Table of Contents
Overview
Distribution
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Range Description
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Geographic Range
Spectacled porpoises are rarely seen and are found only in the oceans of the southern hemisphere. Usually they are found near the southern east coast of South America (from Uruguay and Argentina to Cape Horn) and also near the Falkland Islands and South Georgia. Phocoena dioptrica have been seen near New Zealand, Macquarie Island and the Auckland Islands in the Pacific Ocean, and Heard Island and the Kerguelen Islands in the Indian Ocean.
Biogeographic Regions: indian ocean (Native ); atlantic ocean (Native ); pacific ocean (Native )
- Minasian, S., K. Balcomb, L. Foster. 1984. The World's Whales: The Complete Illustrated Guide. Washington, D.C.: Smithsonian Books.
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Brownell, R. November 21, 1975. <
>. Mammalian Species Special Publication of the American Society of Mammalogists, No. 66: 1-3. - Coffey, D. 1977. Dolphins, Whales and Porpoises: An Encyclopedia of Sea Mammals. New York: Macmillan Publishing Co., Inc..
- Tinker, S. 1988. Whales of the World. Honolulu, Hawaii: Bess Press Inc..
- Bannister, J., C. Kemper, R. Warneke. September 1996. "The Action Plan for Australian Cetaceans" (On-line). Accessed November 28, 2001 at http://www.deh.gov.au/coasts/species/cetaceans/actionplan/whaleap5a.html.
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Physical Description
Morphology
Physical Description
Size of this species can vary from about 1.25 meters (females) to 2.24 meters (males). The average weight of P. dioptrica varies from 55 to 80 kilograms; the largest individual found was 115 kilograms. The dorsal side is a blue-black color and the ventral side is pure white. There is a sharp line that divides the dorsal black color from the ventral white color. There is a gray line that goes from the corners of the mouth to the leading edge of the pectoral flippers, which are white. The lips are also black and the eyes are surrounded by black circles that look like glasses. The tail fluke is dark on the top side and white on the bottom. Shape also distinguishes this species. The dorsal fin is big and triangular and the pectoral fins are small and rounded when compared to other Phocoena species. The teeth in the upper jaw number between 18 and 23 and the teeth in the lower jaw number between 16 and 19 on each side. The teeth have spade-shaped crowns, which is a distinguishing characteristic of porpoises when compared to dolphins, which have cone-shaped crowns. There also are some skull features that distinguish P. dioptrica from P. phocoena: the top of the rostrum of P. dioptrica is flatter, and from the side, the premaxillary bones of P. dioptrica are less visible.
Range mass: 115 (high) kg.
Average mass: 55-80 kg.
Range length: 1.25 to 2.24 m.
Average length: 2 males, 1.8 females m.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
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Ecology
Habitat
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Habitat and Ecology
Only four stomachs have been examined; the contents included anchovies and stomatopods (mantis shrimp).
Systems
- Marine
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Spectacled porpoises prefer cold ocean waters of the southern hemisphere. They normally live near offshore islands but are sometimes found in the open ocean. They seem to prefer the subantarctic area where there are cold currents like the Falkland Current.
Habitat Regions: temperate ; saltwater or marine
Aquatic Biomes: pelagic ; coastal
- Nowak, R. 1999. Walker's Mammals of the World. Baltimore and London: Johns Hopkins University Press.
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Trophic Strategy
Food Habits
The food preferences of spectacled porpoises are not well known. They are most likely similar to other porpoises, which eat fish, squid, and crustaceans.
Animal Foods: fish; mollusks; aquatic crustaceans
Primary Diet: carnivore (Piscivore )
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Associations
Ecosystem Roles
Porpoises are predators of fish and aquatic invertebrates, and they sometimes provide a food source to killer whales. Nothing specific is known about the role of P. dioptrica in the ecosystem.
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Predation
Nothing is recorded about predation of P. dioptrica. It is possible that killer whales are their only natural predators. They also are hunted by humans.
Known Predators:
- killer whales (Orcinus orca)
- humans (Homo sapiens)
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Life History and Behavior
Behavior
Communication and Perception
Nothing has been recorded about the communication or perception of P. dioptrica, but they probably use echolocation as do other porpoises.
Perception Channels: echolocation
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Life Expectancy
Lifespan/Longevity
The lifespan of P. dioptrica is unknown.
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Reproduction
No information is available on the mating systems of this species.
All mammals reproduce sexually via internal fertilization and all eutherian mammals give birth to live young. However, very little else is known about the reproductive behaviors of P. dioptrica. One near-term fetus was recorded in July 1912 and another was taken in August of the same year. The first fetus was a female and was 484 millimeters long. No information was recorded on the second fetus. The young are most likely born in early spring, but no information is recorded.
Key Reproductive Features: iteroparous ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization ; viviparous
A feature common to all eutherian mammals is that females nuture their young inside their bodies until birth, and afterwards provide them with milk. However, no specific information on parental investment is available for P. dioptrica.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)
- Minasian, S., K. Balcomb, L. Foster. 1984. The World's Whales: The Complete Illustrated Guide. Washington, D.C.: Smithsonian Books.
-
Brownell, R. November 21, 1975. <
>. Mammalian Species Special Publication of the American Society of Mammalogists, No. 66: 1-3. - Tinker, S. 1988. Whales of the World. Honolulu, Hawaii: Bess Press Inc..
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Conservation
Conservation Status
IUCN Red List Assessment
Red List Category
Red List Criteria
Version
Year Assessed
Assessor/s
Reviewer/s
Contributor/s
Justification
History
- 1996Data Deficient
- 1996Data Deficient
- 1994Insufficiently Known(Groombridge 1994)
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Not enough information is known about this species in order to list it as endangered.
US Migratory Bird Act: no special status
US Federal List: no special status
CITES: appendix ii
IUCN Red List of Threatened Species: data deficient
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Trends
Population
Population Trend
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Threats
Like all phocoenoids, spectacled porpoises are caught in gillnets. At least 34 animals were killed incidentally between 1975 and 1990 in coastal gill nets set in Tierra del Fuego, and there was a co-occurrence of strandings and fishing activity in southeastern Chile, suggesting additional undocumented mortality from this source. Some mortality of spectacled porpoises was also reported from bottom and mid-water trawls off the coast of Chubut, Argentina (Brownell and Clapham, 1999).
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Management
Conservation Actions
Estimates of abundance are needed as well as information on direct and incidental takes.
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Relevance to Humans and Ecosystems
Benefits
Economic Importance for Humans: Negative
Spectacled porpoises have no recorded adverse affects on humans.
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Economic Importance for Humans: Positive
Native people in South America hunt P. dioptrica, but not for commercial uses.
Positive Impacts: food
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Risks
IUCN Red List Category
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IUCN (2008) Cetacean update of the 2008 IUCN Red List of Threatened Species.
http://www.marinespecies.org/aphia.php?p=sourcedetails&id=125373
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Wikipedia
Spectacled porpoise
The spectacled porpoise (Phocoena dioptrica) is a rarely seen member of the porpoise family. The species is readily distinguished from other porpoises by a characteristic dark ring around the eyes, which gives the animals their name. This ring is commonly surrounded by a farther lighter ring.
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Taxonomy
The spectacled porpoise was first described by Lahille in 1912 from a specimen found on a beach near Buenos Aires. A skull later found in Tierra del Fuego was initially thought to be another species, provisionally named Phocoena dioptrica but the individual was later shown to be a spectacled porpoise and this name remains a synonym. The Latin word dioptrica refers to the double eye rings characterizing the creature.
Physical description
The spectacled porpoise is a robust creature with a small head and no beak. Spectacled porpoises have distinctive black and white markings - black above and white underneath. They have black eyes with white rings or spectacles, and a white stripe on the upper surface of the tail. They have a large rounded dorsal fin, and no beak. Like all porpoises, they have spade-shaped teeth (as opposed to conical in dolphins). Newborn members of this species are about 80 cm with males growing up to 2.2 metres and females somewhat smaller. The age at which they reach maturity, as well as the porpoise's longevity, is unknown. They can grow up to 60–84 kg (130-185 lbs) in weight as adults.
Diet
These porpoises feed on squid and fish, yet also on octopus, shrimp, molluscs, and other crustaceans.
Behaviour
Spectacled porpoises live in groups of 1-25. They are fast, active swimmers, and they normally avoid boats. Little else is known about their behaviour as most of the information has been gleaned from stranded individuals.
Distribution and population
The spectacled porpoise is believed to be circumpolar in cool sub-Antarctic and low Antarctic waters. Many skeletons have been found on Tierra del Fuego and this area is believed to be a site of relatively high concentration. This species has been seen off Brazil, the Falkland Islands and South Georgia in the Atlantic, off Auckland, Tasmania and south Australia in the South Pacific and Heard Island and Kerguelen in the southern Indian Ocean. Individuals have very rarely been seen in the open sea. The southernmost sighting was in the Drake Passage at 58° S.
The total population is unknown. The IUCN lists it as a data deficient species in the Red List of Threatened Species.
Conservation
The spectacled porpoise is listed on appendix II[1] of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). It is listed on Appendix II[1] as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.
See also
References
- ^ a b "Appendix II" of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). As amended by the Conference of the Parties in 1985, 1988, 1991, 1994, 1997, 1999, 2002, 2005 and 2008. Effective: 5th March 2009.
- 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 dioptrica. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 24 March 2009. Database entry includes justification for why this species is listed as data deficient
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Unreviewed
