Movements of sand tiger sharks, Carcharias taurus rafinesque, 1810, in the northwest Atlantic Ocean

From 2000--2006, I attached pop-up archival satellite transmitting tags to 23 sand tiger sharks, Carcharias taurus, to study their movement patterns and habitat preferences in the northwest Atlantic Ocean. Ten tags from 2003--2006 returned useable data from 9 males and 1 female. Successful tracks ranged from 29 to 184 days. Three tags popped up in state waters off New Jersey, Delaware, and Florida. Five tags popped up in U.S. Federal waters, and one began transmitting east of the Exclusive Economic Zone. Depth data indicate significant drift associated with the latter tag and several others. Depth readings of less than 0 meters were common and were problematic in delaying transmissions after most premature releases. Tagged male C. taurus spent May and June at depths of 30 meters or less. Most moved into deeper waters of up to 152 meters as summer progressed, but one shark remained in shallow depths. Ambient temperatures may influence vertical movements, as most C. taurus swam deeper in response to temperatures greater than 25°C. Light level data from tags enabled estimates of horizontal movements. Use of tag manufacturer software provided crude location estimates and the Kftrack program reduced location errors to produce Most Probable Tracks for four sharks. All male C. taurus moved north after tagging, remaining in waters off North Carolina before continuing north. Three sharks moved offshore, and one remained close to shore. MPTs for two male C. taurus indicated their presence in waters off of New Jersey and Delaware in late September and early October. The tag from the single female C. taurus to return data provided its pop-up location only. It is significant that this tag was the only tag to jettison south of the deployment location; it began transmitting in late October from a location near- or onshore in northern Florida.