Burmeister's Porpoise (버마이스터돌고래)

 

 

 

 

버마이스터돌고래(Phocoena spinipinnis)

영명 : Burmeister's Porpoise

 

몸길이 : 1.8m. 등지느러미가 돌고래중에서 가장 뒤쪽에 자리하고 있다.

남아메리카 온대에서 아한대에 서식하고 있다.

 

◈ 500 마리 이하.

 

 

 

Description

The body is robust with a small, blunt head and relatively large flippers. The dorsal fin is triangular in shape and canted backward in a unusual fashion for a cetacean. The Spanish name for this porpoise "marsopa espinosa" meaning "spiny porpoise" refers to the series of tubercles present in the dorsal fin. Coloration varies from dark to brownish grey on the back and sides, and a light grey on the ventral region. A dark patch often surrounds the eye. A dark grey stripe runs from the chin to the base of the flipper. A pair of stripes is also present on the abdominal region.

Distribution

Phocoena spinipinnis ranges on the west coast of South America from Paita (05°11'S), Peru, south to Valdivia (39°46'S), Chile; on the east coast of South America from Santa Catarina (28°48'S), Brazil, south to Chubut (42°25'S), Argentina ; and in coastal waters around Tierra del Fuego.

Burmeister's Porpoise may be one of the most abundant small cetaceans living around the coasts of southern South America, but it is shy and easy to overlook, and so it is poorly known. Whether Burmeister's porpoise has a continuous distribution throughout its range is unclear. There are numerous gaps in the known distribution along both Atlantic and Pacific coasts, but it is likely that many or most of these simply reflect a lack of survey effort in the areas concerned.

 

Population size

There are no quantitative data on abundance. Burmeister's porpoise is very difficult to detect in any but calm conditions, a fact that may explain the discrepancy between the assumed abundance of this animal in coastal waters on the one hand and the relative rarity of field observations on the other. The animal's respiratory and diving behaviour does not lend itself to easy observation: swimming is highly unobtrusive, surfacing is quiescent, and relatively prolonged dives of 1~3 mm are common.

 

Habitat

This is essentially a coastal species, which sometimes frequents rivers and estuaries and, off Tierra del Fuego, is occasionally observed inside the kelp line. Its habitat preferences seem to closely resemble those of the harbour porpoise, which is typically found shoreward of the 60 m isobath, but occasionally they have been recorded offshore in up to 1000m of water. However, there have also been records from more offshore waters, 50 km from the coast of Argentina.
Burmeister's porpoise is found associated with a broad range of water temperatures. At the southern limit of its distribution near Cape Horn and Tierra del Fuego, water temperatures range from 3°C in June to about 9°C in the summer months. To the north, the species appears to be associated with temperate waters in the two major northward flowing currents of South America, the Humboldt and Falklands currents. The highest recorded temperature associated with a Burmeister's sighting was 19.5°C in Golfo San José, Argentina.

 

Behaviour

A limited number of observations indicate that it is a very shy animal. Some records suggest that small groups scatter when frightened, or approached by a boat, and regroup later. It is believed to move very close to shore after dark.

Schooling: Very little is known about the natural history of this species. Most sightings are of less than 6 individuals, but aggregations of up to 70 have been reported. Behaviour of this species is inconspicuous ; they breathe with little surface disturbance.