ИСТИНА

Summarizing the results of the Pacific cod studies, a generalized scheme of the organization of Pacific cod population might be presented. There exists a central grouping, which can be traced back to ancestral forms, which colonized the North Pacific from the Arctic after the Bering Strait opened 5.4-5.5 million years ago (according to updated data). This subunit combines the modern population of Pacific cod from deep-sea Okhotsk and Bering Seas, Gulf of Alaska and coastal waters of the Pacific, living at stable temperature and salinity conditions, exposed to relatively weak changes, even during periods of global glaciation maxima and accompanying oceanic regressions. Some internal differentiation can be determined by the power of gene flow between different parts of the range, which are under the effect of various factors from the water current systems to the biological characteristics of individual stocks.