Migratory Patterns and Habitat Use of Sand Tiger Sharks (Carcharias taurus) in the Northwest Atlantic

Though there is concern over declines in sand tigers ( Carcharias taurus ) in the Northwest Atlantic Ocean, details of their habitat use and movement patterns in the open ocean are limited. We report on the vertical and horizontal movements of sand tigers off the US east coast using archival pop-up satellite transmitters. Transmitters were deployed on 13 sand tigers (168 - 232 cm TL) in Delaware Bay in late summer 2008. Duration of tracks ranged from 12-154 days (x ̄=105), allowing reconstruction of 12 horizontal tracks using light-level data and a Kalman filter state-space model. Seven of the males exhibited directed movements south along the US east coast to waters off North Carolina, whereas all three females initially moved eastward into deeper offshore waters and remained largely in waters off New Jersey to Virginia. While in Delaware Bay, sand tigers spent the majority of their time at depths of less than 10 m and at 19-22 ^o C. During their migration south, males occupied deeper water, primarily 20-80 m (max depth 188 m), and upon arrival in North Carolina waters in late 2008 or early 2009, some males moved into shallower water. Female sharks generally inhabited shallower water during their migrations, remaining predominantly at depths < 50 m (maximum depth 92 m). Water temperatures occupied by sharks ranged from 13-26 ^o C, with females averaging 21-23 ^o C and males 19-24.5 ^o C. These initial results suggest possible differences in the movement behavior of male and female sand tigers, but need confirmation by tracking more animals of each gender.