Habitat use, movement and residency of bull sharks Carcharhinus leucas were determined using satellite pop-up archival transmitting (PAT) tags throughout coastal areas in the U.S., Gulf of Mexico and waters off the south-east U.S. From 2005 to 2007, 18 fish (mean size = 164 cm fork length, L(F)) were tagged over all seasons. Fish retained tags for up to 85 days (median = 30 days). Based on geolocation data from initial tagging location to pop-off location, C. leucas generally travelled c. 5-6 km day(-1) and travelled an average of 143.6 km. Overall, mean proportions of time at depth revealed C. leucas spent the majority of their time in waters <20 m. They exhibited significant differences among depths but were not found at a particular depth regardless of diurnal period. Most fish occupied temperatures c. 32 degrees C with individuals found mostly between 26 and 33 degrees C. Geolocation data for C. leucas were generally poor and varied considerably but tracks for two individuals revealed long distance movements. One fish travelled from the south-east coast of the U.S. to coastal Texas near Galveston while another moved up the east coast of the U.S. to South Carolina. Data on C. leucas movements indicated that they are found primarily in shallower waters and tend to remain in the same location over long periods. While some individuals made large-scale movements over open ocean areas, the results emphasize the importance of the coastal zone for this species as potential essential habitat, particularly in areas of high freshwater inflow.

Defining the location and habitat characteristics of areas of aggregation of Atlantic shark species has been identified as an important information need for current and future management efforts. The primary objective of this project was to investigate the depths and temperatures of the waters occupied by large juvenile sandbar sharks of the northwest Atlantic population during the winter months and the overwintering localities of these animals using a fishery independent method. During the summer of 2003, 21 sandbar sharks captured in the Eastern Shore of Virginia bays and lagoons were outfitted with satellite transmitters that were programmed to detach during the following winter. The sharks occurred in significantly colder and deeper waters during the winter period than during the summer nursery period with a mean depth and temperature recorded by the transmitters during the winter period of 19.98C and 20.8 m and a mean depth and temperature recorded during the summer period of 24.08C and 4.3 m. Despite this decrease in temperature and increase in depth of occurrence, the sharks remained in relatively warm waters and shallow depths throughout the overwintering period. Satellite pop-off locations during the overwintering period were concentrated in central North Carolina coastal waters, where a unique combination of shallow depths and warm temperatures may contribute to the survivorship of these animals while they overwinter in these waters.