Zalophus japonicus

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Kingdom Animalia

 Japanese Sea Lion, stuffed specimen at Tennōji Zoo, Osaka, Japan. Photographed by Nkensei in November 2006. This image has been released under the GNU Free Documentation License. Source: Wikimedia Commons.

Phylum Chordata
Class Mammalia
Order Carnivora
Suborder Pinnipedia
Family Otariidae
Subfamily Otariinae
Genus Zalophus
Species Zalophus japonicus
Authority (Peters, 1866)
 
English Name Japanese Sea Lion, Japanese Sealion
Czech Name Lachtan japonský
Dutch Name Japanse Zeeleeuw
French Name Otarie du Japon, Otarie Japonaise
German Name Japanischer Seelöwe
Italian Name Leone Marino Giapponese
Japanese Name ニホンアシカ
Korean Name 일본강치
Polish Name Uchatka Japońska
Portuguese Name Leão-marinho-do-Japão
Spanish Name León Marino de Japón
Swedish Name Japanskt Sjölejon
 
Synonyms Zalophus lobatus Jentink, 1892; Zalophus californianus japonicus (Peters, 1866)
 
Taxonomy Before 2003, the Japanese Sea Lion was classified as Zalophus californianus japonicus. It was raised to species level following Wozencraft in Wilson and Reeder (2005): "Rice (1998), followed here, argued for the retention of japonicus, californianus, and wollenbaeki as distinct species. Itoo (1985) concluded that japonicus was distinct, and behavioural differences separate californianus and wollenbaeki (Eibl-Eibesfeldt, 1984). Itoo classified the Japanese Sea Lion as a separate species because the skulls of modern specimens were larger and wider in proportion than that of the California Sea Lion (Sakahira and Niimi 2007).

The first report on a genetic analysis of the Japanese sea lion concluded: "the distinctly divergent cluster of Japanese sea lions reflected the morphological classification of these animals as a distinct species of the genus Zalophus; however, proximity to the California sea lion cluster simultaneously implied conformation with the traditional classification of these animals as a subspecies of Zalophus californianus" (Sakahira and Niimi 2007). Molecular evidence supports treating the Galápagos sea lion, the Californian sea lion and the Japanese sea lion by the name of species Zalophus wollebaeki and Zalophus californianus and Zalophus japonicus, respectively (Wolf et al 2007).

 
Characteristics Male Japanese Sea Lions were dark grey and weighed up to 450 to 560 kg reaching lengths of 2.3 to 2.5 meters; these were larger than male California Sea Lions. Females were significantly smaller at 1.64 meters long with a lighter colour than the males. (Wikipedia contributors 2008)
 
Range & Habitat Japanese Sea Lions were known from the northwest Pacific where it primarily occurred in the Sea of Japan along the coastal areas of the Korean Peninsula, the coasts of the Japanese Archipelago, the Kuril islands, and southern tip of the Kamchatka Peninsula. (Seal Specialist Group 1996; Wikipedia contributors 2008)

The species was known to occupy marine waters and coastal areas. Rarely found more than 16 km out to sea and frequently hauling onto shore areas throughout the year, this species breeds mainly on flat, open, sandy beaches, and sometimes in rocky areas (Seal Specialist Group 1996).

Image: map of the former distribution range of the Japanese Sea Lion (in red). Based on a map in Wolf et al. 2007. Created by Peter Maas for The Extinction Website. This image has been released under the Creative Commons Attribution Non-commercial No Derivatives 3.0 Licence.

 
Reproduction They usually bred on flat, open and sandy beaches but rarely in rocky areas (Wikipedia contributors 2008). 
 
History & Population Very little is known about the history of the Japanese sea lion. The Japanese and California Sea Lions were estimated to have diverged 2.2 million years ago, in the late Pliocene Epoch (Sakahira and Niimi 2007). Many bones of Japanese Sea Lion have been excavated from shell middens in Jōmon period (about 14,000 BCE to 400 BCE) in Japan (Niimi 1990; National Museum of Japanese History 2008) while an 18th century's Japanese encyclopedia, Wakan Sansai Zue describes that the meat was not tasty and they were only used to render oil for oil lamps (Terajima 1712). In 1866, the director of the Berlin natural history museum, Wilhelm Peters, described the Japanese Sea Lion as a separate species (Van den Hoek Ostende 1999). Harvest records from Japanese commercial fishermen in the early 1900s show that as many as 3,200 sea lions were harvested at the turn of the century and overhunting caused harvest numbers to fall drastically to 300 sea lions by 1915 and to few dozen sea lions by the 1930s. Commercial harvest of Japanese sea lions ended in the 1940s when the species became virtually extinct. In total, Japanese trawlers harvested as many as 16,500 sea lions, enough to cause their extinction. (Wikipedia contributors 2008) The last reliable report mentioned the presence in 1951 of 50-60 animals on Liancourt Rocks (Dokdo in Korean, and Takeshima in Japanese), a small rocky island which came under Korean rule after World War II (Rice 1998; Van den Hoek Ostende 1999). Individual sightings reported in the 1960's and 1970's, including a possible juvenile captured in 1974 off the coast of Rebun Island, northern Hokkaido, cannot be confirmed as confusion with escaped California Sea Lion cannot be ruled out (Seal Specialist Group 1996).
 
Extinction Causes Sea lions have been captured for the circus trade and have also been exploited for their skin and oil. Certain internal organs were also valuable in Oriental medicine and its whiskers were reportedly used as pipe cleaners. However, the main reason for the extinction of the Japanese Sea Lion is thought to be persecution by fishermen. (Seal Specialist Group 1996) Rumour has it that Korean soldiers used sea lions in shooting practices (Van den Hoek Ostende 1999).
 
Conservation Attempts A former fisherman of the Oki Islands stated that they worked to protect the sea lion population to ensure perpetuity of the resource before WWII (Wikipedia contributors 2008).
 
Reintroduction The Korean Environment Ministry has announced that South and North Korea, Russia and China will collaborate on bringing back the Japanese Sea Lion in the Sea of Japan. The ministry said "while the animals are close to extinction in South Korea and Japan, it is possible that there are some in Chinese and Russian waters". The four countries will conduct joint research by 2010. If they manage to find one in these countries, then the government will bring some to the Sea of Japan, but if not, it plans to bring some California Sea Lion (Zalophus californianus) from the United States. (Bae 2007)
 
Museum Specimens Several mounted specimens can be found in Japan (Wikipedia contributors 2008). The National Museum of Natural History 'Naturalis' in Leiden, the Netherlands, has three mounted specimens, a skeleton and four skulls (Van den Hoek Ostende 1999). The British Museum is holding one skin and four skulls (Wikipedia contributors 2008).
 
Relatives The genus Zalophus includes only includes only three species, including the extinct Japanese Sea Lion. The other two surviving species are the California Sea Lion (Zalophus californianus) and the Galápagos Sea Lion (Zalophus wollebaeki).

California Sea Lion (Zalophus californianus) and the Galápagos Sea Lion (Zalophus wollebaeki)

Images: the left-hand image shows a California Sea Lion in Point Lobos State Reserve, Monterey, California, USA. Photograped by Tewy at 13 July 2006 (source: Wikimedia Commons). The right-hand image shows a Galápagos Sea Lion. Photographed by Marc Figueras at 21 September 2004, Galápagos Islands (source: Wikimedia Commons). Both images have been released under the Creative Commons Attribution ShareAlike 2.5 Licence.

 
Links

IUCN Red List of Threatened Species: Zalophus japonicus

Japanese Sea Lion - Wikipedia, the free encyclopedia

 

References

(Complete website)

Bae Ji-sook. (2007) Extinct Sea Lions to Bring Back to Korea. The Korea Times, 5 September 2007.

Eibl-Eibesfeldt, I. 1984. The Galapagos seals. Part 1. Natural history of the Galapagos sea lion (Zalophus californianus wollebaeki, Sivertsen). Pp. 207-214, In, Key environments: Galapagos (R. Perry, ed.). Pergamon Press. Oxford, 321 pp.

Itoo, T. 1985. New cranial materials of the Japanese sea lion, Zalophus californianus japonicus (Peters, 1866). Journal of the Mammalogical Society of Japan, 10:135-148.

Niimi Michiko (1990) Sea Mammal Hunting of the Jomon Culture in Hokkaido, Bulletin of the Department of Archaeology, 9: 137-171, University of Tokyo. ISSN 02873850.

National Museum of Japanese History. (2008) The Jomon people in the northern Island. Downloaded on 9 March 2008 from http://www.rekihaku.ac.jp/e_news/index53.html

Nowak, R.M. (ed.) 1999. Walkers Mammals of the World. Sixth edition. The Johns Hopkins University Press, Baltimore and London.

Reijnders, P., Brasseur, S., van der Toorn, J., van der Wolf, P., Boyd, I., Harwood, J., Lavigne, D. and Lowry, L. 1993. Seals, Fur Seals, Sea Lions, and Walrus. Status survey and conservation action plan. IUCN/SSC Seal Specialist Group. IUCN, Gland, Switzerland.

Rice, D.W. 1998. Marine Mammals of the World. Systematics and Distribution. Special Publication Number 4. The Society for Marine Mamalogy, Lawrence, Kansas.

Sakahira, F. and M. Niimi. (2007) Ancient DNA Analysis of the Japanese Sea Lion (Zalophus californianus japonicus Peters, 1866): Preliminary Results Using Mitochondrial Control-Region Sequences. Zoological Science 24: 81–85.

Scheffer, V.B. (1958) Seals, Sea Lions and Walruses: A Review of the Pinnipedia. Stanford California: Stanford University Press.

Seal Specialist Group 1996. Zalophus japonicus. In: IUCN 2007. 2007 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 07 March 2008.

Terajima Ryōan, Wakan Sansai Zue (ca. 1712), vol. 38, Amimals, p. 72, sea lion and fur seal. (Available online) "其肉亦不甘美 唯熬油為燈油 (the meat is not tasty and just used to render oil for oil lamps.)".

Van den Hoek Ostende. 1999. Japanese sea lion - No longer surviving. 300 Pearls - Museum highlights of natural diversity. Downloaded on 8 March 2008. 

Wikipedia contributors (2008), "Japanese Sea Lion," Wikipedia, The Free Encyclopedia, http://en.wikipedia.org/w/index.php?title=Japanese_Sea_Lion&oldid=196736131 (accessed March 8, 2008).

Wilson, D.E. & DeeAnn M. Reeder (editors). 2005. Mammal Species of the World. A Taxonomic and Geographic Reference (3rd ed), Johns Hopkins University Press, 2,142 pp. (Available online)

Wolf, J.B.W., D. Tautz, F. Trillmich. (2007) Galápagos and Californian sea lions are separate species: Genetic analysis of the genus Zalophus and its implications for conservation management. Frontiers in Zoology 2007, 4:20.

Last updated: 9th March 2008.

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