Eventually Val Fletcher, who is 5ft 4in and eight stone, landed an 11ft 4in (3.3 metres), 140lb (63.5kg) monster that turned out to be an oarfish, the ancient mariners’ legendary sea serpent.

It is believed to be the first oarfish caught on a rod and line off the coast of Britain.

Ms Fletcher’s catch off Skinningrove, Cleveland, has left marine biologists wondering why such a rare fish, which favours the 1,000 metre depths of the Atlantic, Pacific and Indian Oceans, should be found in the shallows of the North Sea. One suggestion is that it followed the Gulf Stream from the Atlantic to the North Sea, Oarfish are the longest bony fish in the sea and sport a mane-like crest behind a toothless head. They can grow up to 30 feet and weigh up to a quarter of a ton, hence their status as the original sea monster.

Ms Fletcher and her partner, Robert Herrings, were hoping for some cod or mackerel when they baited a standard rod and line with squid and cast from their favoured spot on Monday night.

Ms Fletcher said: “To say we had something big on the end was an understatement. It was absolutely colossal.

“We had a battle on our hands to reel it in. Just as you thought you had it out of the water a bit more would emerge. It was actually a bit scary. Having started off thinking it was a mackerel and then perhaps a large bass we ended up looking at something we did not even recognise. It looked prehistoric.

“I have never seen anything like it. Rob and I spent all night poring over fishing books but could not find anything that even resembled it.”

The fish took up a large space in the couple’s freezer while villagers debated what it was. Mr Herrings said: “People who have been fishing round here for years had not seen anything like it. No one knew what it was.”

Graham Hill, science officer at The Deep, an aquarium in Hull, said that he had never heard of another oarfish being caught off the coast of Britain. “It has won its reputation in marine mythology for its long, silvery body,” he said.

“It has a depth range of between 20 and 1,000 metres and is sub-tropical, so it’s not unfeasible they could survive in these conditions.”

The Natural History Museum in London said yesterday that it would be interested in preserving the fish in its permanent collection. Oliver Crimmen, curator of fish, said: “This is probably the most important thing to happen in the ichthyological world for some time.”

Unfortunately the oarfish has been cut up into steaks for the pot.

The king of herrings

The oarfish — Regalecus glesne — is sometimes known as king of herrings or ribbon fish. It has a silver body, bright red dorsal fin and mane-like crest behind the head. It is usually found deep in sub-tropical waters of Atlantic, Pacific and Indian Oceans and is classed as scarce. The last one seen in Britain was found in 1981 on a beach at Whitby, North Yorkshire. It has been preserved in the National History Museum. There is only one photograph of an oarfish in the wild, which shows that it swims vertically, propelled by its undulating dorsal fin. Its jelly-like flesh is unpleasant to eat, but the Cleveland one could make 373 6oz portions.

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