Alternating temperature states influence walleye pollock early life stages in the southeastern Bering Sea

Abstract

Water temperatures in the southeastern Bering Sea influence the density of walleye pollock Theragra chalcogramma early life stages, potentially influencing spatial distributions and the phenology of reproduction and development. We quantified stage-specific changes in spatial and temporal distributions under cold- and warm-water conditions using generalized additive models. Analyses showed that walleye pollock egg and yolksac larval spatial distributions are unaffected by temperature, suggesting that spawning locations are stable. Preflexion larvae, late larvae, and juveniles shift onto the shelf under warm conditions, similar to spatial shifts observed in distributions of sub-adults and adults. Temporal distributions were used to address the hypo - thesis that timing of the density peak at each stage is delayed under cold conditions. Differences in the timing of density peaks supported the hypothesis that the timing of spawning, hatching, lar- val development, and juvenile transition are temperature-dependent. The current analysis repre- sents the best support available for the importance of temperature to walleye pollock in determin- ing early life stage development and population trends in the eastern Bering Sea. Our data indicate that future changes in water temperatures could influence the early life stages of an eco- logically dominant member of the Bering Sea community by changing phenology and habitat use in the first several months of life.