Migrants in Far Eastern Seas of Russia
Appearance of different sea habitants (fishes, reptiles, mammalia) in Far Eastern seas of Russia migrating from southern and northern latitudes and eastern part of the Pacific Ocean in XX-XXI centuries is discussed, based on literature data and on results of long-term personal observations. Some species are known only on single or rare findings while other appeared rather regularly, sometimes in huge number. Main reasons of the shift of geographical distribution of heat-loving species in the northern direction are supposed to be the climatic factor and periodic outbreaks of number of the comparatively small pelagic fishes of the subtropical complex (Japanese sardine, eastern mackerel et al.) and migrations to the north of whales, sharks and the other predatory representatives of ichthyophauna that feed on them. In summer period heat- loving fishes migrate to the north up to the western part of the Bering Sea exclusively from south, whereas eastern Pacific representatives of ichthyofauna can penetrate there by two ways: adult individuals migrate mostly from the north of the Bering Sea moving to the south along the coast of Kamchatka, while spawn and juveniles - from east along Aleutian Islands due to Aleutian sea current. Two representatives of the northern migrants (Arctic cod and narwhal) periodically penetrate in south-western part of the Bering Sea from its regions adjacent to the Bering Strait and Chuckchee Sea. During outbreaks of its number (the most powerful of it were registered in 1969 and 1979) Arctic cod was an object of russian trawl fishery. Unlike Arctic cod, narwhals penetrate out of limits of polar waters extremely rare and only in winter.