In a groundbreaking study published on Tuesday in the journal Frontiers in Marine Science, scientists reported that they discovered a top predator shark being killed by another predator for the first time.

The research team aimed to study pregnant porbeagle sharks and track their movements due to their endangered status in several regions globally. The scientists involved are from Oregon State University, Arizona State University, and the Atlantic Shark Institute based in Rhode Island.

One of the porbeagle sharks they observed measured 8 feet long and had been monitored for five months, explained James Sulikowski, head of the Coastal Oregon Marine Experiment Station at Oregon State University.

The researchers discovered that this substantial, warm-blooded shark had become the target of another warm-blooded predator, which they suspect could be another shark.

Porbeagle shark likely fell victim to a warm-blooded predator, researchers claim

Sulikowski noted that the research team fitted their subject sharks with two types of tags.

The first tag, known as a finmount tag, is attached to the shark’s fin and provides researchers with precise geolocation information when the fin breaches the water’s surface, he told YSL News on Tuesday.

The second tag, referred to as a pop-off satellite archival tag, records temperature as well as the shark’s depth in the ocean.

“That’s how we determined that the shark was indeed eaten or attacked,” Sulikowski mentioned about the archival tag.

The team noted that another porbeagle shark was killed not far from the first one a year later, which sank to the ocean floor before its tag surfaced, according to the scientists.

Shark was monitored on a long journey

The deceased shark had been observed making a long journey from New England to Bermuda, traveling hundreds of miles as per the scientists’ findings.

Throughout its journey, the shark spent time at depths ranging from 1,640 feet to 3,280 feet. As it dove deeper, the temperature readings from the shark showed significantly cooler temperatures. Suddenly, while still deep underwater, one of the tag’s readings spiked from 15 degrees Celsius to 25 degrees Celsius.

“We understood that something had happened,” Sulikowski stated. “We realized that the tag was inside a warm-blooded animal… and it wasn’t a whale or mammal because they are considerably warmer than that.”

The predator that consumed the porbeagle shark was likely another lamnid shark, Sulikowski explained, identifying the “iconic three” lamnid sharks as porbeagles, white sharks, and mako sharks.

According to him, these predators typically have body temperatures ranging from 25 to 27 degrees. He speculated, “My guess is that it was probably a mako or a white shark since those species are larger than porbeagles.”

Second shark sank to the ocean floor

Another shark caught the researchers’ attention; this porbeagle was spotted at a depth of around 1,968 feet before it inexplicably sank deeper into the ocean, Sulikowski stated.

The research team suspect that the second shark was killed without being consumed or its tags removed. After it sank, its tag—designed to detach when sharks remain inactive for an extended period—came back to the surface after approximately three days.

“Both sharks were attacked at nearly the same depth and in the same location, separated by a year,” Sulikowski informed YSL News.

Implications for porbeagle sharks and future research

Sulikowski remarked that considering the size and speed of porbeagles, they are likely only preyed upon by certain larger shark species.

There are larger sharks that prey on smaller ones.

Researchers already assumed that smaller sharks would be targets for larger ones, but they were taken by surprise when discovering an 8-foot shark that was unexpectedly caught, according to his statements.

This occurrence highlights just how little we truly understand about ocean life, he noted.

“This motivates us to learn more and explore which large sharks might be at risk of being eaten and to identify the dominant species in the ocean,” he remarked.