And, 4000 miles away, terrified swimmers fled the sea after a huge fin was spotted by holidaymakers enjoying the hottest day of the British summer so far on the beach at Herne Bay, in Kent.

The 68-year-old victim of the North Carolina attack was swimming in waist-high water on the Outer Banks’ Ocracoke Island on Wednesday when he was grabbed – possibly by a gray shark of around six to seven feet in length. He was dragged beneath the surface and suffered bites to his rib cage, hip, lower leg and both hands. He was flown to hospital but was still conscious and talking.

“There was a big trail of blood from the water to the sand,” said witness Stephen Lee, talking to CNN. “There’s still people here and some people have gotten back in the water, and the park rangers are just now trying to vacate the area.”

An 18-year-old boy was taken to hospital in a critical condition after being bitten on the Outer Banks on Saturday. In all, seven people have now been attacked in three weeks. On one day a 13-year-old girl and a 16-year-old boy both lost their left arms following separate attacks just 90 minutes apart at Oak Island.

George Burgess, director of the Florida Program for Shark Research, said factors such as warmer water and drought conditions could be contributing to the rash of attacks. He told CNN drought conditions created an environment along the shore where high salt levels attracted more fish – including hungry sharks.

“This is a situation that we can’t ignore, as we’ve had a number of attacks that are serious within a short period of time,” said Mr Burgess. “There’s something going on there, there’s no doubt about that. It’s a perfect storm of environmental and biological variables, as well as human activity.”

Meanwhile, in Kent, swimmers stamped from the North Sea in panic after the fin was spotted protruding from the water around 25 yards from shore at Herne Bay, near Canterbury. Species seen off the Kent coast include the huge but harmless basking shark, which grows to around 25 feet in length but feeds exclusively on plankton.