It's dangerous living in the open sea, but researchers have discovered that loggerhead sea turtles don't make an effort to avoid tiger sharks, their natural predator.
In a study published in the journal Ecology, researchers from the University of Miami's Rosenstiel School of Marine and Atmospheric Science and the Abess Center for Ecosystem Science and Policy assessed the predator-prey relationship between tiger sharks and sea turtles in the Northwestern Atlantic Ocean by using long-term satellite tagging data, examining movement patterns to evaluate if loggerhead sea turtles modify their behaviors to lessen chances of being attacked by tiger sharks when their home ranges overlap.
According to the results, tiger sharks change their movements depending on the season to take advantage of nesting turtles during the summer in the Carolinas, mainly attacking surfacing sea turtles from below. Loggerhead turtles should react accordingly and avoid exposure as much as possible in areas where the tiger shark population is high but the researchers were surprised to find that they didn't change their behavior at all to reduce their risks.
Based on their findings, the researchers suggest that sharks are not that important when it comes to potential factors that influence behavior and movement in sea turtles in the Northwestern Atlantic Ocean. Instead, loggerheads may be more concerned with avoiding other threats like boat strikes. The researchers also think that a reduced population caused by tiger shark fishing may be dampening the intimidating image of the predator.
The study is one of the first to explore if the "landscape of fear" model is at play in the region, testing if the scientific theory that explains how animals behave within an environment is guided by their fear of predators attacking. It is also one of the first research works to compare long-term, large-scale movements in sea turtles tiger sharks.
"These data are essential for setting and prioritizing marine protection for these species, which are both of conservation concern," said Matthew Witt, a co-author for the study.
Other authors include Lucy Hawkes, Kristina Williams, Emily Rose Nelson, Thomas Murphy, Sally Murphy, Kyra Hartog, DuBose Griffin, Brendan Godley, Matthew Godfrey, Michael Frick, Mark Dodd, Michael Coyne, John Coker, Annette Broderick and Neil Hammerschlag.
Photo: Angell Williams | Flickr
