Depth and Movement Patterns of the Blacktip Shark at a Migrational Terminus

Many marine species make use of the expanse of the ocean by travelling great distances to benefit their life histories. The blacktip shark, Carcharhinus limbatus, is a medium sized, coastally associated species that is found circumglobally in warm temperate waters. In the northwestern Atlantic Ocean, blacktips migrate in large aggregations along the eastern coast of the United States annually from the Carolinas in the summer months to a terminus in south eastern Florida in the winter. Upon reaching their Florida habitat, these aggregations remain visible in the shallow coastal waters frequented by tourists and anglers. What activities these sharks undergo during their multi-month residency at this southern terminus has largely been unquantified. We employed fin-mounted accelerometer tag packages to record high resolution data from 5 individual blacktip sharks during their winter residency in southeast Florida. We show the diel changes in behavior through depth range inhabited and the swimming velocity used. Our data provide the basis to understand activity patterns and general habitat use by these individuals within the aggregation during their winter residency. These data reveal the environmental conditions that the sharks inhabit and can be used managers and climate modelers to better understand how changing conditions may affect habitat use and behavior of these commercially and recreationally important species.