Size-dependent, Spatial, and Temporal Variability of Juvenile Walleye Pollock (Theragra chalcogramma) Feeding at a Structural Front in the Southeast

• Main Authors: Bering Sea, Robert Schabetsberger, Marc Sztatecsny, Gabriele Drozdowski, Richard D. Brodeur, Gordon L. Swartzman, Matthew T. Wilson, Andreas G. Winter
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Theragra chalcogramma; walleye pollock; predation; diel feed- ing; frontal regions; Bering Sea; Copepods
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.612.7914; http://www.pmel.noaa.gov/foci/publications/2003/scha0474.pdf

Abstract. The waters surrounding the Pribilof Islands are an important nursery ground for juvenile walleye pollock (Theragra chalcogramma), an important forage fish in the pelagic food web of the productive Bering Sea shelf region. The diet of juvenile pollock was studied in two consecutive years along a transect line crossing from a well-mixed coastal domain, through a frontal region to stratified water farther offshore. Variability in stomach fullness was high and evidence for increased feeding intensity in the front was weak. Prey diversity and prey size generally increased with increasing fish size, shifting from predominantly small copepods to larger, more evasive prey items such as euphausiids, crab megalopae and fish. The diet of the fish reflected changes in the relative abundance of copepods and euphausiids in the prey fields between years. Juvenile pollock showed increased feeding rates at dusk, and stomach