LONDON — Order fish and chips in Britain and you would normally expect to find a fillet of battered cod or haddock lying atop the thick-cut fries.

It would certainly be a surprise to find endangered shark on the menu.

But a study by the University of Exeter in southwest England has shone a light on the labeling of a species of shark — called a spiny dogfish or spurdog — as rock salmon, rock or huss for use in the traditional dish.

Because consumers in Britain would traditionally have balked at eating shark, terms like rock salmon have been used to make the fish sound more palatable. Few would know that ordering rock salmon, which can refer to several species of small shark, could mean they were eating an endangered species.

The researchers analyzed the DNA of more than 100 samples from takeout restaurants, fishmongers and a wholesaler, mainly in the south of England.