The First Molecular Evidence of Korean Zalophus japonicus (Otariidae: Sea Lions) from the Archaeological Site of Dokdo Island, Korea

Abstract

Zalophus japonicus (Japanese sea lion, family Otariidae) was a mammal that once flourished around Dokdo Island. Overharvesting of the Korean sea lion in the early and mid-20th century resulted in a drastic decline of individual numbers, and it is currently listed as an extinct species by the International Union for Conservation of Nature (IUCN). An attempt is made to analyze the DNA sequences of the Korean sea lion with Japanese samples and living sea lions in the context of modern biology. Bones of Z. japonicus were retrieved from the archaeological site in Dokdo Island, and DNA sequences of mitochondrial control region (Dloop) were isolated using molecular methods. The DNA sequences of Korean Z. japonicus showed a high sequence similarity (98–99%) but did not exactly match with those reported from bone samples of stuffed specimens of the Japanese Z. japonicus caught in Japanese territories. As expected, the mitochondrial sequence was clearly distinct from two other sea lions, Z. californianus and Z. wollebaeki (92–93%). This is the first molecular identification of the Korean Z. japonicus and could provide useful information for species identification and genetic diversity of Z. japonicus. We believe that this key reference can play a significant role in the recovery of natural populations of Z. japonicus.