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• Calanus , Metridia and Neocalanus copepods were sampled during pollock age-0 year. • Strong correlation between lipid-rich copepods and pollock abundance 3 years later. • Higher correlation to age-3 pollock with model than sample-based copepod indices. • Age-3 pollock indices significantly related to cold pool area (age-0 year). In the southeastern Bering Sea, years with above-average sea ice extent have been associated with elevated abundances of large lipid-rich copepods in both net tows and age-0 walleye pollock (Gaduschalcogrammus) diets, followed by high overwinter pollock survival and stronger recruitment into the fishery three years later. In this study, we directly compare large copepod abundances of taxa important in age-0 pollock diets (Calanus glacialis/marshallae , Metridia pacifica and Neocalanus spp.) to age-3 pollock abundance from stock assessments for year classes 2002–2015 (excluding 2013). Copepod samples from bongo nets were collected on fishery oceanography surveys in late summer during warm (low ice) and cold (high ice) climate stanzas. In addition to mean estimates of large copepods among stations (sample-based), we implemented a spatial delta-generalized linear mixed model using the Vector Autoregressive Spatio-Temporal (VAST) package to account for variations in survey coverage among years. Positive significant linear relationships were found for both of these estimates of large copepods during the age-0 year and the abundance of these pollock at age-3. Correlations were stronger using VAST model-based indices compared with sample-based indices (R 2 = 0.74 versus 0.43, respectively, all copepod taxa combined). A significant relationship was also observed between the bottom cold pool (< 2 °C) area (indicative of sea ice coverage in the prior winter) during the age-0 year and subsequent age-3 pollock abundance (R 2 = 0.56) and recruits per spawner, (ln(age-3 abundance /spawning stock biomass), R 2 = 0.77). Consequently, the large copepod index or cold pool index may be used to predict future recruitment success of pollock three years in advance. Results provide support for the revised oscillating control hypothesis that suggests as the climate warms, reductions in sea ice and consequent reduced availability of ice-associated algae, an early spring food source, could be detrimental to large copepods and recruitment of the pollock stock in the region. [ABSTRACT FROM AUTHOR]

Trophic levels of 1,105 humpback whales from six geographically and isotopically distinct North Pacific feeding groups were calculated using δ15N of humpback whales and regional primary consumers. The overall mean trophic level for North Pacific humpback whales was 3.6 ± 0.02, indicating a diet of both fish and zooplankton, and, thus, supporting assumptions of humpback whales as generalist predators. The highest mean trophic level was calculated for the north Gulf of Alaska group (4.0 ± 0.03), while the lowest was found for the Russian and the western Aleutian Islands group (3.3 ± 0.08). Differences in mean trophic levels suggest that feeding groups differ in the proportion of fish and zooplankton in their diets. [ABSTRACT FROM AUTHOR]