Temporal Trends in Forage Fish Availability and Predation in the Northwest Atlantic with Ties to Climate Change

Climatic oscillations drive oceanographic processes; thus ecosystems and their trophic interactions can be altered by these large-scale forces.  Forage fish shape critical pathways within continental shelf food webs, linking upper and lower trophic levels.  In the northwest Atlantic, Atlantic Herring (Clupea harengus) and Atlantic Mackerel (Scomber scombrus) are two forage species which fulfill this important trophic role.  We examined temporal trends in forage fish abundance per tow and their consumption by 13 fishes for the northeast U.S. continental shelf with trends in the Atlantic Multidecadal Oscillation (AMO) and North Atlantic Oscillation from 1977-2012.  The hypothesis being that forage fish availability and their food web interactions are influenced by climatic oscillations.  Forage abundance and their consumption on the shelf cycled low in the late 1970s to early 1990s, and higher thereafter.  Interestingly, positive correlations between the forage series and most notably the AMO were observed for this region.  Modeling multivariate forage consumption, the inclusion of AMO did not radically improve model fit; however, other trophic relationships may have limited the utility of this covariate for some species (e.g. cannibalism and prey selectivity).  Forage fish dynamics appear to cycle with climate variability, yet for euryphagous predators, effects of these results remain uncertain.