Region-specific movements of oceanic whitetip sharks in the western North Atlantic Ocean revealed by long-term satellite tracking

The oceanic whitetip shark (Carcharhinus longimanus) is a widely distributed species capable of long-distance travel, but relatively little is known about its long-term horizontal movements. We examined the seasonal movements and space use of oceanic whitetip sharks at two locations in the western North Atlantic using satellite telemetry. Twenty-three sharks (7 tagged off the Bahamas, 16 tagged off the Cayman Islands) were tracked for periods up to 929 d (Bahamas: 49–740 d; Cayman Islands: 314–929). Sharks displayed region-specific movements, with little distributional overlap between the Caribbean Sea and the outer western North Atlantic. Sharks tagged off the Bahamas showed a considerable individual variation in the timing of movements, but in general ranged over a larger area and made excursions as far north as Virginia, USA, during the summer and autumn. Movements of sharks tagged off the Cayman Islands were more restricted, with these sharks rarely leaving the northern Caribbean Sea. During these restricted movements, sharks in the Caribbean experienced little change in productivity and front index over time, but temperature fluctuated seasonally. Productivity and front index at the Bahamas tagging location were also relatively constant and similar to those experienced by sharks in the Caribbean, however, conditions to the north were more dynamic. During the summer, temperatures of the northern waters used by sharks tagged in the Bahamas approached those near the tagging site. The seasonally warming temperatures allow the sharks to expand their range northward where they experience stronger fronts, which may provide increased foraging opportunities.