WASHINGTON - High-tech forensic methods show that some shark fins on sale in Hong Kong markets come from endangered shark populations, proving the need for stronger trade regulations, a new study said Tuesday.

US scientists using a type of DNA testing said they were able to trace the geographic origin of shark fins on sale in Hong Kong and show that endangered species are being targeted by the trade.

The group is calling for the March 2010 meeting of the Convention on International Trade in Endangered Species (CITES) to draw up trade regulations to protect hammerhead and other shark populations.

"This trade has operated for years and years under the cover of darkness," said Demian Chapman, a lead author of the research who is based at Stony Brook University's Institute for Ocean Conservation Science, near New York.

"Our work shows that the scalloped hammerhead fin trade is sourced from all over the globe and so must be globally tracked and managed."

The group's research, to be published Tuesday in the Endangered Species Research journal, describes how the team analyzed fingernail-sized DNA samples from 62 scalloped hammerhead shark fins they purchased in a Hong Kong market.

The researchers used a technique known as "genetic stock identification" or GSI to examine each fin's mitochondrial DNA sequence.

The process is based on a DNA test developed in 2005 to distinguish between similar types of hammerhead shark and has been used to trace the geographic origin of some fish, sea turtles and marine mammals.

The study was the first time the technique had been applied to sharks and allowed the researchers to trace the geographic origin of 57 of the 62 purchased fins.

They found 21 percent of the Hong Kong fins came from endangered scalloped hammerhead shark stocks in the western Atlantic.

"The fact that scalloped hammerhead shark DNA shows strong population DNA signatures means that we can trace the geographic origin of most of their fins sold at markets," said Mahmood Shivji, a senior author of the research.

"From a broader perspective, this type of DNA forensic testing of fins will be an incredibly useful tool to prioritize areas for conservation and ensure sharks aren't wiped out in particular regions by excessive fishing," added Shivji, who heads the Guy Harvey Research Institute and Save Our Seas Shark Center at Nova Southeastern University in Florida.

Shark fins, which are often used to make a soup that is considered a rare delicacy by some, are highly sought after.

Just one kilogram (2.2 pounds) of scalloped hammerhead shark fin can sell for about 120 dollars in Hong Kong for use in soup, according to the researchers.

"Inadequate protection, combined with inexorable pursuit, has placed many shark species at grave risk," said Ellen Pikitch, executive director at the Institute for Ocean Conservation Science.

The group hopes their research will encourage nations meeting in Qatar next year for the CITES conference to list scalloped hammerheads and five other shark species under the organization's Appendix II.

The listing "would require permits for, and monitoring of, all trade in these species across international boundaries," they said.

"The international shark fin trade must not continue to operate in secrecy," said Chapman.