Feeding of Walleye Pollock Gadus chalcogrammus (Gadidae) in the Epipelagic Zone of the Bering Sea

Abstract

From 1982–1990 to 2006–2010 in the western part of the Bering Sea biomass of the walleye pollock Gadus chalcogrammus decreased by almost an order of magnitude, from 7.2 to 0.7 million tons. However, in the last decade (2011–2020) its biomass increased to the long-term average value (4.0 million tons). In the eastern part of the sea, the pollock biomass dynamics was of the wave-like nature with the highest value in 1982–1990 and the lowest, in 2006–2010. The food spectrum of the walleye pollock is wide and includes 16 taxonomic groups of aquatic organisms. The main part of average annual food mass consumed by pollock in the Bering Sea in 1982–2020 consisted of zooplankton (74.1%). During different study periods, annual feed consumption varied from 91.1 to 373.0 (average 239.3) million tons per year. Significant fluctuations in the volume of food consumed are mainly associated with the dynamics of the species’ biomass.