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Sea Turtles Apparently Don’t Fear Tiger Sharks, Study Shows

By Dustin Wicksell
Published on: 11:58 PST, Jul 30, 2015

Sea turtles may be a primary food source for tiger sharks, but a newly published study in the journal Ecology asserts that the animals don’t change their habits when the predators move into their neighborhood.

The study was conducted by researchers from several universities, including the Rosenstiel School of Marine & Atmosphere Science at the University of Miami and the University of Exeter, according to CNET, who tagged both turtles and tiger sharks in the Northwest Atlantic. Following the adult female loggerhead sea turtles and their predators via satellite, the research team found that the tiger sharks follow their prey to nesting areas in the Carolinas, moving into the region in summer months.

Interestingly, the researchers also found that the turtles’ behavior appears to be unchanged by the presence of the tiger sharks. The animals failed to alter their surfacing or migration patterns, even when the sharks were detected in the area, seemingly in direct contradiction to the “landscape of fear” model. This theory asserts that the turtles’ natural fear of the sharks would produce observable changes in their behavior and distribution.

Sea turtles surface more often in summer, a habit that scientists believe is due to an increased metabolism and which allows them to more easily navigate. The tiger sharks, by contrast, have been observed modifying their surfacing behavior in a manner consistent with increasing their opportunities to prey upon the turtles.

Despite their status as a prey animal, sea turtles do possess certain defenses when it comes to tiger sharks. Last year, footage emerged of a turtle deftly deflecting a shark, simply by swimming in an ever-tightening circle. As the Inquisitr previously reported, this allows the turtle to take advantage of the shark’s length, preventing it from being placed in a position where the tiger shark could easily injure it.

The research team behind the study notes that their conclusions may have wide-ranging implications, not only for evolutionary biology, but also wildlife conservation. Neil Hammerschlag, a research assistant professor at the Rosensteil School, noted that the turtles’ seeming indifference to the tiger sharks could suggest that the predators’ numbers have been thinned by overfishing, making them less of a factor in their prey’s behavior, as Discovery News reports.

“In addition to the unpredictability of a shark attack over such a large area,” he said, “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.”

[Image via Wikipedia/ Albert Kok]

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