Peter Dent spotted the six-foot (1.8 meter) fish weighing 58 pounds (26.3 kilograms) caught in his salmon net Monday as he fished less than a mile (1.6 kilometers) off the coast of Newbiggin-by-the-Sea, Northumberland.

He brought it into Blyth, Northumberland, where it was stored on ice before being sold to a local restaurant.

"It's the kind of thing you see in Spain, but not here," said Mark Watson, a trader with Blyth Fish.

Fishing commentator Sam Harris, 73, said it was the first time he had heard of a swordfish being caught in chilly British waters.

"This fish is two or three thousand miles off course," Harris told the domestic Press Association news agency.

"It just proves how the water temperature is hotting up. It is absolutely amazing, it shouldn't be up here," he said.

"They are found in the North Atlantic, the Pacific, the Mediterranean, but certainly not in the North Sea."

Harris said divers have told him that the North Sea's temperature has risen greatly in recent years. He added that the swordfish was "in 100 percent good condition, probably from feeding on the huge shoals of mackerel here."