It is said that in the mid of the 19th century the population of the Japanese sea lions counted about 30.000-50.000 animals. Harvest records by commercial fishermen show that in the early 1900s about 3.200 Japanese sea lions were killed per year, but already in 1915 the harvest declined to only 300 sea lions. The number still declined to a dozen of sea lions at the 1930ies. In the 1940ies the commercial hunting on Japanese sea lions ended, because the species became almost extinct. In total, the Japanese hunted commercially 16.500 Japanese sea lions. A further factor can be also the marine warfare of World War II which probably contributed to the destruction of the sea lions’ habitat.

Instead of several intensive search expedition to their former habitats, the Japanese sea lion could never been observed again since the late 1950ies. Last reports were given about 50-60 Japanese sea lions on the Liancourt Rocks, a small island group in the Japanese Sea just between Honshu and South Korea.

Stuffed specimen of Japanese sea lion (Click to view larger image).

There were still some sightings of single Japanese sea lions in the 1970ies, the last one in 1974 in northern Hokkaido. But it is not clear, if these animals are indeed Japanese sea lions or escaped Californian sea lions. At the first glimpse such a mistake seems to be astonishing, but scientists regarded for a very long time the Japanese sea lion as a subspecies of the Californian sea lion. Only after the extinction of the Japanese sea lion, modern researches in 2003 could show that the Japanese sea lion has to be separated from the Californian sea lion (Zalophus californianus ) and has to be registered as a special species Zalophus japonicus . The Japanese sea lion has a larger and a much broader skull than the Californian species and is in general slightly larger than the Californian species. Furthermore, the Japanese sea lion have six teeth behind their upper canine tooth, but the Californian sea lion only five. Later on, a gene analysis testified the difference of both species too.

Male Japanese sea lions were dark grey-brown, reaching lengths of 2.3 to 2.5 m and a weight of about 450 to 560 kg. Old males had an almost black fur. Compared with the males the females were significantly smaller reaching lengths of 1.40 to 1.64 m and had a lighter color too. In former times Japanese sea lions were popular animals in Japanese zoos like in the Tennoji Zoo in Osaka, which has still 3-4 stuffed animals in its collection. But today only stuffed animals can be found in this zoo and some other places in Japan. Also the Natural History Museum in Leiden, Netherlands, possesses a stuffed Japanese sea lion which was sent to Leiden by Philipp Franz von Siebold during his stay on Dejima Island near to Nagasaki. Because even stuffed Japanese sea lions are seldom to be seen today, we are extremely happy to exhibit this rare and interesting species in our LOST ZOO as the first new arrival in 2016.

Executive Curator
JURGEN LANGE