Blood-sucking fish on the rise in the our rivers

The number of lampreys, which are known to attack humans when hungry, are soaring all around the UK, with record numbers found in some of the country's water ways.

The rise in the 'vampire fish', which kill off other fish by latching onto them and sucking their blood out, has been flagged up on outdoor swimming websites where members swim in rivers and lakes.

The Swimmer's Daily website carried a report into the rise of the lampreys warning swimmers 'Return of the lamprey – ancient, ugly and swimming up Britain's rivers'.

Outdoor swimmers are now 'keeping an eye out' for the blood-sucking creatures during dips in rivers. As well as the Trent, they have been spotted in the Great Ouse, Trent, Derwent and Wear.

Wild swimmer Matt Clarke, who swims all over the UK, but who normally swims in the River Great Ouse as it runs through the town of Olney, Bucks, said he was alerted by a pal last week who saw a warning on the Swimmer's Daily website.

Mr Clarke, 31, of Milton Keynes, Bucks, said his pal also alerted him to an episode of ITV show River Monsters aired in May 2013 about lampreys and called 'Vampires of the Deep'.

The show, which stars biologist Jeremy Wade, shows him up to his shoulders in a lake with a lamprey attached firmly to his neck as it sucks out his blood.

Speaking during the episode, Mr Wade says: "The parallels with vampires are striking – they both tap into that that same dark place, the primal fear they will drain the life force from us."

As he stands in the shoulder-height river with the creature sucking out his blood, he says: "There's suction, but there is something sharp going on as well.

"If you get these things attached you're going to want to get them off."

He warned swimmers: "If you're swimming you're needing your limbs to keep you afloat and to keep you moving, but what are you going to do (if) you've got these attached to you? Do I carry on swimming with maybe more and more attaching (to me), or do I stop swimming and try and get these things off – these things are like aquatic vampires."

The TV host was investigating reports of lamprey attacks on swimmers at Lake Champlain in north America in 2007, with several swimmers reporting 'being attacked' by up to seven lampreys at a time

The attacks on humans at Lake Champlain were made into a 2014 movie called Blood Lake: Attack of the Killer Lampreys, starring Back to the Future star Christopher Lloyd and Beverly Hills, 90210 star Shannon Doherty.

Accounts worker Mr Clarke said: "My friend told me to watch out for lampreys as he'd seen the River Monsters episode and heard that lampreys were on the rise around where I normally swim.

"I'm not really worried, but after watching that episode online last week I will be keeping an eye out for them."

The numbers of lampreys – which have been around for 360m years and have a permanently open mouth armed with a powerful sucker and rows of razor-sharp teeth – in the UK have shot up in recent years. Numbers had been dwindling after man-made barriers to alter the flow of the water, called weirs, prevented them from swimming upstream to their breeding grounds, where females lay around 170,000 eggs at a time.

Mark Owen, head of freshwater at the Angling Trust, said last week that 'fish passes' allow lampreys to get through weirs had helped boost numbers.

He said: "The fact they're coming back indicates the water quality is improving, which is welcome for all fish species."