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Phocoena phocoenaharbor porpoise

By Andrew Masi

Geographic Range

Found in coastal regions of the North Atlantic, Arctic, and North Pacific Oceans; also the Mediterranean and Black Sea regions. They are found in bays, estuaries, river mouths, and sometimes ascend further up rivers. (Dollinger (editor), 1988; Nowak, 1999; Dollinger (editor), 1988; Nowak, 1999)

Habitat

Found in both salt and fresh water areas, Phocoena phocoena require a shallow coastal body of water. In the Western Atlantic, they also move far out to sea near the end of summer and reappear in spring. Other regional populations move south or farther away from shore to avoid ice buildups. (Nowak, 1999)

Physical Description

Phocoena phocoena, also known as the "Common" or "Harbor" Porpoise, is a small cetacean that is 1.5 to 2 meters long and weighs from 45 - 65 kilograms. The female of the species is usually slightly larger than the male. The color of the animal varies from individual to individual, but the most common coloration pattern is a dark dorsal surface that shifts to a lighter colored hue ventrally. Although the dark color is usually black or deep gray, albinos have been reported in which the dark segments are completely or partially white. The flippers, dorsal fin, and tail are all dark in color, and there is a black stripe that runs from the edge of the mouth or eye to the flipper on either side. There is no noticeable forehead or beak on this species, and the snout is short, giving the head a somewhat cone-like shape. P. phocoena has two pectoral flippers, a single dorsal fin, and a tail with two partially separated flukes. All of these appendages are short and not very sharp, with the dorsal fin being triangular shaped and usually around 15 - 20 cm tall. There is a noticeable keel located near the all dark tail flukes, with the tail itself spanning anywhere from 30-65 cm. Inside the slightly upturned mouth there are rows of 16-28 spade-shaped teeth. There is no variance in the shape or type of teeth in P. phocoena. (Dollinger (editor), 1988; Nowak, 1999; The Porpoise Page, 1998)

  • Sexual Dimorphism
  • female larger
  • Range mass
    45 to 60 kg
    99.12 to 132.16 lb
  • Range length
    1.5 to 2 m
    4.92 to 6.56 ft
  • Average basal metabolic rate
    107.675 W
    AnAge

Reproduction

It is not clearly known how extensive the mating season is in P. phocoena, but it seems that mating mainly occurs from June to September with births occurring from May to August. It is commonly noted that gestation lasts 11 months with nursing following for another 7 or 8 months. A female will give birth to one calf per year, with the birth size of the calf being 6-8kg and 70-100cm long. Sexual maturity is reached by the fifth year, if not before, and the life span of P. phocoena is believed to be anywhere from 6 to 20 years. (Johnston(1999), Nowak(1999))

  • Breeding interval
    A female will give birth to one calf per year
  • Breeding season
    Mating mainly occurs from June to September
  • Average number of offspring
    1
  • Average number of offspring
    1
    AnAge
  • Average gestation period
    11 months
  • Average gestation period
    320 days
    AnAge
  • Range weaning age
    7 to 8 months
  • Range age at sexual or reproductive maturity (female)
    5 (high) years
  • Range age at sexual or reproductive maturity (male)
    5 (high) years

Lifespan/Longevity

Behavior

The species usually swims near the surface, rising to the surface to breath about every 25 seconds. It does not present a very playful attitude, ignoring boats and rarely jumping out of the water. Harbor Porpoises do not move particularly fast, but when pursued can reach speeds of around 23km/hr. When diving for food this porpoise stays down for an average of 4 minutes, and is believed to be able to dive as deep as 200m. Although schools of up to 100 individuals may sometimes be seen, P. phocoena is usually seen in pairs or in groups of 5-10. When the larger groups do occur, it is usually because a number of smaller groups have joined together while following a rich food source. Mothers bring newborn calves to secluded coves to nurse. Some populations are known to migrate, but when they return to their regular waters they are territorial, patrolling certain areas. (Johnston(1999), Nowak(1999))

Communication and Perception

Food Habits

Diet consists mainly of smooth, non-spiny fish, and cephalopods. Herring, pollack, hake, sardines, and cod are commonly eaten. Other sea creatures such as squid and shrimp are also consumed. P. phocoena produces click-like sounds similar to those used by other cetaceans as a means of echolocation in order to locate food.(Johnston(1999), Nowak(1999))

  • Animal Foods
  • fish
  • mollusks
  • aquatic crustaceans

Economic Importance for Humans: Positive

Taken heavily in various areas, the meat is used for human and animal consumption, and its oil is used in lamps and as a lubricant.

Conservation Status

Although fishing of P. phocoena is now illegal in most areas, the species is still in danger. Deliberate and accidental deaths still occur because modern fishing nets are almost undetectable to porpoises. Since these nets are commonly used in nearshore areas, in the natural range of P. phocoena, they probably kill large numbers of porpoises. Various measures are being taken in the United States and other nations in an attempt to limit deaths of this kind. In addition to deaths related to fishing, porpoises also suffer from chemical and noise pollution. (Dollinger(1988), Johnston(1999), McWilliam(1999), Nowak(1999))

Other Comments

One interesting danger that the Harbor Porpoise may be facing is completely natural. As one group of researchers noticed, a number of porpoise carcasses taken in Scotland all had similar puncture and bruise wounds, with most of them dying as a result of internal injury. In addition to these injuries some of the specimens also had teeth gouges in their flesh. After analyzing these bite patterns, the researchers determined that the animal responsible for inflicting these wounds was Tursiops truncatus, the Bottlenosed Dolphin. At least in this area of Scotland it seems that where the two species' ranges overlap, dolphins are attacking and in some cases killing porpoises. It is not known for sure exactly what is prompting this kind of behavior. (The Porpoise Page, 1998)

Contributors

George Hammond (), Animal Diversity Web.

Andrew Masi (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Arctic Ocean

the body of water between Europe, Asia, and North America which occurs mostly north of the Arctic circle.

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

brackish water

areas with salty water, usually in coastal marshes and estuaries.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

estuarine

an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.

freshwater

mainly lives in water that is not salty.

holarctic

a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.

World Map

Found in northern North America and northern Europe or Asia.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

migratory

makes seasonal movements between breeding and wintering grounds

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

pelagic

An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).

piscivore

an animal that mainly eats fish

polar

the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Dollinger (editor), P. 1988. Convention on International Trade in Endangered Species of Wild Fauna and Flora; Identification Manual Vol I. Mammalia. Switzerland: Secretariat of the Convention.

Johnston, D. 2001. "Harbour Porpoise" (On-line). @Phocoena.org. Accessed 11/03/04 at http://phocoena.org/factsheets/harbourporp.html.

Nowak, R. 1999. Walker's Mammals of the World, 6th Ed. Vol II. Baltimore: John Hopkins University Press.

The Porpoise Page, 1998. "Harbor Porpoise" (On-line). The Porpoise Page. Accessed 11/03/04 at http://www.theporpoisepage.com/harbor.php.

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