A 7-foot pregnant porbeagle shark appears to have been eaten by an even larger shark, in what researchers say is the first evidence that the ocean hunter becomes the prey.
Researchers captured the porbeagle near Cape Cod, Massachusetts, in late October 2020 and attached two tracking tags — one mounted on the shark’s dorsal fin to transmit its geolocation and a second tag, called a pop-off satellite tracking tag (PSAT), that measures the shark’s temperature and depth in the ocean, the scientists wrote in a paper published Tuesday in the journal Frontiers in Marine Science.
The PSAT is designed to detach from the shark after about a year, but in this case the device detached after about five months near Bermuda.
“Something had gone seriously wrong,” Brooke Anderson, one of the researchers, told NBC News.
Data collected from the shark showed that in the days before the tag was detached, its diving habits had become erratic.
His temperature readings also increased despite swimming at a depth deep enough that they would have made the readings much cooler, the study said.
Using this data, the researchers determined that the tag had spent several days in the stomach of another animal.
Mammals like the orca were ruled out due to higher temperatures, so scientists focused on endothermic sharks.
“The data presented in this study constitute, to our knowledge, the first evidence of predation on a porbeagle shark and provide new insights into interspecific interactions of this large and globally vulnerable shark species,” the study states.
Researchers speculated that the ocean predator had fallen prey to a larger shark, only two of which are large enough to have eaten the 7-foot pregnant female: the great white shark and the shortfin mako.
James Sulikowski, director of the Coastal Oregon Marine Experiment Station at Oregon State University, who also participated in the research, told USA Today that the study shows the ocean still holds many mysteries that scientists want to solve.
“It makes us want to study more and learn more about how vulnerable other great sharks are to being eaten and who the greatest white shark is,” he said.
