Social Sharks: Long-Term Internal Acoustic Transceivers Reveal Species Associations and Large-Scale Movements of a Coastal Apex Predator

Sand tigers (Carcharias taurus) are large apex predators common in the coastal ocean along the Eastern US Coast. Although Delaware Bay and surrounding coastal waters are known summer hot-spots for Sand Tigers, our understanding of where this population travels throughout the year is less well known. Since 2007, we have implanted more than 300 VEMCO acoustic transmitters in Sand Tigers providing detections from Cape Canaveral, Florida to Long Island, New York by collaborators in the Atlantic Cooperative Telemetry (ACT) Network. During the summer of 2012, 20 Sand Tigers were implanted with VEMCO Mobile Transceivers (VMTs), which are capable of both transmitting and receiving coded acoustic pings. To date, two of the 20 sharks have been recaptured, and their VMTs recovered. VMTs recorded detections of 350 individuals (216 Sand Tigers), from 8 species telemetered by ACT Network researchers. This represents the species assemblages associated with Sand Tigers throughout the year. Detections of species by transceivers also created a network allowing us to piece together the locations of Sand Tigers throughout the year. This project is a unique look at the social network of an apex predator and is a useful model for studies quantifying the social structures of marine animals.