Sei Whale (정어리고래)

 

정어리고래(Balaenoptera borealis)

영명 : Sei Whale

 

북반구 : 몸길이 - 14∼14.8m, 몸무게 : 15.9~17.8t. 남밤구 - 몸길이 : 14.7~15.5m, 몸무게 : 18.5~20.4t. 멸치고래, 보리고래 라고도 한다. 세계 어느 바다에서나 회유하지만 빙해에는 들어가지 않는다. 출생후 6∼12년이 지나면 성숙하며, 몸은 비교적 호리호리한 방추형이며, 등은 검은색이고, 배는 흰색이다. 가슴과 배에 주름살이 60∼65개 있지만, 배꼽까지 미치지는 못한다. 등지느러미가 뚜렷하다. 다른 긴수염고래에 비해 등지느러미가 상대적으로 크고, 앞쪽으로 치우쳐 있다. 입 속에 수염이 300∼350개 나 있으며, 안쪽의 털은 양털과 같이 부드럽고 빽빽하게 나 있어 부유성의 작은 새우류를 걸러먹는 데 알맞게 발달되어 있다.

 

무리를 이루어 다니는 정어리 등과 함께 회유하면서 잡아먹으므로 정어리고래라고 하게 되었다. 번식기는 12∼1월이며, 2∼3년에 1번씩 한배에 1마리를 낳는다. 임신기간 약 10.5개월이고, 1년 이내에 젖떼기를 한다. 자연감소를 방지하기 위해 아이슬란드 이외에서는 포획이 금지되고 있다. 적도 바로 아래와 극역을 제외한 전해역에 서식한다.

 

◈ 북태평양 (동격해역) : 28,400 마리.

◈ 북대서양 : 4,000 마리.

◈ 남반구 (인도양 포함, 30° 이남) : 9,720~12,000 마리. 

 

      

               

 

               

 

                   

 

               

 

               

 

                   

 

               

 

               

 

Description
The sei whale is smaller in size than the fin whale (Balaenoptera physalus), and can be distinguished from this similar species because it has symmetrical colouring on the lower parts of its head. It is also similar to Bryde's whale (Balaenoptera edeni), but has only one ridge on the upper surface of the head, whereas Bryde's whale has three. The 'blow' or spout of the sei whale is a single thin cloud, which reaches about 3 metres in height. The skin is a mottled dark grey colour, with white grooves along the paler underparts. The baleen is grey to black with paler fringes and reaches 78cm in length. The dorsal fin is obvious, has a slightly hooked shape and is located two-thirds along the length of the body. The common name 'sei' arose from the arrival of this whale off the coast of Norway tending to coincide with that of coalfish 'seje'.

 

Range
Found in almost every ocean of the world, but occurs less frequently in polar waters than the other members of this family.

 

Habitat
An inhabitant of the open ocean, the sei whale tends to avoid coastal waters.

 

Biology
Few details of the natural history of this whale are known. They tend to occur in groups of between 2 and 5 individuals, but larger groups may form in areas where food is very abundant. Capable of travelling at great speed, this species is believed to migrate into warmer waters at lower latitudes during the winter months. Little is known of communication in this species, but individuals are known to make many low frequency sounds.

 

Threats
Although not a traditional target of the whaling industry, the sei whale began to be exploited after the blue, fin and humpback stocks became depleted and protected. This species was then relentlessly hunted in the 1960s and 70s, before the International Moratorium on Commercial Whaling went into effect in 1986. At present, the species is vulnerable to chemical and noise pollution.

 

Conservation
In 1976, this whale received protected status, and the moratorium on commercial whaling took effect from 1986. There are ongoing problems with the moratorium however, and Iceland announced in 2001 that it might soon resume commercial whaling of sei, minke and fin whales. Other countries also oppose the ban and the future of endangered species such as the sei whale is not yet secure. There are signs however, that populations of this little known cetacean are starting to recover from past exploitation.

 

Status : CITES - Appendix I. IUCN ; Endangered