A new study by scientists at the Rosenstiel School of Marine and Atmospheric Science at the University of Miami (UM) has tracked large sharks in Miami and the Bahamas to understand how these migrating animals respond to major storms, such as hurricanes.
Researchers analyzed acoustic tag data from tiger sharks (Galeocerdo cuvier), bull sharks (Carcharhinus leucas), nurse sharks (Ginglymostoma cirratum) and great hammerhead sharks (Sphyrna mokarran) before, during and after the Hurricane Matthew in 2016 and Hurricane Irma in 2017 They found that they behaved differently depending on the species and location.
For example, in response to Hurricane Irma passing through Miami, bull sharks, large hammerhead sharks, and most nurse sharks appeared to mainly evacuate the shallow waters of Biscayne Bay, as previous studies have shown that small sharks evacuate shallow coastal waters following a storm. However, the great tiger sharks of the Bahamas remained in the shallow coastal waters, even though the site received a direct eye hit from Category 5 Hurricane Matthew, and immediately after the storm the number of tiger sharks Doubled.
“I was amazed to see that the great tiger sharks didn’t evacuate even as the eye of the hurricane hit them, it was as if they hadn’t even flinched.” said Neil Hammerschlag, associate research professor at UM Rosenstiel School and the Abess Center for Ecosystem Science and Policy. “Their numbers even increased after the storm had passed. We suspect that the tiger sharks were probably taking advantage of any new opportunities to retrieve the dead animals that were knocked over in the storm.”
“Major storms, like hurricanes, are expected to increase in frequency and intensity with climate change,” said Hammerschlag, who is also the director of the University’s shark conservation and research program. “The impact of these storms on the environment, including large sharks, is interesting and of concern for the conservation of many.”
The study was funded with grants from the Ocean Tracking Network, the Save Our Seas Foundation, the Disney Conservation Fund, and the Herbert W. Hoover Foundation. The NOAA Cooperative Biscayne Bay HFA project supported the maintenance of the acoustic receiver network in Biscayne Bay and logistical support for the boats was provided by the International Seakeepers Society.
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