Sharks risk being driven to extinction due to overfishing, with almost 100 million killed each year, scientists have warned.

Many species of shark need better protection to prevent their extinction within coming decades, researchers warned in advance of a global conference on the trade in threatened species.

The Convention on International Trade in Endangered Species (Cites) will consider greater protection of vulnerable sharks, including porbeagles, oceanic whitetip and three types of hammerhead to preserve their populations.

Sharks are caught for their fins for use in shark fin soup, a delicacy in Asia. The fins are cut off with the dead carcass being thrown back into the sea. Sharks grow slowly and take years to reproduce, which makes them vulnerable to overfishing.

The researchers estimated that global reported catches, unreported landings, discards and sharks caught and thrown back after their fins were cut off – a process known as finning – added up to 97 million fish caught in 2010.

The figure is only slightly less than the estimated 100 million caught in 2000, and could be anywhere between 63 million sharks and 273 million a year, according to research by North American scientists published in the journal Marine Policy.

It is estimated that between 6.4% and 7.9% of all sharks are killed each year, leading to decline in the number of some species.

Boris Worm, one of the report's authors, from Dalhousie University in Halifax, said: "Biologically, sharks simply can't keep up with the current rate of exploitation and demand. Protective measures must be scaled up significantly in order to avoid further depletion and the possible extinction of many shark species in our lifetime."

Although some regions, including the European Union, have banned shark finning, commercial fisheries for fins, meat, liver oil, cartilage and other body parts are largely unregulated in much of the world.

Under the proposals put forward by the Cites meeting, five shark species would be listed as "Appendix II", which would ensure that any international trade in them is sustainable and legal.

A previous attempt to have the trade in some species of shark monitored and regulated under the Cites treaty narrowly failed, but the conservation charity Pew Environment Group believes there is a great deal of momentum behind the latest bid. Elizabeth Wilson, Pew manager of global shark conservation, said the proposals had broad support across developed and developing countries and campaigners.

"We are now the predators. Humans have mounted an unrelenting assault on sharks, and their numbers are crashing throughout the world's oceans," she said.

"A simple vote 'yes' to support their listing could turn things around for some of the world's most threatened shark species. Countries should seize this opportunity to protect these top predators from extinction."

The Cites meeting is also considering protection for manta rays, which are being fished for their gill plates, sold in China as medicine and claimed to treat a range of health complaints from asthma to chicken pox and even cancer.

The trade is on the increase, with Mozambique recording an 86% decline in sightings of the fish over the past eight years, but manta rays are very important for tourism and attract divers who will pay a lot to see them.

The UK environment minister Richard Benyon said: "We want to see better protection for sharks and will be pushing for this strongly at Cites next week. I am keen to see trade controls introduced for vulnerable and endangered species like porbeagle, hammerhead and oceanic whitetip sharks and manta rays."