Great white shark attacks

Using Stable Isotope Analysis to Understand the Migration and Trophic Ecology of Northeastern Pacific White Sharks (Carcharodon carcharias)
Aaron B. Carlisle1*, Sora L. Kim2, Brice X. Semmens3, Daniel J. Madigan1, Salvador J. Jorgensen1,4, Christopher R. Perle1, Scot D. Anderson5, Taylor K. Chapple6,7, Paul E. Kanive8, Barbara A. Block1
1 Hopkins Marine Station of Stanford University, Pacific Grove, California, United States of America, 2 University of California Santa Cruz, Santa Cruz, California, United States of America, 3 Scripps Institute of Oceanography, University of California San Diego, San Diego, California, United States of America, 4 Monterey Bay Aquarium, Monterey, California, United States of America, 5 Point Reyes National Seashore, Inverness, California, United States of America, 6 University of California Davis, Davis, ¨ California, United States of America, 7 Max-Planck-Institut fur Ornithologie, Radolfzell, Germany, 8 Montana State University, Bozeman, Montana, United States of America

Abstract
The white shark (Carcharodon carcharias) is a wide-ranging apex predator in the northeastern Pacific (NEP). Electronic tagging has demonstrated that white sharks exhibit a regular migratory pattern, occurring at coastal sites during the late summer, autumn and early winter and moving offshore to oceanic habitats during the remainder of the year, although the purpose of these migrations remains unclear. The purpose of this study was to use stable isotope analysis (SIA) to provide insight into the trophic ecology and migratory behaviors of white sharks in the NEP. Between 2006 and 2009, 53 white sharks were biopsied in central California to obtain dermal and muscle tissues, which were analyzed for stable isotope values of carbon (d13C) and nitrogen (d15N). We developed a mixing model that directly incorporates movement data and tissue incorporation (turnover) rates to better estimate the relative importance of different focal areas to white shark diet