Otters Return to Seoul’s Han River After Decades, With Five Families Spotted

Eurasian otters are quietly reclaiming Seoul’s Han River. A new DNA survey found 27 of the endangered animals along the river and its tributaries, nearly twice the 15 identified in a 2022 survey.

The National Institute of Biological Resources made the count by analysing DNA from 106 faecal samples collected at 27 sites between January and April. Twenty-one otters were found in the main channel and six in tributaries, with most concentrated in eastern Seoul. The survey identified 16 females and 11 males, and genetic analysis showed that all 27 were related. Researchers identified five parent-offspring family groups.

Five otters were found around Seongnae Stream in Songpa-gu. Three each appeared near Jamsil Bridge, Yangjae Stream in Gangnam-gu and Jungnang Stream in northeastern Seoul. Four were also identified near Hangang Bridge.

The species once lived commonly along the Han River but declined sharply because of hunting, water pollution and the loss of natural habitat. Concrete embankments and the construction of Paldang Dam further disrupted the river’s aquatic ecosystem. An otter carcass found near Olympic Bridge in 1986 became the last recorded trace in the Seoul section for three decades.

Sightings resumed in 2016, when an otter was filmed in Tancheon Stream. A family of four was recorded near Gwangjin Bridge the following year. Researchers attribute the broader return to improved water quality, recovering fish populations and efforts to restore natural riverbanks. Seoul began replacing concrete embankments with soil, gravel and vegetation about 20 years ago, and aims to finish the targeted sections by 2028.