On relationships between cannibalism, climate variability, physical transport, and recruitment success of Bering Sea walleye pollock (Theragra chalcogramma)

Walleye pollock (Theragra chalcogramma) is the single most abundant fish sp ecies in the Bering Sea and comprises the bulk of the commercial catch. Juv enile pollock are an important forage fish for older pollock, other fish, m arine mammals, and birds. We examine the interaction between cannibalism, c limate variability, and related patterns in physical transport. Our analysi s of adult and juvenile pollock abundance and distribution time series, oce an current modelling studies, and information on climate variability indica tes that cannibalism is a major determinant of interannual recruitment vari ability. In turn, the intensity of cannibalism appears to be dependent on t he degree of spatial separation of adults and juveniles. Strong year classe s occur when juvenile pollock are transported inshore and away from adults in spring - conditions typical of warm years. In cold years, transport is r educed and juveniles remain on the outer shelf in proximity to adults. Go-o ccurring distribution patterns of adults and juveniles resulting from these conditions lead to potentially increased cannibalism and subsequent weak y ear classes. (C) 2000 International Council for the Exploration of the Sea.