Study: Sea Turtles Aren’t Afraid of Tiger Sharks

posted: 07/31/15
by: Richard Farrell

Tiger sharks got some good news with a recent finding about the behavior of one of their staple meals, sea turtles. It seems that the shelled swimmers aren't taking extraordinary precautions to protect themselves around the predators.

In a coordinated study out of a number of universities, including the University of Miami and the University of Exeter, a team of scientists tracked satellite tagging data of tiger sharks and loggerhead sea turtles in the northwestern Atlantic Ocean.

Of particular interest to the researchers were the places where the two creatures -- predator shark and prey turtle -- overlapped. They wanted to know if the turtles would change their swimming behavior to give themselves a better shot at not being eaten when they lived near sharks.

Tiger shark profile
Evan Gross/iStock

In welcome news for the sharks, and surprising news for the scientists, it turned out the answer was no. Whenever there was lots of territorial overlap between the dinner and diner populations, the sea turtles did not alter the way they swam to the surface.

For their part, and perhaps not surprisingly, the sharks took a less blase attitude. The scientists found the smooth predators altered their surfacing behavior to give them an even better shot at a meal.

The researchers suggested that sharks just may not matter much to turtles in their movements.

"In addition to the unpredictability of a shark attack over such a large area," said Neil Hammerschlag, research assistant professor at the University of Miami, in a release, "it is possible that fishing of tiger sharks has reduced their populations to levels that no longer pose a significant threat to turtles, with other factors becoming more important such as the need to avoid boat strikes."

The scientists note that their study is among the first to test the "landscape of fear" theory -- used to explain how prey move in an environment based on their fear of predators -- against wide-ranging marine species in large, open ecosystems.

"This is one of the first studies to compare the large scale, long-term movements of sea turtles with their natural predators, tiger sharks," said study co-author Lucy Hawkes, of the University of Exeter's Centre for Ecology and Conservation.

"These data are essential for setting and prioritizing marine protection for these species, which are both of conservation concern," added study co-author Matthew Witt, of the University of Exeter's Environment and Sustainability Unit.

The team's findings have been published in the journal Ecology.

This article originally appeared on Discovery News


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