Mapping Potential Coastal Shark Habitat and Interspecies Interactions in Pamlico Sound, North Carolina

Estuaries are used as foraging and nursery habitat by many coastal shark species, but their ecological role in estuarine systems is still poorly understood.  Sharks were captured, identified, and measured during the years 2007-2014 in North Carolina Division of Marine Fisheries fishery-independent gillnet and longline surveys of Pamlico Sound.  Depth, temperature, salinity, and dissolved oxygen were recorded and straight-line distances from the nearest inlet and seagrass bed were measured at each sampling station.  These abiotic factors were interpolated across the entire area of Pamlico Sound.  For each species, cut points between presence and absence were found using correlation and regression tree analysis, and potential habitat maps were created by filling in areas of the estuary falling within the environmental ranges identified by these models.  Overlap between habitat area and spatial overlap in the field were compared to determine the relative importance of abiotic factors and avoidance behavior.  Bull Sharks, Smooth Dogfish, and Spiny Dogfish were habitat specialists based on salinity, seagrass distance, and temperature, respectively.  Blacktip, Atlantic Sharpnose, and Sandbar Sharks all preferred high salinity areas close to inlets.  Despite habitat similarities, spatial overlap was low between all species, suggesting the importance of behavior in habitat selection by coastal sharks.