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 hypothesis 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, larval development, and juvenile transition are temperature-dependent. The current analysis represents the best support available for the importance of temperature to walleye pollock in determining 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 ecologically dominant member of the Bering Sea community by changing phenology and habitat use in the first several months of life.KEY WORDS: Theragra chalcogramma · Temperature · Distribution · Phenology · Bering Sea Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 455: [257][258][259][260][261][262][263][264][265][266][267] 2012 temperature during the pollock post-spawning feeding season (Kotwicki et al. 2005). Biomass increased with summer temperatures and the feeding migration progressed farther north and inshore (east) from spawning grounds as temperature increased. Kotwicki et al. (2005) hypothesized that warmer water temperatures advance the post-spawning feeding migration by advancing the timing of spawning. They did not address the alternate hypothesis that spawning distribution changes in response to temperature conditions.Colder than average years are characterized by late sea-ice retreat from the shelf in the spring, water column temperatures < 2°C over the shelf during spring and summer, and abundant large-bodied zooplankton . Warmer than average years are characterized by early ice retreat, continental shelf water temperatures > 2°C during spring and summer, and smallbodied zooplankton. Sea-ice conditions also determine the extent and location of a pool of cold bottom water in the summer over the middle shelf (50 to 100 m depth, Stabeno et al. 2012a). Pollock distributions generally are restricted to areas > 2°C, such as those found outside the cold pool (Wyllie-Echeverria & Wooster 1998). Therefore, in warm years, a larger area of thermally-suitable habitat is available to pollock over the continental shelf, particularly over the midd...

Factors affecting summer distributions of Bering Sea forage fish species: Assessing competing hypotheses

“…Our average model results for water column age-0 pollock suggested that age-0 pollock densities were highest close to the mean location of preflexion larvae in late-spring and early-summer as reported by Smart et al (2012). This pattern infers that passive advection and diffusion of eggs and larvae are consistent with patterns observed in other studies (Hinckley et al, 1991;Brodeur and Wilson, 1996).…”

“…As all early life stage (egg, yolksac larvae, late-larvae, and juveniles) cold-year loci were highly correlated (>0.95), the preflexion stage was selected based on consultation with Smart et al (2012) coauthors. Mean early life stage locations were not available for capelin or age-0 Pacific cod.…”

“…13 Distance from the center of each EDSU to the mean location of pollock preflexion larvae captured in cold years (Smart et al, 2012) (Preflex) was used as a variable in this analysis. As all early life stage (egg, yolksac larvae, late-larvae, and juveniles) cold-year loci were highly correlated (>0.95), the preflexion stage was selected based on consultation with Smart et al (2012) coauthors.…”

Effects of climate and demography on reproductive phenology of a harvested marine fish population

“…This study presents the first comprehensive analysis of variable spawning phenology for pollock. Previous studies focused in the Bering Sea have suggested that pollock spawn timing may be sensitive to temperature (Haynie & Pfeiffer, 2013;Smart, Duffy-Anderson, & Horne, 2012) and documented geographic variation in spawn timing among spawning groups experiencing different thermal regimes (Bacheler, Ciannelli, Bailey, & Duffy-Anderson, 2010;Jung, Kang, Kim, & Kendall, 2006), but the degree and form of thermal sensitivity was not quantified, and other (e.g., demographic) effects were not considered. In the Gulf of Alaska, some evidence for variation in spawn timing among years has been presented (Ciannelli, Bailey, Chan, & Stenseth, 2007;Yoklavich & Bailey, 1990); however, consideration of mechanisms has fallen outside the scope of previous studies.…”

Chum salmon (Oncorhynchus keta) growth and temperature indices as indicators of the year–class strength of age‐1 walleye pollock (Gadus chalcogrammus) in the eastern Bering Sea

“…Variations in pollock recruitment in the EBS were also linked to other life stages and oceanic conditions. For example, for the period of 1988–2008, age‐0 pollock were more abundant in warm years (Smart et al ., ). Also, there was a positive effect of temperature on the abundance of eggs, yolk‐sac larvae and preflexion larvae for intermediate temperatures; and positive effects on the abundances of late larvae and juveniles at high and low SSTs (Smart et al ., ).…”