Scientists have said the death of an endangered shark in the waters off Bermuda could be the first recorded example of the animals being hunted by another shark species.

According to a recent study published in Frontiers in Marine Science, researchers with Arizona State University believe a tagged porbeagle shark was killed by a white shark on March 24, 2021, near the island.

Brook Anderson, a former graduate student at Arizona State University and lead author of the paper, said it was believed to be the first example of a “predation event” of a porbeagle shark anywhere in the world.

Dr Anderson said: “In one event, the population not only lost a reproductive female that could contribute to population growth, but it also lost all her developing babies.

“If predation is more widespread than previously thought, there could be major impacts for the porbeagle shark population that is already suffering due to historic overfishing.”

Porbeagle sharks are large and highly mobile predators, reaching up to 12ft in length.

The species are found in cold-temperate waters of the Northwest Atlantic and, while they are known to reach ages of up to 65, they take years to reach maturity and reproduce.

The paper said that as part of a study into porbeagle sharks, researchers with ASU caught and tagged several of the creatures off the coast of Cape Cod between 2020 and 2022.

Pop-off satellite archival tags were used with the goal of collecting data about water pressure and temperature for a year, after which they would release and float to the surface, transmitting the collected data.

One of the tagged sharks, a pregnant female just over 7ft in length, was tagged on October 28, 2020 and its tag began to transmit data 158 days later.

The data on the tag initially showed the shark diving to around 100 metres and returning to the surface. But between December 2020 and March 2021 the shark took to deeper waters, suggesting it had moved off the continental shelf.

The readings then showed a sudden change in temperature on March 24, 2021, which the researchers believe indicated that the tag was consumed by another predator.

“The data presented in this study is, to the best of our knowledge, the first evidence of predation on a porbeagle and provides novel insight into inter-species interactions for this large, globally vulnerable shark species,” the study said.

“Knowledge gaps persist regarding natural mortality rates for porbeagles, and this work suggests predation may be an underestimated source of natural mortality for the Northwest Atlantic population.”

Based on the temperatures recorded and the location of the attack, it was believed that the porbeagle shark was attacked by either a white shark or a shortfin mako shark, with the former considered more likely.

“Tagged shortfin makos mainly occupied depths less than 400m and made rapid oscillatory dives between the sea surface and deeper depths during the day while in offshore waters of the North Atlantic, which was not characteristic of the predator’s behaviour in this study,” the paper said.

“In comparison to shortfin makos, large female white sharks spent more time at depths of 400m to 600m while in mesopelagic waters of the North Atlantic.

“Given this comparison, a white shark was likely the predator of our tagged porbeagle.”

The authors of the paper added that the data suggested that the waters near Bermuda were an area of “important inter-species interaction and mortality” for porbeagle sharks and should be an area for future research.

Choy Aming of the Bermuda Shark Project, which monitors the behaviour and movements of sharks, said that while it is not uncommon for sharks to attack each other, not many animals could tackle a mature porbeagle shark.

“Sharks will consume each other,” he said. “I have personally seen an 11ft tiger shark attempt to eat a 6ft tiger shark, but it would have to be a fairly big shark for a 7ft porbeagle.”

He agreed with the paper writer’s assessment that a great white shark was the most likely culprit because the temperatures recorded after the attack were too low for an orca, and it would be unusual for a shortfin mako to be able to take on a mature porbeagle.

“When you see a great white, it’s not the length, it's the thickness that gets you,” he said. “It’s the mass of the animal. They are enormous around the waist and they eat seals easily.”

Mr Aming said that while porbeagles have been reported in Bermuda’s waters before, they are only rarely seen in this part of the Atlantic.