COS 100-1 - Integrated sampling methods establish fine- and large-scale habitat associations of fish communities, species, and individuals on the New Jersey shelf

Abstract: Sand dredging is extensive offshore of New Jersey, used for rebuilding beaches and in such materials as concrete. While previous research has established large-scale distributions and fish communities on sandy shelf habitat, this is the first to look at fine-scale relationships to microhabitats. We examine how fish communities and individuals use spatial gradients and microhabitats to establish a baseline for establishing localized aftereffects of sand dredging. We show how inferences from three techniques may be used to mutually measure fish associations at different scales. We use acoustic imaging from sidescan sonar on an autonomous underwater vehicle (AUV) to characterize microhabitats and map these to detailed large-scale bathymetric structure, and to classify pelagic fishes observed at these habitats. Trawls characterize assemblage structure further mapped to larger-scale depth and latitudinal gradients, from which provides the basis for finer inference of fish identity at finer scales. Finally, acoustically-tagged fishes allow us to follow individuals through the site, measuring fine-scale connectivity from the perspective of different species. We demonstrate how these methods may be integrated to provide greater information that when analyzed individually. Species show differential associations with microhabitat, bottom complexity, and depth gradient, with communities reflecting high degree of localization in space. Thus, fishes may be sensitive to small shifts in bathymetry and hydrographic processes. These findings suggest that offshore sand-dredging has the potential to impact localized distributions through habitat alteration.