In the marine food chain, large sharks generally only have to worry about survival orcas in the bay – but a new study suggests the apex predator may be worth watching out for.
Researchers have found evidence that shows the first case of a porbeagle shark – which can grow up to 12 feet long and 500 pounds – was killed by a large shark predator. The findings were published Tuesday in the biological journal Frontiers in Marine Science.
This is not the first case of “shark cannibalism.” Jon Dodd, executive director of the Atlantic Shark Institute, which helped lead the study, said larger sharks eating smaller sharks is a common occurrence. “On the open ocean, size matters, but there’s always something bigger,” he said.
In some cases – bull sharks, mako sharks and baby sand tiger sharkfor example – sharks will even eat their own species.
But cases of large sharks eating other large sharks, the subject of this study, are few and far between, said lead author Dr. Brooke Anderson, marine biologist for the North Carolina Department of Environmental Quality.
The female porbeagle’s death raises the question of whether this incident reflects a broader trend among large predators, Anderson said. “With the advancement of technology, it’s possible that this happens more often than we realize,” Anderson said.
The number of sharks eaten by other sharks is unknown, Dodd said adding, “but if our experience at the Atlantic Shark Institute is any indicator, it may be more than we think.”
A group of scientific researchers from across the US discovered the porbeagle die-off while conducting a satellite tracking project in the North-West Atlantic to better understand the shark species’ location, behavior and environmental preferences. They are especially curious about female porbeagles, which are known to cross long swaths of the sea to deliver their puppies.
“We’re really interested in understanding the habitats that pregnant females use and trying to figure out where they’re going to give birth,” Anderson said.
The victim of the attack, nicknamed Penelope by researchers, was one of 11 sharks scientists tagged off the coast of Cape Cod in 2020 and 2022. Tracking tags are placed on the shark’s dorsal fin and are used to collect information about water depth and temperature. The tag stores the data until it finally falls off the shark, and the data is sent back to researchers via satellite.
Image Gerard Soury/Getty
The tracking device is designed to last a year, but five months into the experiment, Penelope’s data has arrived. “As soon as I got the data from the tag, I immediately knew something was weird,” Anderson said.
A few days before Penelope’s tag appeared on the coast of Bermuda, the water temperature suddenly spiked. It remains relatively high, even reaching 600 meters below sea level, which is “very unusual,” Anderson explained.
Anderson and his colleagues came to a shocking conclusion: the porceagle had been hunted and eaten by another giant in the sea. “The only explanation for the data is that this tab is now in the belly of the predator,” Anderson told CBS News.
Researchers don’t know with 100% certainty what the culprit is, but the diving pattern of the predator, which the researchers tracked by looking at the depth data collected by the tags, is similar to white sharks that have been monitored before. . “Based on that, it’s probably, I would guess, an adult female white shark,” Anderson said.
Porbeagles, which have historically been overfished, are considered endangered in certain parts of the world. Because there are already risks, Anderson said losing pregnant women and their babies could devastate the population.
And sharks aren’t the only ones who could feel the ripple effects of this change. The deep-water authorities maintain the balance of the underwater ecosystem by maintaining smaller predator populations and adding essential nutrients to the shallow waters.
“Humans depend heavily on the ocean for food and many other things and the ocean needs a healthy shark population,” Anderson said.
