Population Structure of Finless Porpoise (Neophocaena phocaenoides) Discovered off Coastal Waters, Republic of Korea

The finless porpoise (Neophocaena phocaenoides Cuvier, 1829) is distributed in the coastal waters of Asia, throughout Indonesia to the east, and as far north as the Taiwan Strait. The finless porpoise has been declared critically endangered by the WWF (World Wide Fund for Nature), and in 2017 was rated vulnerable on the IUCN Red Threatened Species List. Since this species is distributed near the coast and has many interactions with humans, effective conservation of the species requires further studies into their genetic diversity and population. In this study, 45 samples were obtained from bycatch or stranded individuals in the East, South, and West Seas, where Korean porpoises were mainly distributed from 2017-2021. We compared 473 bp mtDNA sequences from the control region. Pairwise fixation indices (F-ST) revealed that the two populations differed significantly (F-ST = 0.4557, p = 0.000). In contrast to high levels of genetic differentiation, gene flow was identified as medium levels (Nm of 0.04-0.71). Our data suggest that finless porpoises may have undergone a historic differentiation event, and that finless porpoises in the three regions could be divided into two populations: West and East/South.