise - Phocoena phocoena. In: Encyclopedia of Marine Mammals 2nd Ed. Perrin W.F., B. Würsig, and J.G.M. Thewissen, eds. Academic Press, New York, pp. 530-533.

Gaskin, D.E. 1999. Harbor porpoise, Phocoena phocoena. In The Smithsonian Book of North American Mammals. Wilson, D.E. and S. Ruff, eds., 295-296. Smithsonian Institution in association with the American Society of Mammologists, Washington DC.

Hammond, P.S., Bearzi, G., Bjørge, A., Forney, K., Karczmarski, L., Kasuya, T., Perrin, W.F., Scott, M.D., Wang, J.Y., Wells, R.S. & Wilson, B. 2008. Phocoena phocoena. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. Downloaded on 09 January 2012.