Though the iconic movie Jaws may have planted sharks as vicious human killers, the truth is that more humans kill sharks every year than vice versa. However, the biggest shark death toll in history has nothing to do with humans, and scientists are still trying to understand this massive decline in the shark population that happened millions of years ago. According to researchers from Yale and the College of the Atlantic, 19 million years ago there was a massive death of sharks.
“We happened upon this extinction almost by accident,” said, Elizabeth Sibert. She is a Hutchinson postdoctoral associate in Yale’s Department of Earth and Planetary Sciences and the Yale Institute for Biospheric Studies. “We decided to generate an 85-million-year-long record of fish and shark abundance, just to get a sense of what the normal variability of that population looked like in the long term.” She is also the lead author of this study which has been published in the journal Science.
According to Sibert, said more than 70% of the world’s sharks died during this period. It should be noted that around this time, there were 10 times more sharks swimming around the world’s oceans than there are today.
This happened after the Cretaceous-Paleogene mass extinction event 66 million years ago where three-quarters of the plant and animal species on Earth were wiped away. The second shark death event was nearly twice that of the Cretaceous-Paleogene extinction.
It is a mysterious near-extinction event as no major natural/climate calamities happened during that time to explain this mass death event. This event changed the lives of ocean predators forever.
Co-author Leah Rubin said this study is relevant in understanding the repercussions today’s declining shark populations would have on future ocean ecology. Rubin is a doctoral student at the State University of New York College of Environmental Science and Forestry.
The researchers involved with this study hope this could help unravel any larger, previously unknown, perturbance in global ecosystems. The researchers claim the time represents a major change in ocean ecosystems at a time that was previously thought to be unremarkable.