An enigmatic cetacean that has only been observed at sea on a handful of occasions, the spectacled porpoise (Phocoena dioptrica) is distinctive for its unusual colouration, small head, peculiar facial features, and the large dorsal fin of the male. The black upperparts contrasts sharply with the well-defined white underparts, and a white ring is conspicuous around the black eye patch, a feature that earns this species its common name. The black lips are also surrounded by white. The upper surface of the tail fluke is black and the under surface is white, although it is occasionally mottled with black. The juvenile spectacled porpoise has a dark grey back and light grey underparts (2)(4)(5)(6)(8)(9).
The spectacled porpoise is a robust animal with a rounded head and no beak. The mouth is small, and the teeth are spade- or peg-shaped. The male spectacled porpoise has a large, rounded dorsal fin, while that of the female is smaller and more triangular and both species have small flippers positioned far forward on the body (2)(4)(5)(9).
With sightings of the spectacled porpoise in the wild being extremely rare, very little is known about its biology and behaviour. It is mostly seen alone, suggesting it is primarily solitary. However, groups of three, probably consisting of a female, a calf and an additional adult, have been observed on numerous occasions (8)(9). It is very inconspicuous when surfacing, only raising the smallest portion of its body above the water to breathe, and will swim away quickly when approached by boats. Nothing is known about the migratory patterns of the spectacled porpoise, or whether it migrates at all (3)(4).
Little is known about the feeding habits of the spectacled porpoise, but based on its tooth structure and the stomach contents of four stranded individuals, it is likely that it feeds on algae, fish, squid and crustaceans(2)(4)(5)(6)(8).
The spectacled porpoise is thought to give birth between the southern spring and summer (2)(4)(5)(6). Like other porpoises, it most likely gives birth to a single calf after a gestation period of between 8 and 11 months (7). The female spectacled porpoise becomes sexually mature after reaching a length of about 1.8 metres (6).
The widely scattered records of this species from the southern Atlantic, Indian and Pacific Oceans suggest that the spectacled porpoise has a circumpolar distribution. In the Atlantic, its range is thought to extend northwards along the eastern coast of South America as far as southern Brazil, while in the Pacific it extends as far north as Tasmania and New Zealand (1)(2)(4)(5)(6)(9).
Although once thought to be a primarily coastal species, records of the spectacled porpoise around offshore islands suggest that it is an oceanic species of temperature and sub-Antarctic waters, ranging between 5.5 and 9.5 degrees Celsius. The spectacled porpoise has also been observed entering coastal waters, rivers and channels (1)(2)(4)(5).
Historically, the spectacled porpoise was killed for food and crab bait in Argentina and Chile (9), but it is not known what impact this had on the population. This species has also been accidentally captured in gillnets at Tierra del Fuego, with as many as 34 individuals killed between 1975 and 1990. There have also been occurrences of strandings in areas where there are high levels of fishing activity (1)(4). In addition, the spectacled porpoise may be threatened by disturbance from oil and mineral exploration and by offshore pollution, which can lead to the accumulation of toxins within its body (3)(6).
The conservation of the spectacled porpoise is severely restricted by a lack of information on its populations, biology, threats and distribution, and surveys are urgently required if this information is to be obtained (1). It is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning international trade in this species should be carefully regulated if it were to begin (3) and, like other cetaceans, it is protected within the Australian Whale Sanctuary under the Environment Protection and Biodiversity Conservation Act. The spectacled porpoise is also subject to International Whaling Commission regulations within the Indian Ocean Sanctuary and the Southern Ocean Sanctuary (6).
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Reeves, R.R., Smith, B.D., Crespo, E.A. and Notarbartolo di Sciari, G. (2003) Dolphins, Whales and Porpoises: 2002-2010 Conservation Action Plan for the World’s Cetaceans. IUCN/SSC Cetacean Specialist Group, IUCN, Gland. Available at: http://data.iucn.org/dbtw-wpd/edocs/2003-009.pdf
Simple plants that lack roots, stems and leaves but contain the green pigment chlorophyll. Most occur in marine and freshwater habitats.
A whale, dolphin or porpoise.
A group comprising all whales, dolphins and porpoises.
Diverse group of arthropods (a phylum of animals with jointed limbs and a hard chitinous exoskeleton) characterised by the possession of two pairs of antennae, one pair of mandibles (parts of the mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps and barnacles.
The unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans.
The state of being pregnant; the period from conception to birth.
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