Conservation Biology

Japanese sea lion

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Japanese sea lion Zalophus japonicus (By Pagemoral (Contributor Pagemoral takes a photograph) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0-2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons)

Also known as the Black sea lion, the Japanese sea lion (Scientific name: Zalophus japonicus) is a species that is believed to have become extinct in the 1950s. The species was one of 16 species of marine mammals in the family of Eared seals which include sea lions and fur seals. Together with the families of true seals and Walruses, Eared seals form the group of marine mammals known as pinnipeds.

 

caption Japanese sea lion (stuffed specimen at Tenn?ji Zoo, Osaka, Japan.) Source: Nkensei/Wikipedia based on Wolf et. al. (further reading #10)

 

 Conservation Status

 

Scientific Classification

Kingdom: Anamalia (Animals)
Phylum:--- Chordata
Class:------ Mammalia (Mammals)
Order:-------- Carnivora (Carnivores)
Family:-------- Otariidae (Eared Seals)
Genus:----------Zalophus
Species:-----------  Zalophus japonicus (Peters, 1866)

Eared seals  differ from the true seals in having small external earflaps and hind flippers that can be turned to face forwards. Together with strong front flippers, this gives them extra mobility on land and an adult fur seal can move extremely fast across the beach if it has to. They also use their front flippers for swimming, whereas true seals use their hind flippers.

It is estimated that 30,000 to 50,000 Japanese sea lions existed in the mid-19th century.

The last reliable observation of Japanese sea lions occured in 1951 and was a report of 50 to 60 individuals on Liancort Rocks (Japanese - Takeshima;  Korean - Dokto or Tokdo), in the Sea of Japan.

Sightings have been reported as recently as 1974 and 1975. However, these are not considered likely and are generally believed to have been of errant or escaped California sea lions which are quite similar in appearance.

Until recently, it was believed that the Japanese sea lion was sub species of the Californian sea lion. However, recent studies of DNA suggest that it was a separate species.

The range of this species was the northwest Pacific, along the coasts of Japan, the Korean peninsula, and the Russia's, Sakhalin Island.

The common name “black sea lion” suggests that this species (or probably its adult males), were very dark brown or black in coloring; which is similar to many adult male California sea lions. A colour photograph and description from the mid-19th century indicates the Japanese sea lion as “straw coloured with a darker throat and chest in the female.”

 

caption Estimated range of the Japanese sea lion. Source: Peter Maas/The Extinction Website based on

Adult males are believed to to be about 2.5 meters in length and adult females about 1.4 meters, while a four-month-old pup was 65 cm long and 9 kg.

Japanese sea lions were known to exist just coastal areas, rarely being sighted more that 16 km out to sea. It was observed to come ashore throughout the year and breed primarily on sandy beaches, but sometimes on rocky shores.

Like most eared seals, Japanese Sea Lions were hunted for their skin and oil. In addition certain internal organs were used for medicine. Thier whiskers were reputedly used as pipe cleaners.

It is believed that competion with fishermen, likely led to the extinction of the species.

In 2007, the South Korean Ministry of Environment announced a joint research initiative with North Korea, Russia and China to locate and bring back the species. The Korean Times reported that, "[i]f they manage to find one in these countries, then the government will bring some to the East Sea, but if not, it plans to bring some from the United States."

 

Further Reading 

  1. Zalophus japonicus Aurioles, D. & Trillmich, F., 2008, IUCN (accessed April 8, 2009)
  2. Zalophus, Seal Conservation Society (accessed April 8, 2009)
  3. The Pinnipeds: Seals, Sea Lions, and Walruses, Marianne Riedman, University of California Press, 1991 ISBN: 0520064984 
  4. Encyclopedia of Marine Mammals, Bernd Wursig, Academic Press, 2002 ISBN: 0125513402
  5. Marine Mammal Research: Conservation beyond Crisis, edited by John E. Reynolds III, William F. Perrin, Randall R. Reeves, Suzanne Montgomery and Timothy J. Ragen, Johns Hopkins University Press, 2005 ISBN: 0801882559
  6. Heath, C.B. (2002) California, Galapagos, and Japanese sea lions. In: Perrin, W.F., Wursig, B. and Thewissen, J.G.M. Eds. Encyclopedia of Marine Mammals. Academic Press, San Diego.
  7. Walker's Mammals of the World, Ronald M. Nowak, Johns Hopkins University Press, 1999 ISBN: 0801857899 
  8. California sea lion, MarineBio.org (accessed April 8, 2009)
  9. Extinct Sea Lions to Bring Back to Korea, Bae Ji-sook, The Korean Times, 2007 
  10. Galápagos and Californian sea lions are separate species: Genetic analysis of the genus Zalophus and its implications for conservation management, Wolf, JB; Tautz, D; Trillmich, F, Frontiers in zoology, 2007.
Glossary

Citation

Life, E. (2014). Japanese sea lion. Retrieved from http://www.eoearth.org/view/article/153946

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