Findings on American Shad and Striped Bass in the Hudson River Estuary: A Fish Community Study of the Long-Term Effects of Local Hydrology and Regional Climate Change

It has been hypothesized that climate change is an underlying factor in determining fish abundances in the Hudson River estuary (HRE). To study the effects of hydrology and climate on the HRE fish community, we applied multivariate statistical methods to data on 20 species—life history stages collected from 1974 to 2005. We confirm that the HRE fish community has changed over this period. These changes are correlated with local hydrology (freshwater flow and water temperature) and regional climate (the Atlantic Multidecadal Oscillation [AMO] and North Atlantic Oscillation). We found that the abundances of striped bass Morone saxatilis larval stages are positively correlated with high freshwater flows and those of juvenile American shad Alosa sapidissima negatively correlated with the AMO or warmer sea surface temperatures. Our findings suggest that climate-related variability affects HRE juvenile shad abundances and that management strategies for this declining species should include the implications of climate change.