White Whale (흰돌고래)

 

흰돌고래(Delphinapterus leucas)

영명 : White Whale, Beluga

 

몸길이 : 3.6~4.2m, 몸무게 : 1~1.5t. 몸빛은 희고, 꼬리지느러미 뒤쪽 가장자리에 깊이 벤 자리가 있다. 울음소리가 아름답다. 머리가 작은 반면 둥글고 이마가 높다. 부리는 있으나 매우 짧다. 가슴지느러미가 짧고 넓으며 앞부분이 크게 볼록하다. 머리와 몸체 사이에 목이 관찰된다. 목을 90˚가까이 좌우로 구부릴 수 있을 만큼 유연하며 피부가 매우 부드럽다. 일각과에 속하지만 이빨로 된 뿔은 없다. 위턱에 9쌍, 아래턱에 8쌍의 이빨이 있다. Delphinapterus 는 날개가 없는 돌고래라는 뜻이다. 출생 직후의 몸길이는 1.5m이며, 암컷은 5∼6세, 수컷은 8∼9세에 성숙한다.

 

사람에게 잘 길들여지며, 잠수한 채로 2∼3㎞까지 이동할 수 있다. 물 속에서 카나리아와 비슷한 울음소리를 낸다. 주로 오징어, 연어, 청어, 갑각류 등을 먹는다. 보통 5∼10마리가 무리지어 회유하나, 번식기에는 100∼200마리의 무리를 이룬다. 번식기는 봄이고, 임신기간은 약 14개월이며, 2∼3년에 한배에 1마리를 출산한다. 수유기간은 약 2년이다. 일생 동안 한 집단 안에서 생활한다. 북극에 살고 있는 사람들에게 기름과 가죽을 제공해 주는 귀중한 동물이다.

1997년 8월 부산 다대포 내만에 회유한 기록이 있는데 동해 북부에 분포할 가능성이 크다. 북극권에서 아북극권, 북극해를 중심으로 대서양, 베링해, 오호츠크해, 뷰포트해에서 서식하고 있다.

 

◈ 태평양 (캐나다 연안) : 45,700 마리.

◈ 북태평양 (러시아 연안) : 9,500 마리.

◈ 북태평양 (알래스카 연안) : 5,800 마리.

◈ 북대서양 (러시아) : 27,000 마리.

 

 

 

 

 

 

 

 

 

◈ 흰돌고래가 서식하는 장소와 개체수는
1. Cook Inlet : 347 마리
2. Bristol Bay : 1,100 마리
3. East Bering Sea : 12,675 마리
4. East Chuckchi Sea : 3,700 마리
5. Beaufort Sea : 39,257 마리
6. North Water (Baffin Bay) : 28,000 마리
7. West Greenland : 2,000 마리
8. Cumberland Sound : 485 마리
9. Frobisher Bay : No info
10. Ungava Bay < 50 마리
11. West Hudson Nay : 25,100 마리
12. Foxe Basin : 1,000 마리
13. South Hudson Bay : 1,299 마리
14. James Bay : 3,300 마리
15. East Hudson Bay : 1,014 마리
16. St Lawrence River : 1,238 마리
17. Svalbard : 300~3,000 마리
18~24. West Siberia (Barents - Laptev Sea) : 500~1,000 마리
25. East Siberia (West Chukchi - East Siberian Sea) : 2,000~3,000 마리
26. Anadyr Delta : 200~3,000 마리
27~29. Sea of Okhotsk : 18,000~20,000 마리

 

Description
The snow-white beluga whale is one of the most distinctive of all cetaceans (a group that includes, dolphins, whales and porpoises). The stocky body ends in a particularly small head, and adults develop their striking white colouring as they mature. Belugas lack a dorsal fin, their genus name 'Delphinapterus' means 'dolphin-without-a-wing', but there is a ridge of toughened skin along the back that tends to be more pronounced in mature males. Unlike most cetaceans, belugas have an extremely flexible neck and can turn their head almost 90° to the side; their lips are also flexible, forming a variety of facial expressions. Belugas use a wide range of vocalisations such as clicks, grunts, squeals, screeches and whistles. These sounds can be heard through the hulls of ships and the beluga was nicknamed the 'sea canary' by early Arctic sailors. They have a very thick layer of blubber that provides insulation in the freezing arctic waters ; this layer may be up to 15cm thick and as much as 80% of their body weight is blubber.

 

Range
Belugas are found in Arctic waters around northern Russia, North America, Greenland and the Norwegian archipelago of Svalbard. Most populations migrate north in the spring, then south in the autumn once the ice starts to form.

 

Habitat
Inhabits cold arctic waters, usually near to the ice edge. Spends summer in shallow bays and estuaries and winters in areas of loose pack ice, where wind and ocean currents keeps cracks for breathing holes open.

 

Biology
Belugas are highly social animals, and in the summer months thousands of individuals can be seen gathered in estuaries ; often females with calves will come together whilst males form large bachelor groups. Females are sexually mature at around 4~7 years of age, they give birth to a single calf after a gestation period that lasts just over a year. Mother and calf have an extremely strong bond, swimming very closely together, and the calf will continue to feed on its mothers milk until well into its second year. Belugas are able to dive to depths of over 1,000 metres but spend most of their time on the surface of the water swimming slowly. During winter months it may be necessary for individuals to create breathing holes in the ice, which they can do with their heavy head and back. The flippers are capable of a wide-range of movement and enable belugas to manoeuvre themselves effectively. In summer months, large numbers of belugas gather in estuaries in order to moult; they rub themselves on the gravel bed and shed the yellow, withered skin of the previous year to once again become gleaming white.

Belugas feed on a wide variety of fish, bottom-dwelling crustaceans and worms ; most of the prey is found on the seabed and it is thought that the highly flexible lips may be used to suck prey into the mouth. Sounds can be used to detect prey; the enlarged melon is an electro-receptor for sounds that are sent out from the nasal passages. These whales are thought to live for up to 50 years, killer whales and polar bears prey upon them, and belugas are particularly vulnerable if trapped by the ice.

 

Threats
Belugas have traditionally been hunted for their blubber for many centuries, but only with the advent of commercial whaling did the harvest become too large to sustain. These whales are particularly vulnerable, due to their high fidelity for certain migratory routes. It is estimated that between 1874 and 1911, Scotland alone was responsible for killing over 11,000 whales. Perhaps the most pertinent threat to the beluga today, is habitat deterioration in the form of the industrial development and pollution of coastal habitats with which they are particularly associated. Some populations are declining principally as a result of pollution; belugas in the St Lawrence River Estuary, for example, accumulate so many toxins that deformed calves are prevalent and dead individuals are treated as toxic waste.

 

Conservation
Today the widespread hunting of beluga whales is prohibited under the International Moratorium on Commercial Whaling, however, small quotas are permitted to local people who depend upon the harvest. The Alaska and Inuvialuit Beluga Whale Committee was established in 1988 and encourages dialogue between native hunters, conservationists and government representatives as well as carrying out stock and hunting assessment of the Alaskan and Canadian populations of belugas. Some protection from industrial development is being provided at locations where these whales commonly occur but careful monitoring of existing stocks will be needed to secure the future of this attractive cetacean.

 

Status : CITES - Appendix II. IUCN ; Vulnerable