Summer at Cape Cod – cue the Jaws music

instructors have stopped offering lessons and many parents are ordering their children not to swim out of their depth.

Between July and the first week of August at least 59 beaches have been closed because of shark sightings around Cape Cod, 40 of which were in the first seven days of this month.

Lifeguards equipped with new first-aid kits that include tourniquets to staunch heavy bleeding now fly purple shark warning flags at all times.

The catalyst for these changes came last September when a great white shark killed Arthur Medici, a 26-year-old Brazilian boogieboarder, about 10m from the shore at Newcomb Hollow Beach on the Atlantic-facing east coast of Cape Cod. He suffered serious leg injuries and died in hospital.

It was the first fatal shark attack off Massachusetts since 1936 and took place less than 80km from Martha’s Vineyard, where the 27-yearold Spielberg directed his breakthrough film 44 years ago and put millions worldwide off a dip in deep waters.

This summer researchers have identified at least 300 sharks lurking off Cape Cod, most of them sighted off beaches facing the open Atlantic, sometimes very close to shore. ‘‘We’ve seen sharks as big as 15 feet in less than 5 feet of water,’’ said Megan Winton, a research scientist with the Atlantic White Shark Conservancy.

A state researcher who tags great whites said that he had never had a busier July.

The sharks are drawn in by the area’s thriving population of grey seals and are, like their prey, protected by state and federal laws that ban hunting of ocean mammals.

The conservation success story now carries a human consequence. For Cape residents, many of whom grew up swimming and surfing regularly in the same stretches of water where the sharks now hold sway, the threat is palpable.

‘‘We’ve been bullied out of the water by the sharks,’’ said AJ Salerno, who lives in Eastham, 16km south of Newcomb Hollow Beach.

– The Times