Northern fur seal
| Northern fur seal | ||||||||||||
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Northern fur seal, bull |
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Callorhinus | ||||||||||||
| JE Gray , 1859 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Callorhinus ursinus | ||||||||||||
| ( Linnaeus , 1758) |
The Northern Fur Seal ( Callorhinus ursinus ) is a northern Pacific -based Fur seals . It has the woolly fur in common with the southern fur seals, but is not particularly closely related to them.
features
There are significant differences in size, weight, and color between males and females. The cows are gray-brown on the top and red-brown on the underside, measure around 140 cm and weigh 43 to 50 kg. Adult bulls are dark brown or gray on top and reddish brown underneath; they have a mane and are over 2 m tall and 181 to 272 kg.
Like the southern fur seals, this species also has a relatively pointed snout and dense undercoat, but differs from them by a different head shape, longer hind fins and largely bare front fins.
distribution
The colonies in which reproduction takes place in summer are limited to a few islands in the Bering Sea and the North Pacific. Large colonies can be found on the Pribilof Islands and Commander Islands in the Bering Sea , the Tyuleniy Island in the Sea of Okhotsk , the Kuril Islands and on the on the California Channel Islands belonging to San Miguel Iceland .
Outside the breeding season, fur seals wander far and wide. Some of them cover distances of 10,000 km and more. They sometimes spend several days at sea before going ashore to rest. These winter locations are on the entire west coast of North America as well as on the coasts of Kamchatka, Japan and Korea.
Way of life
Northern fur seals look for prey primarily at night. Her dives regularly lead her to depths of 70 m, sometimes even 200 m. Here they look for fish and squid. In the Bering Sea, young coalfish are the main prey near the coast, while octopuses are in the open sea. Anchovies , capelin and herrings are also often caught .
At the breeding season, on the Pribilof Islands in early June, the bulls are found on the colony islands. They try to secure a piece of coast for themselves early on. When space becomes tight, rival males will fight. Younger and weaker bulls are pushed to unattractive places that are far inland or on the edge of the colony. The strongest bulls hold the places near the coast in the middle of the future colony.
The females arrive about two weeks after the bulls. The place where they go ashore determines which harem they belong to. A male watches over one to a hundred cows. The average harem has forty females.
The females give birth to their young about two days after going ashore. Only a few days later they mate with the bull in their territory. The gestation period is almost a full year, but includes a four-month dormancy period during which the development of the fertilized egg cell is temporarily interrupted. The young are around 65 cm tall at birth, have a black coat and are immediately able to swim. But they usually don't go into the water for the first month of their life. They are suckled for three to four months by the mother who recognizes her young by their smell. Cops show no interest in the young.
Northern fur seals become sexually mature at the age of three to seven years (females) or five to six years (males). However, bulls cannot maintain a territory until they are at least ten years old and will hardly be able to mate before that. The lifespan is estimated at 20 to 25, in exceptional cases 30 years.
protection
The fur hunters have always considered fur to be the most valuable of all seals. In the late 18th century, the large fur seal colonies were discovered in the North Pacific. While the fur seals dispersed in winter, seal hunters could simply dock on the coast in summer and slaughter thousands of seals without any problems. At that time, there were about 1.5 to 2 million fur seals in the Commander Islands, 2 to 2.5 million in the Pribilof Islands, and hundreds of thousands more on other islands along the west coast of North America. In the beginning, the stocks were not endangered, as the Russian government restricted the number of catches and, for example, banned the killing of young males. When Alaska was bought by the USA in 1867 , such restrictions no longer existed. In the two years 1868 and 1869 alone, 329,000 fur seals were killed on the Pribilof Islands. In addition, the seals were harpooned at sea. By 1900 the herds on the Kuril Islands had been destroyed, and only a few individual animals were left on the commanders' islands and Tyuleniy. Only on the Pribilof Islands was there a population worth mentioning with 130,000 to 300,000 animals.
The North Pacific Fur Seal Convention , signed between the United States, Russia, Japan, and Canada in 1911 , finally introduced restrictions. All fur seals were banned until 1917, after which an annual quota of 40,000 legally killed fur seals was set. Harpooning at sea was completely prohibited. As a result of this measure, the population increased again to 2.5 million fur seals by 1940.
Since the 1940s, stocks have been declining again, albeit gradually and no longer as drastically as before. While there is geographic expansion, the large colonies on the islands in the North Pacific are getting smaller every year and are now about half the size of the 1940s. Even the complete halt to commercial fishing (since 1983) could not reverse this trend. The overfishing of the Bering Sea is probably responsible , as a result of which the fur seals are deprived of their food source. Because of the constant decline, the IUCN has now classified the northern fur seal as endangered.
Fur seals and humans
The term fur seal is sometimes used jokingly for ancient seafarers.
literature
swell
- Ronald M. Nowak: Walker's Mammals of the World . Johns Hopkins University Press, Baltimore / London 1999. ISBN 0-8018-5789-9
further reading
- Sergei V. Makarov: The Northern Fur Seal. Ziemsen, Wittenberg 1969.
- Roger L. Gentry: Behavior and Ecology of the Northern Fur Seal. University Press, Princeton NJ 1998. ISBN 0-691-03345-5
- Wilfred H. Osgood, Edward A. Preble, and George H. Parker: The Fur Seals and other Life of the Pribilof Islands, Alaska, in 1914 , Bullentin of the Bureau of Fisheries, Volume XXXIV, 1915, Document No. 820, edition June 19, 1915, Washington, United States Government Printing Office .
Web links
- Callorhinus ursinus in the endangered Red List species the IUCN 2006. Posted by: Seal Specialist Group, 1996. Retrieved on 11 May, 2006.