Lampreys, the food of kings, are close to extinction

Once a delicacy which graced the tables of nobility, the fish reputedly responsible for the death of two gluttonous monarchs is on the verge of extinction.

Once a delicacy which graced the tables of nobility, the fish reputedly responsible for the death of two gluttonous monarchs is on the verge of extinction.

Lampreys, which resemble an eel with a sucker-like mouth, have roamed Scotland's rivers for millions of years. But river pollution and over-fishing have cut their numbers to such an extent that Scottish Natural Heritage fear they have been wiped out in many of their natural habitats.

The organisation is so worried about the decline of the ancient species that they have begun a major survey to try to assess how many still exist.

An important source of food at least since Roman times, the lamprey was considered a gourmet dish during the Middle Ages. Unlike other fish, it has no scales, jaws, gill covers or bony skeleton. Both King Henry I and King John of England are reputed to have been inordinately fond of it, but unfortunately died as a result of over-indulging.

Fossil evidence has shown that brook, river and sea lampreys, which belong to the family Petromyzonidae - meaning stone-sucker - date from before dinosaurs. The lamprey is a parasite, attacking fish and other aquatic species by latching on to them with powerful suckers and using a rasping tongue and sharp teeth to open wounds on the victim's skin. Then it feeds on blood and other body tissue.

Their decline has been so dramatic in areas of Europe it is feared they have been wiped out in many traditional breeding grounds. SNH fear that is happening in Scotland. Dr Colin Bean, its freshwater advisory officer, said: "Their presence is an indication of the health of the river: they rely on clean, undisturbed river systems and they affect the complex food web by feeding on a variety of species."