Approximately 100 species of mammal are known to inhabit, or to have recently inhabited, the Korean Peninsula and its surrounding waters. This includes a few species that were introduced in the 20th century; the coypu was introduced for farming in the 1990s, and the muskrat was introduced in the early 20th century into the Russian Far East, and was subsequently first recorded in Korea in the Tumen River basin in 1965. The Siberian tiger is the national animal of South Korea. The Siberian tiger and Amur leopard have most likely been extirpated from Korea, but are still included in standard lists of Korean mammals. However, tigers and other large carnivores in Korea were hunted into extinction by the Japanese during the Japanese occupation.