One of the most comprehensive studies ever compiled on illegal shark killing brings new startling statistics. An estimated 100 million sharks are killed every year around the world, a number that far exceeds what many populations need to recover.

The statistical report, compiled by researchers at Dalhousie University in Halifax, Canada, crunched numbers of reported shark catches globally and used data from nearly 100 former papers to estimate the number of unreported shark deaths every year. In a moving range, the researchers were able to calculate that between 6.4% and 7.9% of sharks of all species are killed annually.

To put that range in perspective, researchers analyzed life data from 62 shark species and found that only 4.9% of sharks can be killed each year to maintain population stability. Anything more than that threatens long term survival of species like the oceanic white tip, porbeagle and several kinds of hammerheads. What’s worse, sharks are considered uniquely vulnerable because they take long periods to mature and generally produce few young over their lifetimes.

View Images Photo by Shawn Heinrichs / Pew Environment Group

The culprit is the proliferation of illegal shark finning that spiked in the 1990s to feed appetites for shark fin soup, a delicacy in parts of Asia on par with fine truffles or expensive caviar. According to some reports, a bowl of shark fin soup can sell for as much as $100.

While some sharks are allowed to be caught, illegal shark finning occurs when fisherman cut fins off live sharks and dump their bodies into the open ocean to avoid declaring the full animal at port and surpassing fishing quotas.

“There’s a staggering number of sharks being caught every year and the number is way too high considering the biology of species,” says Dalhousie biologist Boris Worm, the study’s lead researcher. The 100 million sharks was actually a conservative estimate. Worm’s team found the number could be as high as 273 million sharks killed each year.