Researchers tagged a pregnant porbeagle shark and monitored it for five months. When the tags went silent the researchers realized that the mother-to-be had been eaten. The pregnant porbeagle shark was probably a meal for a great white shark, researchers believe.
The fatal encounter is causing marine biologists to re-think the hunting habits of larger sharks. They may eat each other more than was previously believed.
According to CNN the results of the findings were recently published in the journal Frontiers in Marine Science. Frontiers “explores ocean-based solutions to emerging global challenges.” The incident occurred between 2020 and 2021.
“This is the first documented predation event of a porbeagle shark anywhere in the world,” said lead study author Dr. Brooke Anderson, a marine fisheries biologist in the North Carolina Department of Environmental Quality, via email.
Porbeagle sharks, which are found across the Atlantic and South Pacific oceans and Mediterranean Sea, can reach a little more than 12 feet (3.7 meters) long and weigh as much as 507 pounds (230 kilograms). The elusive, large sharks can also live between 30 and 65 years old. But female porbeagles can’t reproduce until they reach 13 years old. The females give birth to four pups every one or two years.” The pregnant porbeagle sharks pups were victims of the attack as well.
According to CNN the shark in question ” measuring 7.2 feet (2.2 meters) long, largely remained underwater for five months, cruising along at depths of 328 to 656 feet (100 to 200 meters) at night and 1,969 to 2,625 feet (600 to 800 meters) during the day. The ocean temperature fluctuated between 43.5 and 74.3 degrees Fahrenheit (6.4 and 23.5 degrees Celsius).
But 158 days after the shark was tagged and released, the pop-off tag began to transmit data from the sea southwest of Bermuda, suggesting it had come off the shark and was floating on the ocean’s surface.
For four days in March 2021, the tag registered a constant temperature of 71.6 degrees Fahrenheit (22 degrees Celsius) at a depth ranging from 492 to 1,968 feet (150 to 600 meters). Then the tag floated up.
The team pieced together several factors that indicated the shark had been eaten and the tag excreted by a larger predator that gobbled up the shark, researchers said.
The researchers are now wondering how much shark-to-shark predation impacts the populations of larger sharks Such sharks were thought to be apex predators at little risk of being eaten.
Pregnant porbeagle sharks are not the only sharks under study. Researchers have recently discovered that bull sharks travel as far as 1,000 miles up the Mississippi River. Greenland sharks are also study subjects because they have adapted to Arctic waters and live hundreds of years. New types of sharks are still being discovered, including a new ghost shark.