Projected Spatial Distributions for Eastern Bering Sea Arrowtooth Flounder Under Simulated Climate Scenarios, with Implications for Predation

Empirical relationships between the extent of the eastern Bering Sea shelf summer “cold pool” (bottom water ≤ 2° C) and maximum sea ice extent and sea level pressure allow projections of cold pool area from global climate model simulations.  The present study uses these projections to predict future spatial distributions of arrowtooth flounder (Atheresthes sp.) in the Bering Sea assuming these distributions are controlled primarily by the cold pool.  An inverse relationship between the area occupied by arrowtooth flounder and the cold pool area has been observed from 1982-2010.  Small cold pool areas and large arrowtooth flounder areas were observed in the warm years of 2003-2005, whereas the colder years of 2006-2010 have exhibited larger cold pool areas and smaller arrowtooth flounder areas.  Projections of cold pool area from 2010 to 2050 based upon 15 International Panel on Climate Change (IPCC) model runs show a wide range of variability but an overall decreasing trend, resulting in the median arrowtooth flounder area across the 15 IPCC models increasing from 140,000 km² in 2010 to 160,000 km² in 2050.  Changes in the spatial distribution of arrowtooth flounder relative to other species can affect their consumption of prey, of which age 1 and 2 walleye pollock (Theragra chalcogramma) comprise a large portion.  The relationship between the area occupied within various EBS sub-areas and cold pool extent will be examined for arrowtooth flounder and walleye pollock in order to project future spatial distributions and assess the potential impact of arrowtooth predation on pollock.