Movement Patterns and Environmental Preferences of Blue Sharks (Prionace glauca) Determined by Satellite Archival Tagging

Blue sharks (Prionace glauca) are common, highly migratory, pelagic sharks with hundreds of thousands captured annually in pelagic longline fisheries. They also form the largest component of the international fin trade. Despite their prevalence in global fisheries, management relevant information on their habitat utilization and movement patterns is fragmentary. During the summer of 2007, twenty-three blue sharks (male, n=21; female, n=2) were tagged with Microwave Telemetry Inc., satellite pop-up transmitters near Cape Cod, MA. Programmed pop-off dates ranged from 30 days to 12 months. To date, tags have collected information ranging between 4-186 days with seven tags still at liberty. Blue sharks preferred surface waters and spent 43% of their time at less than 2.4 m depth, 66% of their time at depths less than 5 m (±2.4 m) and 77% of their time at less than 11 m (±2.4 m). Sharks spent 70% of their time in waters between 14-20°C. When sharks traveled off the continental shelf into deeper waters they dove more frequently. Geoposition was determined based on light level data and analyzed using the Kalman-SST filter. Sharks remained on the continental shelf during summer months, but moved to distant, off-shelf locations as the seasons progressed. One male shark moved at least 2,485 km over 6 months from its September tagging location to coastal Puerto Rican waters; another male shark moved at least 1,447 km from Cape Cod to the east of Bermuda between August and February. We will report a more detailed perspective on movement patterns from these and additional tags scheduled to release within the next few months