Animal Database

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Animal Database
Animal Database
Japanese River Otter
220px-Japanese otter
Range Seto Inland Sea, and in the Uwa Sea in 1972 and 1973.
Scientific Classification
Kingdom Animalia
Phylum Chordata
Class Mammalia
Order Carnivora
Family Mustelidae
Genus Lutra
Species L. lutra
Conservation Status

The Japanese River Otter (Lutra lutra whiteleyi) is an extinct variety of otter formerly widespread in Japan. Dating back to the 1880s, it was even seen in Tokyo. The population suddenly shrank in the 1930s, and the mammal nearly vanished. Since then, it has only been spotted several times, in 1964 in the Seto Inland Sea, and in the Uwa Sea in 1972 and 1973. The last official sighting of one was in the southern part of Kochi Prefecture in 1979, when it was photographed in the mouth of the Shinjo River in Susaki. It was subsequently classified as a "Critically Endangered" species on the Japanese Red List, On 28 August 2012, the Japanese river otter was officially declared extinct by the Ministry of the Environment. On January 10, 2013, dozens of eyewitnesses reported seeing them in Aichi Prefecture.

It is the official animal symbol of Ehime Prefecture.



Fully grown, a Japanese otter was between 65 and 80 cm (25–31 in) long, with a tail measuring 45 to 50 cm (17 to 20 in). It had a thick, lush coat of dark brown fur with short webbed feet.

Ecology and biology[]


A nocturnal creature, an otter only left its den after dark to forage for food. Claiming a territory about ten miles in diameter, it marked the area with its droppings about one to three miles apart and sets up three or four nests under rocks or inside bushes. The otters were always on the move, visiting each den only once every three to four days.


Pic 006

Lutra nippon catches its main meal, fish.

Like most otters, the Japanese river otter was not an especially picky eater. While it primarily fed on fish, crab, and shrimp; it also ate eels, beetles, watermelons, and sweet potatoes.

Cause of extinction[]

In the past, there were thousands of river otters in Japan. Starting in the Meiji period, the government of Japan adopted a policy of increasing wealth and military prowess. Animal pelts thus became very valuable since they could be exported for money. As a result, Japanese river otters started to be hunted and killed throughout the country. Their population soon went down. Even so, pollution and human development then harmed their environment and resources to build their habitats. This pollution terminated their food sources in the rivers, causing them to hunt in more dangerous settings. These causes grew rapidly, resulting in the extinction of the Japanese river otter in the late 20th century.

Efforts to prove its Existence[]

Throughout the 1990s, there were several attempts to locate a surviving Japanese river otter.

In December 1991, the Environmental Agency of Japan in partnership with the Kochi prefectural government assembled a research team of experts and began their search. In March 1992, the research group found hair and excrement in Kochi Prefecture and believed to have come from an otter. Also found were three footprints, and ten additional excrement samples. After an analysis of a cross-section of the hair, the researchers determined that it came from an otter. An official from the agency's wildlife protection section stated that the hair was "scientifically solid evidence that confirms the existence of the Japanese Otter."

In 1994, zoological experts visited the area where the excrement was found. They discovered remains of the animal's urine, which the animal is believed to leave during its courtship. The prefectural government of Kochi set up an infrared camera for six months from October 1994 to April 1995 in an effort to capture it on film, but all that was recorded were animals such as raccoon dogs.

Between 4 and 9 March 1996, a group of zoo officials, municipal government officials and animals lovers from across the country searched for the river otter in the areas where finds have been made in the past. Such areas included coastal areas in Susaki, areas along the Niyodo River running through Sakawacho and Inocho, and coastal areas along Shimanto River. No evidence of the animal's existence was found.