Researchers shocked after 8-foot shark is eaten by a predator. But who's the culprit?
In a groundbreaking discovery, researchers have found evidence that an 8-foot porbeagle shark, a top predator, was killed by another warm-blooded predator, marking the first documented instance of such an event.
The shark was being studied as part of a broader project tracking the movements of endangered porbeagle sharks. The research, conducted by a team from Oregon State University, Arizona State University, and the Atlantic Shark Institute, was recently published in the peer-reviewed journal "Frontiers in Marine Science."
The team had been tracking the shark for five months using two different tags: a finmount tag to track geolocation when the shark’s fin surfaced, and a pop-off satellite archival tag, which recorded temperature and depth. James Sulikowski, director of the Coastal Oregon Marine Experiment Station at Oregon State University, told USA Today it was the data from the archival tag that indicated something unusual had occurred.
Shark’s Sudden Temperature Shift Points to Predator Attack
The shark, which had been swimming at depths of 1,640 to 3,280 feet, was suddenly subjected to a dramatic change in temperature, from 15°C to 25°C. This temperature spike suggested the shark had been eaten by another warm-blooded predator.
The likely culprit? Another lamnid shark, with the researchers pointing to mako or great white sharks as the most probable predators. Both of these species are larger than porbeagles and have body temperatures that typically range between 25°C and 27°C.
Second shark killed in similar circumstances
The team also tracked a second porbeagle shark a year later, which was killed in the same area and under similar conditions. This shark, swimming at around 1,968 feet, suddenly sank to the ocean floor. Its tag, designed to pop off when the shark remains stationary for an extended period, resurfaced after about three days, confirming the shark had been killed without being eaten.
What does this mean for porbeagle sharks?
Sulikowski said that with sharks as large and fast as porbeagles, the only real threat to them comes from other large sharks. While it’s common for smaller sharks to fall prey to bigger ones, an 8-foot porbeagle being eaten by another shark came as a surprise.