Demography of a nearshore gadid navaga, Eleginus nawaga, from the Barents Sea coast during the last glacial period

Recent glaciations in northwestern Russia completely covered the Barents Sea during four glacial advances. At the peaks of those glacial advances, there were no nearshore macrofauna. Consequently, colonization by species that now inhabit present-day nearshore waters must have occurred since the habitat became available and hospitable, less than 15 thousand years ago (ka). We analyzed microsatellite data from navaga, Eleginus nawaga (Gadiformes: Gadidae), collected from Khaipudyrskaya Bay in the southeastern Barents Sea with coalescent-based models to estimate the times and effective population sizes that existed before and after major historical demographic changes. Colonization of E. nawaga , which could only follow establishment of a lower trophic-level food web, provides an indicator of that timing. The results of the analyses were consistent with two major demographic events. After an initial founding event before ~ 144 ka, the population grew to an effective size of about 2700 individuals. Subsequently, as the ice receded after the Last Glacial Maximum, it probably plateaued at ~ 26,000 about 3000 years ago. Colonization likely came from eastern populations following the Saalian Period, after which there was little nearshore ice to the East of the Kara Sea.