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Webinar: Climate oscillations, the Cold Pool, and walleye pollock recruitment in the Bering Sea: lessons from recent years and the outlook for 2018
Monday, 29 January 2018, 12:00
Monday, January 29, 2018. 12:00PM. Webinar: Climate oscillations, the Cold Pool, and walleye pollock recruitment in the Bering Sea: lessons from recent years and the outlook for 2018. Janet Duffy-Anderson, NOAA/Alaska Fisheries Science Center. Sponsored by Center for Satellite Research and Applications. More information here.
The southeastern Bering Sea shelf experienced unprecedented warming from 2014-2016. Ecosystem observations from this most recent warm stanza included sea surface temperatures as high as 15oC, the presence of coccolithophore blooms, reduced abundances of lipid-rich copepods, and an eastward shifted distribution of young-of-the-year (YOY) walleye pollock (Gadus chalcogrammus) with moderately low energetic content. These observations indicated that YOY walleye pollock would experience increased susceptibility to over-winter mortality and catastrophic population declines up to 40% were feared. Despite these warning signs, significant declines in the pollock population did not occur. Evidence from ecosystem surveys indicated that warming in 2015, the second year of the three-year stanza, was atypical relative to prior warm stanzas and offered an avenue for fish refuging from deleterious warm ecosystem conditions. We propose a new hypothesis, the Cold Pool Refuge Hypothesis, to explain these events and we present evidence to support the idea. The Bering Sea has recently entered a cooler period, with spring 2017 sea ice covering much of the southern shelf and into Bristol Bay and cooler conditions observed over the summer. We evaluate ecosystem conditions in 2017 relative to the 2014-2016 warm stanza and provide an outlook for walleye pollock survival and recruitment success in 2018 and beyond.