Diagnosing the Effects of Climate Variability on the Northeast US Continental Shelf Summer Flounder Biomass

Temperature is an important factor influencing biological processes. To diagnose the effects of climate variability on summer flounder (Paralichthys dentatus), an important commercial fish on the Northeast US Continental Shelf, two questions need to be answered: how large-scale atmospheric and oceanic forcing influences seawater temperature on the Shelf, and how summer flounder on the Shelf reacts to inter-annual seawater temperature variability. For the first question, Empirical Orthogonal Function (EOF) analysis was used to extract the leading mode of variability in SST and BT, using data from Extended Reconstructed SST and Northeast Fisheries Science Center oceanographic data. Using cross-correlation analysis between the leading modes and several climate indices then, SST and BT were found to be correlated significantly by the position of the Gulf Stream, ENSO, and especially NAO. Canonical Correlation Analysis (CCA) was used to correlate the spatial patterns in SST and BT with summer flounder biomass, to answer the second question. Significant spatial correlation patterns were found in CCA between SST/BT and summer flounder biomass, indicating that seawater temperature plays an important role in determining summer flounder biomass on the Shelf. Finally, a clear cause-effect logic chain was built between climate variability and summer flounder biomass on the Shelf.