title: Intraspecific variation in vertical habitat use by tiger sharks (Galeocerdo cuvier) in the western North Atlantic.
abstract: Tiger sharks (Galeocerdo cuvier) are a wide ranging, potentially keystone predator species that display a variety of horizontal movement patterns, making use of coastal and pelagic waters. Far less, however, is known about their vertical movements and use of the water column. We used pop-up satellite archival tags with two data sampling rates (high rate and standard rate tags) to investigate the vertical habitat use and diving behavior of tiger sharks tagged on the Puerto Rico-Virgin Islands platform and off Bermuda between 2008 and 2009. Useable data were received from nine of 14 sharks tagged, tracked over a total of 529 days. Sharks spent the majority of their time making yo-yo dives within the upper 50 m of the water column and considerable time within the upper 5 m of the water column. As a result, sharks typically occupied a narrow daily temperature range (∼2°C). Dives to greater than 200 m were common, and all sharks made dives to at least 250 m, with one shark reaching a depth of 828 m. Despite some similarities among individuals, a great deal of intraspecific variability in vertical habit use was observed. Four distinct depth distributions that were not related to tagging location, horizontal movements, sex, or size were detected. In addition, similar depth distributions did not necessitate similar dive patterns among sharks. Recognition of intraspecific variability in habitat use of top predators can be crucial for effective management of these species and for understanding their influence on ecosystem dynamics.
authors: The Guy Harvey Research Institute, Nova Southeastern University Oceanographic Center Dania Beach, Florida.
authors: Jeremy J
authors: JJ
authors: Vaudo
authors: The Guy Harvey Research Institute, Nova Southeastern University Oceanographic Center Dania Beach, Florida ; Department of Biological Sciences, University of Rhode Island Kingston, Rhode Island.
authors: Bradley M
authors: BM
authors: Wetherbee
authors: The Guy Harvey Research Institute, Nova Southeastern University Oceanographic Center Dania Beach, Florida.
authors: Guy
authors: G
authors: Harvey
authors: Center for Marine and Environmental Studies, University of the Virgin Islands Charlotte Amalie, St. Thomas, US Virgin Islands.
authors: Richard S
authors: RS
authors: Nemeth
authors: The Bermuda Shark Project Flatts, Bermuda.
authors: Choy
authors: C
authors: Aming
authors: The Bermuda Shark Project Flatts, Bermuda.
authors: Neil
authors: N
authors: Burnie
authors: Microwave Telemetry, Inc. Columbia, Maryland.
authors: Lucy A
authors: LA
authors: Howey-Jordan
authors: The Guy Harvey Research Institute, Nova Southeastern University Oceanographic Center Dania Beach, Florida.
authors: Mahmood S
authors: MS
authors: Shivji
keywords: Depth distribution; Pop-up Archival Transmitting tag; dive behavior; individual variation; movements; telemetry