The UK Fish Fryers Federation is urging better labeling of fish supplied to wholesalers and fish and chip shops to boost awareness and choice among businesses and consumers.

The announcement follows a probe by British tabloid newspaper The Mirror that found endangered species of sharks were being served up to unsuspecting ­customers at fish and chip shops.

The investigation found threatened spiny dogfish and starry smooth-hound were being passed off as rock salmon, huss and rock eels.

This is leading to calls for better labeling so wholesalers and chip shop owners know exactly which species of fish they are selling.

To add to the confusion, in some cases even cod and haddock are just cited as "fish" on chip shop menus.

"The more information you can give the consumer the better," said National Fish Fryers Federation President Andrew Crook, a long-time advocate of declaring species at the point of sale.

Spiny dogfish (Squalus acanthias) is sold in many fish and chip shops in the south of England.

Usually called huss, rock salmon or flake in the United Kingdom, spurdog or spiny dogfish is also eaten as smoked belly flaps in Germany and in the form of fillets in a number of other European countries, including Belgium, France, and Italy, a spokesperson from industry authority Seafish told IntraFish.

In the northeast Atlantic, commercial targeting of spurdog has been prohibited by the EU since 2011, although substantial numbers of spurdog are also taken incidentally as “bycatch” in a number of other fisheries, via bottom trawls, hook and line gear, and gillnets.

Spurdog are found in the North Sea, West of Scotland and the Celtic Sea -- as well as occasionally the Norwegian Sea. Fishing vessels are required to record any accidental bycatch or discards of spurdog when the catch exceeds 50 kilograms.

While it is illegal to land spurdog in the EU, it is still legal to import it from other countries where capture is permissible.

Most of the spiny dogfish comes from the Marine Stewardship Council-certified North American fishery, Crook said, although some shops may be have been tempted to use smooth hound because they thought they were supporting struggling local British fishermen.

While industry officials regularly send out information advising which species to avoid selling, they cannot force busy fish and chip owners to read it or act upon it.