AUSTIN (KXAN) — The path to a coronavirus vaccine could decimate the shark population because of an oil called squalene.

Shark Allies, a nonprofit group that advocates against overfishing of sharks, recently released an estimate of how many sharks would have to die to produce enough of the oil—which is already used in certain flu vaccines—to serve people worldwide.

In flu shots, about 10 mg of squalene is added to produce a more effective immune response, according to World Health Organization.

The livers of sharks are mostly made of squalene and the animals use the oils to help regulate their buoyancy, Oceana says. The organization reports sharks that live in deeper waters have more oil in their livers. This makes deep-sea sharks a target.

Aside from flu shots, squalene can also be found in cosmetic products from anti-aging cream to lip gloss. The compound can also be found in other sources, like humans, animals and plants.

“Squalene made from shark liver oil is used most commonly, because it is cheap to obtain and easy to come by, not because it is more effective than other sources,” Shark Allies’ Change.org petition reads.

Shark Allies says an estimated 2.7-3 million sharks are already killed each year, and that this number could grow exponentially to produce COVID-19 vaccines. The group estimates about 3,000 sharks would be required to produce 1 ton of squalene.

The Change.org petition continues: “In a nutshell, exploiting sharks for a key vaccine ingredient that can be derived from more sustainable and reliable non-animal alternatives is a detrimental and destructive approach.”