In the marine food chain, large sharks are usually the only concern orcas At bay — but a new study suggests top predators may have to look out for themselves.
Researchers have found evidence pointing to the first known case of porbeagle sharks – which may be on the rise 12 feet long and 500 pounds – Large sharks killed by hunters. The findings were published Tuesday in the journal Biology Frontiers in Marine Science.
This is not the first case “Shark cannibals.” John Dodd, executive director of the Atlantic Shark Institute, who helped lead the study, said it is a common occurrence for larger sharks to eat smaller ones. “In the open ocean, size matters, but there’s always something bigger,” he said.
In some cases – Bull sharkMako 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. said Brooke Anderson, a marine biologist with the North Carolina Department of Environmental Quality.
Anderson said the female porbeagle fatality raises questions about whether the incident represents a broader trend among large predators. “With advances in technology, it’s possible that this happens more frequently than we’ve actually been able to detect,” Anderson said.
It’s impossible to know the number of sharks eaten by other sharks, Dodd added, “but if our experiences at the Atlantic Shark Institute are any indication, 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 northwest Atlantic to better understand the shark species’ whereabouts, behavior and environmental preferences. They were particularly curious about female porbeagles, which are known to cross long stretches of ocean to deliver their young.
“We were really trying to understand the habitats used by pregnant females and trying to figure out where they would 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 were placed on the sharks’ dorsal fins and used to collect water depth and information. The temperature tags store data until they finally fall off the shark, at which point the data is sent back to researchers by satellite.
The tracking devices were designed to last for a year, but after five months of the experiment, Penelope’s data had already arrived. “As soon as I got the data from that tag, I knew right away that something weird had happened,” Anderson said.
A few days before Penelope’s tag popped off off the coast of Bermuda, the water temperature A sudden spike. It remained relatively high, reaching 600 meters below sea level, which is “very unusual,” Anderson explained.
Anderson and his colleagues came to a shocking conclusion: the porbeagle was hunted and eaten by other sea behemoths. “The only explanation for that data is that the tab is now in the predator’s stomach,” Anderson told CBS News.
The researchers don’t know with 100% certainty what the culprit was, but the predator’s diving pattern, which the researchers tracked by looking at the depth data collected by the tag, was similar to white sharks they had observed in the past. . “Based on that, it’s likely, I believe, a mature female white shark,” Anderson said.
Porbeagles, which have historically been overfished, are Considered endangered in some parts of the world. Although they are already at risk, Anderson said the loss of pregnant women and their babies could prove devastating to the population.
And it’s not just sharks that could feel the ripple effects of this change. The balance of the underwater ecosystem is maintained by the rulers of the deep Keeping small predator populations in check and adding important nutrients to shallow waters.
“Humans rely heavily on the oceans for food and many other things, and the oceans need healthy shark populations,” Anderson said.
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