Population Structure and Microevolution of Pacific Cod Gadus macrocephalus Based on the Analysis of the Control Region (mtDNA) Polymorphism

We performed a population genetic analysis of 22 Pacific cod sample sets (n = 986) based on the mtDNA control region (599 bp) polymorphism, which made it possible to specify four distinguished groups of this species: (1) within the seaward parts of the Bering Sea and Sea of Okhotsk and northern part of the Pacific Ocean, affected by the Pacific Ocean gyres; (2) coastal areas of the East/Japan Sea; (3) northern part of the Sea of Okhotsk, more similar to the second group from the East/Japan Sea by haplotype sets than to the seaward groups, despite limited reproductive contacts, special hydrological conditions, and the history of formation of the sea areas; (4) fundamentally different Pacific cod from the Yellow Sea adapted to the conditions of the shallow water area in the subtropical region.