A PREHISTORIC river dweller with a menacing way of catching food has been seen in Cumbria’s rivers for the first time in three years.

Several pairs of sea lampreys – a breed which has remained unchanged for 500 million years – have been spotted in the River Leven, giving local conservationists an ‘encouraging indication’ of the health of local waterways.

But this is not good news for other fish in the area, which could become lunch to the vampiric animal which feeds by sucking out blood through an incision it makes in its prey.


“It is extremely grim,” said Dr Mike Sturt, of the Cumbria Rivers Trust. “But they’ve been around for millions of years so it’s obviously working for them!”

He explained that the sea lamprey was a common sight in UK rivers until recent decades but suffered a dramatic decline and is now a protected species.

This is the first year in several that it has actually been seen in the Leven by Dr Sturt.

The ancient snake-like creature resembles an eel, but unlike most fish lacks scales, jaws and gill covers and has a cartilaginous skeleton.

Its sucker-like mouth, pointy teeth and rasping tongue are by far its most unusual feature.

And according to Dr Sturt its creepy appearance is ‘matched by its feeding strategy’.

“They use their mouth to stick on to the side of fish, use their tongue to scrape a hole into the fish’s flesh and then drink the fish’s blood,” he said.

“They use their anti-coagulant saliva to stop the blood from clotting until they have had their fill.

“On the top of their heads they have a ‘pineal gland’ which detects changes in light and helps the lamprey detect its prey.”

As its name suggests, the sea lamprey spends most of its life at sea but returns to freshwater environments to spawn.

It relies on clean, undisturbed river systems to breed so sightings of spawning Lampreys in South Lakeland suggest the region’s rivers are in good health.

Now several pairs have built nests – or ‘redds’ – in the Leven’s gravel river bed and have laid between 10,000 and 100,000 eggs in each one.

The eggs will remain in the gravel for several weeks where the flowing water will provide oxygen for the developing embryos.

Once hatched, the young Lamprey larvae will move to slower flowing areas of the river before migrating to sea for around two years.

“The protection of this fascinating prehistoric creature is at the heart of South Cumbria Rivers Trust’s work,” added Dr Sturt.

“This involves habitat improvements which include river bank protection, reducing pollution and installing fish passes to allow eels and lamprey to navigate over man-made structures such as weirs.”


  • There are about 38 known species of lamprey, sometimes called lamprey eels.
  • Adult lampreys have large eyes, one nostril on the top of the head and seven gill pores on each side of the head.
  • Lampreys live mostly in coastal and fresh waters although some species travel significant distances in the open ocean.
  • Attacks by lampreys on humans do occur, but they do not happen unless the fish is starved.
  • Lampreys have long been used as food for humans