Consumers of shark fin soup — a delicacy served in Washington and major cities around the country — may be unwittingly consuming animals threatened with extinction, according to a analysis released Thursday.

A team of scientists from Stony Brook University and Chicago’s Field Museum, working in conjunction with the Pew Environment Group, found that some of the soup purchased in 14 major U.S. cities featured fins from imperiled species — including scalloped hammerheads, smooth hammerheads, school sharks and spiny dogfish.

All four species face some threat of extinction, according to the International Union for Conservation of Nature.

“The soup test is significant because it shows the United States is also contributing to the global decline of sharks. And Americans who eat the shark’s fin soup may be consuming an endangered species without even knowing it,” Liz Karan, manager of global shark conservation at the Pew Environment Group, said in a telephone call with reporters. “This is bad for sharks, but also bad for the ocean environment.”

About one-third of all shark species are vulnerable to extinction, according to the IUCN, because they are targeted for their fins and because they are caught accidentally by vessels fishing for species such as tuna and swordfish.

Researchers found fins from blue shark, which reproduces more quickly than other species and is not imperiled, in one of four bowls of soup purchased in the Washington area. They could not identify the shark species in the other three bowls.

The group declined to say where it had bought the soup. At least two Maryland establishments, Rockville’s Tysons Buffet & Restaurant and Silver Spring’s Wong Gee Asian Restaurant, sell shark fin soup. According to the Animal Welfare Institute, at least nine restaurants in the region have offered it in recent years.

“We are not trying to attack the people serving the soup. They are not doing anything illegal,” Pew spokeswoman Rachel Brittin wrote in an e-mail. “It’s up to state government to ban the possession, sale and trade of shark fin.”

Five U.S. states — California, Hawaii, Illinois, Oregon and Washington — have banned the sale, trade and possession of shark fins. A similar measure in Maryland passed the state Senate this year but failed to make it through the House.

Once a shark is caught and finned, the dried fins generally are sent to Hong Kong, the global center of the world’s fin trade, and then exported. Demian Chapman, who co-led the genetic testing at the Institute for Ocean Conservation Science at Stony Brook University, said he was initially skeptical of whether they would be able to extract DNA from the “fin rays,” which have been dried and chemically processed.

“With that sort of assault, the DNA that’s left in the fin becomes very damaged,” Chapman said. But Chapman and his colleagues were able to identify 32 shark DNA samples, at which point researchers at the Field Museum’s Pritzker Laboratory compared the sequences to ones contained in the NIH genetic database GenBank.

In addition to buying soup in Washington, the group purchased it in Albuquerque, Atlanta, Boston, Chicago, Denver, Houston, Las Vegas, Los Angeles, New York, San Francisco, Seattle, Orlando and Fort Lauderdale, Fla.

Chapman said that though the United States effectively regulates shark fishing in its own waters, “Every nation gets poor marks for [inadequately] monitoring this trade, which is a global threat.”