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Not Japanese after all: Tsushima otter deemed to be Eurasian river otter

The video captured of the otter on Tsushima island, Nagasaki Prefecture, is shown at a press conference at the Ministry of the Environment on Aug. 17, 2017. (Mainichi)

The first wild river otter to be spotted in 38 years on Tsushima island, Nagasaki Prefecture, is thought to be a close relative of a Eurasian river otter -- not a Japanese river otter, the Ministry of the Environment announced on Oct. 12.

The results came from a government survey carried out on the island from August to September, which did not locate any of the animals, but was able to find new excrement samples. DNA analysis of those samples revealed that at least one male Eurasian river otter, common on the Korean Peninsula and Russia's Sakhalin Island, lived on Tsushima island.

"The samples showed a different ancestral background than the Japanese river otter," said Chikushi Jogakuen University professor of animal ecology Hiroshi Sasaki, who led the survey. While the now-extinct Japanese river otter was once prevalent all over Japan, Sasaki suggested the possibility that Eurasian river otters crossed the ocean to Tsushima from South Korea.

This provided photo taken Aug. 31, 2017, shows what is thought to be otter excrement, on Tsushima island, Nagasaki Prefecture. (Photo courtesy of the Ministry of the Environment)

The otter was first spotted on the island on footage from a camera set up by a research group from the Animal Ecology Laboratory at the University of the Ryukyus in Okinawa Prefecture. Following the confirmation of the animal, the environment ministry carried out a population survey on the island.

The investigation discovered four new excrement samples along the coast and near a river, as well as what appeared to be otter footprints. The total number of otters on the island could not be determined, and the ministry will reportedly continue testing.

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