Jaws was introduced to the world 50 years ago, on June 20, 1975, but for Vineyarders the movie was already part of local legend. Filming began on the Island in May of 1974, with Islanders being cast as extras and a few lucky souls earning larger roles.

For everyone who was on the Vineyard then, the movie is a time capsule of their youth and to a way of life here that now mostly exists only in memory.

The Vineyard had become part of the national consciousness in 1969 during the tragedy of Chappaquiddick, following the death of Mary Joe Kopechne and the media circus surrounding Sen. Ted Kennedy’s involvement. But now it was a main character in a movie — and not just any movie. On opening day, Jaws played on 464 screens in the U.S. and Canada, grossing a record $7 million during its first weekend. As the summer continued, screenings were added and long lines were commonplace, especially on Circuit avenue in Oak Bluffs.

William Caldwell covered the opening for the Vineyard Gazette.

Vineyard extras take part in legendary scene with Quint dragging his nails down the blackboard. — Edith Blake

“Both screenings, in the Island Theatre, Oak Bluffs, at 7 and again at 9:30 p.m., have been sold out for a week to audiences that will total 1,000 and pay premium prices ($10 and $15) to have the wits scared out of them,” he wrote in his June 20, 1975 byline. “The showings, sponsored as a benefit by the Martha’s Vineyard Hospital auxiliary, will net some $9,500 to the hospital’s support, said Curtis Collision Jr., director of its sustaining fund.”

The film’s success was by no means a given, especially during the difficult shoot. In the documentary Jaws @ 50, which is premiering this weekend on the Vineyard, director Steven Spielberg revealed that he thought he would be fired at any moment during production, as filming was delayed and costs continued to rise. Back in Los Angeles, he said he often had to hide away and weep, he was so distraught.

But history judged him much more favorably, as Jaws remains as popular as ever, with fans from around the world headed to the Vineyard this weekend to walk in the footsteps of legends. A long list of events are planned, from the Jaws @ 50 documentary screening to a day-long fan festival put on by the Vineyard Gazette at the Martha’s Vineyard Museum. Jaws memorabilia is available in nearly every store, and the movie with the original live score will be performed at the Winnetu Oceanside Resort.

The local legends in the movie were just regular Islanders in the spring of 1974 when they responded to an open casting call for extras. A year later they had morphed into movie stars, smiling, grimacing or being chewed up on the big screen.

Chris Rebello played Chief Martin Brody’s oldest son. Mr. Rebello died much too young, of a heart attack at age 38, but lives on forever thanks to his role in Jaws, telling his movie father Roy Scheider he got bit by a vampire, or treading water in shock as the great white shark swims by him.

Bruce was a very moody actor. — Edith Blake

Jonathan Filley was a lifelong Chappy summer kid when he got the part of Tom Cassidy, who in the opening scene is looking for a one-night stand with Chrissie Watkins, the first victim played by Susan Backlinie. The character never got past first base, though, as Chrissie swam off into the jaws of a shark while Cassidy passed out on the beach. But that failed romantic encounter turned into a lifetime of love for Mr. Filley who, inspired by his experience on set, went into the film business and continues to have a successful career as a film producer.

“The circus came to town, and I ran off with the circus,” Mr. Filley told the Gazette.

Jonathan Searle is now the chief of police in Oak Bluffs but in the film he is a young prankster, sneaking up on swimmers while wearing a fake fin. He also had a role in an early scene playing in drum and bugle corps.

Last week he got together with some of the other third graders from the Edgartown School who also starred in the scene, including Tom Sawyer.

In an interview with the Gazette, Mr. Sawyer said watching the movie transports him back in time.

Steven Spielberg was 26 years old when he took on Jaws. — Edith Blake

“It brings you back to your childhood because these were all very prominent members of the town at that time,” he said. “You see all these Island people that are no longer alive...even if it’s a quick shot of them, it’s like, oh, I remember.”

But it wasn’t all fun and games as Islanders discovered how mundane and grueling a film shoot can be. Writing in 1974, Edith Blake revealed what even the extras had to endure for their $40 per day.

“The 400 waded out into waist high water (which seemed to be waist-high regardless of whether the tide was high or low) and accompanied by the most outlandish moans, hoots and groans sank slowly (ever so slowly) to their knees; thus portending they were up to their necks in cold water (definitely not hot) only to get chased right back up on the beach by a shark. This did not happen once, or twice, but every five minutes with a regularity becoming only to trans-Atlantic shipping. ‘Be exhausted,’ said the electrified voice. That was easy. Who needed to be told to be exhausted and breathless after a sprint in ice water?”

And yet all the local actors, either cast in roles that had actual names and speaking parts, as extras who are seen for a second or two onscreen or banished to anonymity on the cutting room floor, echoed a similar refrain: Jaws for them is much more than a movie. Rather, it is a living testament to the friendships formed during the movie’s production, and to a time when the Vineyard was still a quiet backwater and not a big screen star.

As Edith Blake so expertly predicted in 1974: “So, batten down the hatch­es, along with the trips to Dike Bridge and the County of Dukes County Court House there will now be tourists touring where Jaws was made. It’s something people will jaw about for a long time.”

Addison Antonoff, Gwyn Skiles and Louisa Hufstader contribute reporting.