Abstract
Three landlocked populations of an amphidromous goby, Rhinogobius sp.CO, in San-nome-gata Lake, Akita Pref., Ukinuno Pond, Shimane Pref., and Cheonmi River, Jeju Island, Korea, were identified and evidenced by allozyme and otolith analyses. Line analysis of strontium: calcium ratios along the life history transect of their otoliths showed relatively stable values as compared to those of amphidromous conspesifics, indicating the absence of sea-going career. The San-nome-gata and Ukinuno populations would have been landlocked in the Jomon (6000 years ago) and the Hakuho (1300 years ago) periods, respectively. Landlocking of the Cheonmi population may have occurred occasionally.
