Predator-Prey Interactions Among Fish-Eating Birds And Selected Fishery Resources In The Chesapeake Bay: Temporal And Spatial Trends And Implications For Fishery Assessment And Management (original) (raw)
II. To estimate the overall metabolic demand/consumption of fish-obligate breeding bird communities in order to parameterize current Chesapeake Bay ecosystem models III. To develop a novel, fishery independent tool for stock assessment of Atlantic menhaden and American shad by identifying diagnostic isotopic markers which will allow tracking of Atlantic population trends using feathers from sentinel bird species (e.g. Osprey). Summary of work performed: SPECIFIC PROJECT OBJECTIVES: 1) Quantify the complex relationships among temporal trends and geospatial patterns, and across multiple scales, using archival, long-term databases of the geographic distribution and abundance of avian predators and selected fishery resources in the Chesapeake Bay region (Chapter 1). 2) Complete a two-part retrospective analysis consisting of an analysis of stable isotopes from Bald Eagles and Osprey occupying the Chesapeake Bay circa 1850-2002 in order to estimate historical trends in the contribution of anadromous fishes, including American shad, to the diet of Osprey and Bald Eagles over very broad temporal scales. Feathers have been collected from the Smithsonian Institution (historical period) and active nests throughout Chesapeake Bay and its tidal tributaries (Chapter 2). 3) Use conventional energetics-based methods to estimate the overall metabolic demand and consumption of fishery resources for selected avian species in order to contribute to the parameterization of existing Chesapeake Bay ecosystem models (Chapters 3). 4) For most piscivorous birds comprehensive data on the composition and size distribution of fish prey are lacking. We stratified estimates of avian consumption according to fish species by compiling existing diet information for bird consumers and conducting avian diet studies for those species for which data are lacking (e.g. Osprey, Double-crested Cormorants, and Pelicans). Concurrent with avian diet studies, fishery hydroacoustic surveys were conducted to estimate available fish biomass and quantify the impact of local consumption by fish-eating birds (Chapter 4). 5) Develop and test novel, fishery independent stock assessment tool based on diagnostic stable isotope biomarkers (fatty acid signature analysis) for Atlantic menhaden and American shad in sentinel avian predators (Chapter 5).
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