Identification of individuals and kinship using Eurasian otter fecal DNA from the Naeseongcheon stream

Naeseongcheon stream flows through Bonghwa-gun and Yecheon-gun in Gyeongbuk, South Korea. This study investigated otter genetic diversity using noninvasively collected fecal samples to determine population, sex, and kinship. In April 2019, 20 otter fecal samples were collected from a 60 km stretch of the stream for DNA extraction. Of these, DNA was extracted only from 12 relatively fresh samples to identify individuals and perform sex determination experiments. The results of genotyping, performed using seven microsatellite markers, estimated that at least 11 individual otters lived in Naeseongcheon stream. In addition, genetic analysis for sex determination found six females and five males. Based on the analysis of the kinship between individuals, it was determined that Gyeongjin A (GjA) and Gyeongjin B (GjB) were likely to be siblings with Musum A (MsA) as their father (GjA/MsA-QGM: 0.411, GjB/MsA-QGM: 0.700, and GjA/GjB-QGM: 0.806). Seokgwan C (SgC) was likely an offspring of Seokgwan B (SgB, male) and Seokgwan A (SgA, female; SgC/SgA-QGM: 0.652, SgC/SgB-QGM: 0.525). The methods used in this molecular genetic study are appropriate for continuously monitoring otters living in large areas. Expanding the target area to adjacent water systems including Nakdonggang river would be highly helpful in conserving endangered wildlife species.