◆Associate Professor Koji Uda of the Department of Natural Sciences and Engineering presented on otter habitats at the 76th Annual Meeting of the Chugoku-Shikoku Branch of the Zoological Society of Japan.
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Otter presence confirmed on Tsushima for the first time in about five years
— Evidence Suggests Otters May Be Breeding on Tsushima —
In 2017, a wild otter was photographed on Tsushima Island in Nagasaki Prefecture, attracting significant attention as the first confirmed sighting of the species in Japan in approximately 40 years. In 2018, its survival was scientifically confirmed through DNA analysis of feces, but no clear evidence supporting its continued existence has been obtained since then.
A research group led by Associate Professor Koji Uda of the Department of Science and Engineering has analyzed feces believed to be from an otter, collected on Tsushima in February 2024, and sequenced the entire mitochondrial DNA.The results revealed that this individual is genetically very closely related to the Eurasian otter found in South Korea and belongs to the same lineage as the population confirmed in 2017–2018. This not only confirms the presence of otters on Tsushima for the first time in about five years but also suggests that the individuals confirmed previously may have been breeding on the island.
The findings of this study provide important insights for assessing the potential for the continued presence and establishment of otters on Tsushima, and serve as a scientific foundation for future conservation strategies and discussions regarding reintroduction.
These findings were presented at the 76th Annual Meeting of the Chugoku-Shikoku Branch of the Zoological Society of Japan, held on May 17, 2025, in Matsuyama City, Ehime Prefecture.