Trophic Structure and Temporal Trends in Diets of the Demersal Fish Community of Chesapeake Bay

Continued efforts in developing and implementing ecosystem approaches to fisheries management rely on a thorough understanding of food web structure and dynamics.  This study synthesizes nine years of fish stomach content data from the Chesapeake Bay Multispecies Monitoring and Assessment Program (ChesMMAP) which surveys the bay-wide demersal fish community of Chesapeake Bay five times a year.  The objectives of this study were to 1) identify functional trophic guilds and characterize how different species partition (or potentially compete) for food resources and 2) examine how species and trophic guilds respond to changes in prey abundance and environmental factors through time.  A total of 36 species (>22,000 stomachs) were analyzed and many species were further categorized into size classes that exhibited distinct feeding habits (total of 60 groups).  Species and size classes categorized into the same trophic guild often exhibited similar temporal trends in diets, shifting among dominant prey types.  Time-series and multivariate techniques were used to assess the relative importance of several biotic and abiotic factors influencing dietary patterns.  Analyses indicated that many Chesapeake Bay fishes are feeding generalists and results are consistent with foodweb structure being largely regulated through bottom-up forcing.  Results will aid in informing ongoing ecosystem modeling efforts in Chesapeake Bay by providing thorough diet information but also by characterizing factors that mediate trophic pathways in this system.