Assessing the status or population size of species is a key task for wildlife conservation and the sustainable management of harvested species. In particular, assessing historical changes in population size provides an evolutionary perspective on current population dynamics. Japanese eel (Anguilla japonica) is an endangered yet commercially important catadromous fish species. This article assesses the demographic history of Japanese eel using the pairwise and multiple sequentially Markovian coalescent methods. The analyses indicate a reduction in effective population size Ne from 38,000 to 10,000 individuals between 4 and 1 Mya, followed by an increase to 80,000 individuals between 1 Mya and 22--30 kya. Approximately 22--30 kya there is evidence for a reduction in Ne to approximately 60,000 individuals. These events may be related to changes in environmental conditions, especially around the last glacial maximum (19--33 kya). The results of this study suggest that Japanese eel has experienced at least two population bottlenecks, interspersed by a period of population growth. The overall level of genetic diversity is relatively low, although there is no evidence for inbreeding. Data from this study will be used to help model the extinction risk of Japanese eel.
Key Words: climate change, last glacial maximum, pairwise and multiple sequentially Markovian coalescent, whole-genome sequence