Northern fur seal (English spelling) Callorhinus ursinus; northern fur seal

Japanese: キタオットセイ（英語表記）Callorhinus ursinus; northern fur seal

Carnivora, Pinnipedia, Otariidae, Genus Otariidae. This species is usually referred to as the fur seal. Males reach a body length of about 2.1 m and a weight of about 270 kg, while females reach a body length of about 1.5 m and a weight of about 50 kg. Birth length is 60-65 cm, birth weight is about 5.4-6 kg. The body hair consists of stiff, coarse supercilium and thin, soft undercoat. The back is black-brown or dark brownish gray, and the abdomen is slightly lighter. The color of the body hair changes as the animal grows, and is black at birth. The body is spindle-shaped, the limbs are relatively long, and the palms are fin-shaped, black, and hairless. The head is small and rounded, and the snout is short and wide and protrudes forward. The nostrils are wide and short, and the palate is narrow. The forehead of mature males is swollen. The ears are small. The tail is very small and is hidden between the hind legs. There are six incisors on the upper jaw and four on the lower jaw, two canines on the upper jaw and two on the lower jaw, and twelve cheek teeth on the upper jaw and ten on the lower jaw. Pinnipeds spend most of their time in the mid-ocean. They usually live in groups of one or two, and rest and groom while drifting on the surface of the sea. Their main breeding grounds are the Pribilof Islands and the Commander Islands, where they remain from summer to autumn. They are typically polygamous, with males usually arriving at the breeding grounds earlier than females and forming territories through fighting. The breeding season in the Pribilof Islands is from mid-June to August, with the peak season being in early July. They have a wide feeding range, and feed mainly at night on surface and mid-water fish and squids. They are widely distributed in the North Pacific Ocean, the Bering Sea, and the Sea of Okhotsk. Prized as a top-quality fur, its population was drastically reduced due to overfishing, but conservation efforts were made, such as the signing of the Northern Fur Seal Convention in 1957 between Japan, the United States, Canada, and the Soviet Union (which expired in 1988), and commercial capture has not taken place since 1984.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

食肉目鰭脚亜目アシカ科オットセイ属。通常オットセイと呼ばれるものは本種をさす。雄は体長約 2.1m，体重約 270kg，雌は体長約 1.5m，体重約 50kgに達する。出生体長 60～65cm，出生体重約 5.4～6kg。体毛は硬く粗い上毛と細く柔らかい下毛から成る。背部は黒茶色または濃い茶ねずみ色で，腹部はやや淡い。体毛の色は成長に伴い変化し，出生時は黒色である。体は紡錘形で四肢が比較的長く，掌部は鰭 (ひれ) 状で黒色を呈し毛はない。頭部は小さく丸みを帯び，吻部は短く幅広で前方に突出する。鼻孔は幅広で短く，口蓋部は狭い。成熟した雄は前頭部が膨満する。耳介は小さい。尾はきわめて小さく後肢の間に隠れる。門歯は上顎6本，下顎4本，犬歯は上顎と下顎に各2本，頬歯は上顎 12本，下顎 10本である。鰭脚類中海上で過す時間が最も長い。通常1～2頭で行動し，海面を漂いながら休息したり，毛繕いをする。おもな繁殖地はプリビロフ諸島やコマンドル諸島で，夏から秋までとどまる。典型的な一夫多妻で，通常雄は雌より早く繁殖場に上陸し，闘争によってなわばりを形成する。プリビロフ諸島における繁殖期は6月中旬から8月で，最盛期は7月初旬。食性範囲は広く表層および中層に生息する魚類やスルメイカ類を，もっぱら夜間に捕食する。北太平洋，ベーリング海，オホーツク海に広く分布する。最上級の毛皮として珍重され，乱獲により著しく減少したが，1957年日本，アメリカ，カナダ，ソ連の4ヵ国間でオットセイ保護条約 (1988年失効) が結ばれるなど保護活動が進められ，84年を最後に商業捕獲は行われていない。

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