Why does the pollock (<i>Theragra chalcogramma</i>) abundance change

Abstract

Some common ideas about environmental factors that determine the patterns of migration (including timing) and stock dynamics of walleye pollock are critically analyzed with particular attention to the Bering Sea. There is shown that the conception of the migration timing dependence on food supply in the northern Bering Sea does not represent the real facts, as well as the conception of year-class strength dependence on winter mortality of fingerlings determined by food supply, especially in conditions of its deficiency. Periodicity of the pollock stocks dynamics associated with global changes of climatic and oceanographic factors is also called in question. Role of provincial factors in dynamics of the pollock populations is discussed and emphasized.

Keywords

• pollock
• migration
• food deficiency
• year-class strength
• state of stock