Japanese sea lion
The Japanese sea lion was an aquatic mammal that became extinct in the 1970s. It was considered to be a subspecies of the related California sea lion until 2003. They inhabited the western North Pacific and its marginal seas including the Sea of Okhotsk and the Sea of Japan, especially around the coastal areas of the Japanese Archipelago and the Korean Peninsula. They generally bred on sandy beaches which were open and flat, but sometimes in rocky areas. They were hunted commercially in the 1900s, leading to their extinction.
Taxonomy
Prior to 2003, it was considered to be a subspecies of California sea lion as Zalophus californianus japonicus. However, it was subsequently reclassified as a separate species. DNA analysis in 2007 estimated that the divergence point between the two sea lions took place around 2 million years ago in the early Pleistocene.Several taxidermied specimens can be found in Japan and in the National Museum of Natural History, Leiden, the Netherlands, bought by Philipp Franz von Siebold. The British Museum possesses a pelt and four skull specimens.
Description
Male Japanese sea lions were dark grey, reaching lengths of and weighed about. Females were significantly smaller at long and weighed about with a lighter grey colour than the males.Distribution and habitat
Japanese sea lions were found along the northwest Pacific coastline, specifically in Japan, Korea, southern Kamchatka Peninsula, and the Sakhalin Island. However, they may not have existed in Kamchatka, with their northernmost range extending only to the Kuril Islands. Sightings of individual Japanese sea lions still persist in Korea, but these are probably misidentified Steller's sea lions. The only reliable report from Kamchatka may have been of a single individual shot at Moneron Island in 1949.Old Korean accounts also describe that the sea lion and spotted seal were found in a broad area containing the BoHai Sea, the Yellow Sea, and the Sea of Japan. Many places along the Japanese coastline are named after sea lions or seals, such as Ashika-iwa, Ashika-jima, and Cape Inubō. Bones of Z. japonicus dating to 3500–2000 BC were found in the Shell Mound in Dongsam-dong, Busan. Genetic evidence confirms the former presence of Z. japonicus on the Liancourt rocks.
They usually resided on flat, open, and sandy beaches, but rarely in rocky areas. Their preference was to rest in caves.
Exploitation and extinction
Many bones of the Japanese sea lion have been excavated from shell middens from the Jōmon period in Japan. An 18th-century encyclopedia, Wakan Sansai Zue, describes that the meat was not tasty and they were only used to render oil for oil lamps. Valuable oil was extracted from the skin, its internal organs were used to make expensive medicine, and its whiskers and skin were used as pipe cleaners and leather goods, respectively. At the turn of the 20th century, they were captured for use in circuses.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 a few dozen sea lions by the 1930s. Japanese 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. Submarine warfare during World War II is also believed to have contributed to their habitat destruction. The last population survey dates from the 1950s and reported a population of only 50 to 60 animals on the Liancourt Rocks. The most recent sightings of Z. japonicus are from the 1970s, with the last confirmed record being a juvenile specimen captured in 1974 off the coast of Rebun Island, northern Hokkaido. There were a few unconfirmed sightings in 1983 and 1985. In any case, it was one of the most recent marine mammal extinctions to occur, alongside the Caribbean monk seal which went extinct at around the same time.