Warming ocean waters have the potential to change the distributions and abundances of fish as species utilize distinct abiotic environments. In addition, species must also maintain a prey base that may drive further, and be lost by, dispersal. We retrospectively investigated dietary responses over time of northwest Atlantic fishes using the fish stomach contents collected by the National Marine Fisheries Service as part of their annual trawl survey since 1973. Using diet data from 41 predators, we first replicated an historic assignment of feeding guilds to determine the consistency in community structure. Secondly, annual diet compositions across all species within each of the 5 major basins (Mid-Atlantic Bight, Southern New England, Georges Bank, Gulf of Maine, and Scotian Shelf) were ordinated using non-metric multidimensional scaling to compare the regional responses over time. Finally, metrics of feeding frequency, dietary breadth, and relative consumption were calculated for each predator species and a generalized linear model was used to identify characteristics that may influence variable responses within the community. Our results found whole communities exhibited strong, consistent, and unidirectional shifts in composition while the component feeding guilds were retained from early definitions. Species consistently experienced reduced relative consumption and feeding frequencies, especially those species with high climate vulnerability [e.g., Ocean Pout (Macrozoarces americanus)] or potential to change their ranges [e.g., Butterfish (Peprilus triacanthus)]. Variable responses within changing communities shows that some predators may come out as winners [e.g., Monkfish (Lophius americanus)] while others suffer more under this regime of environmental and biological change.
