Tag Data Suggest 223-Centimeter Pregnant Porbeagle Was Eaten by Larger Shark

Q: What massive predator lurks off Cape Cod capable of swallowing a pregnant, seven-foot porbeagle shark whole?

The most likely predator was a white shark, specifically a great white, researchers say. The evidence comes from the tag on the pregnant, roughly seven-foot porbeagle shark. For months it showed normal porbeagle behavior off Cape Cod: deep daytime dives, shallower nighttime movements, and temperatures that matched surrounding seawater. Then, for about four days, that changed. The shark stopped its usual vertical migrations, the depth pattern compressed, and the tag recorded a steady internal temperature of about 16 to 25 degrees Celsius—much warmer than the ocean at those depths. Researchers led by Brooke Anderson and James Sulikowski said that pattern is most consistent with the tag having been inside the stomach of a larger, heat-retaining shark. They ruled out a tag malfunction because the signal remained stable and coherent rather than erratic. They considered other possible predators, including a shortfin mako, but said the movement pattern during the final days fit white shark behavior better. White sharks are abundant seasonal apex predators off Cape Cod, where seal populations have helped create one of the densest white-shark hotspots in the western North Atlantic. The scientists were careful not to overstate the case: they did not directly observe the attack, and the finding is based on pattern matching from tag data, not visual proof. Still, the best-supported answer is that a great white shark off Cape Cod was capable of swallowing the pregnant porbeagle whole.

2 articles · Updated · spacedaily.com · Aug 17

Four days of anomalous readings from a pop-up tag off Cape Cod indicate a 223-centimeter pregnant porbeagle was likely eaten by a larger shark before the tag detached and surfaced.
Temperatures held at 16-25C and the shark’s normal day-night diving pattern vanished, a stable signal researchers said fits a tag inside a warm-bodied predator rather than equipment failure.
White sharks are the leading suspect because the depth pattern matched their longer mid-water dives better than the faster, shallower oscillations typical of shortfin makos, though the study stops short of confirmation.
Published in Frontiers in Marine Science, the case appears to be the first documented direct evidence of a porbeagle being preyed on and highlights how satellite tags can reveal deaths as well as movements.