Climate-driven synchrony in otolith growth-increment chronologies for three Bering Sea flatfish species

Dendrochronology (tree-ring science) techniques were applied to otolith growth increments in 3 flatfish species collected from the eastern Bering Sea: northern rock sole Lepidopsetta polyxystra, yellowfin sole Limanda aspera, and Alaska plaice Pleuronectes quadrituberculatus. Within each species, otoliths were visually crossdated to ensure that the correct calendar year was assigned to each growth increment. Growth-increment widths were measured in each otolith, crossdating was statistically checked, and a single master chronology was generated for each species by averaging measurement time series after age-related growth declines had been removed. The 3 final chronologies spanned 18 to 20 yr and were significantly correlated with each other (p < 0.001), indicating a high level of growth synchrony among species. Final chronologies were compared to annual and monthly climate variables including water temperature, ice cover, the Pacific Decadal Oscillation, and the El Niño Southern Oscillation. Of the climate indices examined, chronologies were most strongly related to summertime eastern Bering Sea bottom temperatures, with R2 values of 0.81, 0.61, and 0.34 for the yellowfin sole, Alaska plaice, and northern rock sole chronologies, respectively. Chronologies were significantly (p < 0.01) and positively related to monthly resolved records of sea surface temperature, though the seasons of the year exhibiting the strongest correlations varied among species. The present study suggests that flatfish growth is strongly influenced by the temperature of the eastern Bering Sea, underscoring the effect of climate on fisheries in a highlatitude ecosystem.