R EPORTS Satellite Tagging and Cardiac Physiology Reveal Niche Expansion in Salmon Sharks

• Main Authors: Kevin C. Weng, Pedro C. Castilho, Jeffery M. Morrissette, Ana M. L, David B. Holts, Robert J. Schallert, Kenneth J. Goldman, Barbara A. Block
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Subarctic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.383.9514; http://www.tunaresearch.org/reprints/weng2005.pdf

Shark populations are declining globally, yet the movements and habitats of most species are unknown. We used a satellite tag attached to the dorsal fin to track salmon sharks (Lamna ditropis) for up to 3.2 years. Here we show that salmon sharks have a subarctic-to-subtropical niche, ranging from 2- to 24-C, and they spendwinterperiodsinwatersascoldas2- to 8-C. Functional assays and protein gels reveal that the expression of excitation-contraction coupling proteins is enhanced in salmon shark hearts, which may underlie the shark’s ability to maintain heart function at cold temperatures and their niche expansion into subarctic seas. Many sharks are threatened by fishing around the world (1), and biological knowledge is urgently needed to design management strategies. Sharks have been tracked using shortterm acoustic telemetry (2) and towed satellite tags, which are attached to large, slow-moving basking and whale sharks (3, 4). Pop-up satellite