Long-term increases in young-of-the-year growth of Arctic cisco Coregonus autumnalis and environmental influences

Arctic cisco Coregonus autumnalis young‐of‐year (YOY) growth was used as a proxy to examine the long‐term response of a high‐latitude fish population to changing climate from 1978 to 2004. YOY growth increased over time (r² = 0·29) and was correlated with monthly averages of the Arctic oscillation index, air temperature, east wind speed, sea‐ice concentration and river discharge with and without time lags. Overall, the most prevalent correlates to YOY growth were sea‐ice concentration lagged 1 year (significant correlations in 7 months; r² = 0·14–0·31) and Mackenzie River discharge lagged 2 years (significant correlations in 8 months; r² = 0·13–0·50). The results suggest that decreased sea‐ice concentrations and increased river discharge fuel primary production and that life cycles of prey species linking increased primary production to fish growth are responsible for the time lag. Oceanographic studies also suggest that sea ice concentration and fluvial inputs from the Mackenzie River are key factors influencing productivity in the Beaufort Sea. Future research should assess the possible mechanism relating sea ice concentration and river discharge to productivity at upper trophic levels.