When Paul Garcia looks back at that hectic summer 31 years ago, he mostly remembers a lot of standing around, talking baseball with the lead actor and waiting to be called to the set.

For Lynn Murphy, that summer meant time in the Valerie N. towing boats, barges and shark cages across Island waters. And for Hershel West it was the summer his dog Chipper won him a speaking role in one of the biggest films of all time.

As movie buffs and the media descend on the Vineyard this weekend to mark the 30th anniversary of Jaws, memories from that summer of blood are flowing like, well, blood from the great mechanical shark's mouth. The film, widely considered the first summer blockbuster, was shot here over more than five months in 1974.

Starting today, the Martha's Vineyard Chamber of Commerce, with the help of Universal Studios, will recast the Vineyard as Amity Island, the tiny resort town terrorized by a great white shark.

In Edgartown, which stood in for downtown Amity, the signs are everywhere: The banner over Main street welcomes visitors to Amity Island, and just a few doors down Amity Hardware and the Amity National Bank are open for business. Shark images are everywhere, and menus in almost every Island restaurant feature a certain special seafood dish.

Jaws Fest activities are scheduled throughout the weekend. Highlights include autograph sessions with former cast and crew members like Lee Fierro and Bob Carroll; an outdoor screening of the film tonight at 7:30 at Owen Park in Vineyard Haven; and the Amity Island Ball at the Hot Tin Roof Saturday night (for a full schedule of events, see the Amity Gazette in today's edition).

But while the weekend features plenty of interaction with Islanders who played more significant roles in the movie, there are countless more who worked as extras or behind the scenes. For every Islander close-up, from Donald Poole to Peggy Scott to Dr. Robert Nevin, there were hundreds of others in the background. They sprinted out of the water, marched down Main street in Edgartown and raced to sea to hunt the great white menace.

"I had a role as an assistant harbor master, and I was in a boat scene with [Roy] Scheider, but most of my scenes were cut," Mr. Garcia recalled. "A lot of us extras just sat around waiting for our scenes. Sometimes we'd sit on the porch of the Colonial Inn and talk to Scheider. He was a very down-to-earth, real guy. All he wanted to do was talk about the Yankees."

Mr. Garcia, who had gone to acting school and had already been in a film, was cast after meeting Jeffrey Kramer, the actor who played deputy Lenny Hendricks. But despite the hours of preparation, Mr. Garcia can be seen for only a few seconds.

"I just remember it as a long, slow process," he said.

Being in the right place at the right time was the key for Deb Judd. A recent high school graduate when she came to the Vineyard in 1974, she had no idea that a major motion picture was being filmed. She and her friends, who were on a bicycle tour of the Cape and Islands, couldn't resist checking out the scene.

"We heard they were filming at State Beach, so we decided to hitchhike over," she said. "A limousine on its way to the beach drove by and stopped and picked us up. I don't know who was inside, and for all I know it could have been Steven Spielberg, but we were just excited to get there. Nobody knew who Spielberg was back then anyway."

Ms. Judd says she and her friends tried to get jobs as extras, but casting director Shari Rhodes turned them away. When the girls returned awhile later in bikinis, they were allowed on the set.

"We looked more the part the second time around," she joked.

For the next three days the girls lounged in between scenes of the beach stampede and the shark attack inside the pond. She remembers the weather was spectacular, the pay was decent and— perhaps most vividly — that the young man playing the lifeguard was adorable.

"He was a cute-as-a-button college kid," she said. "We threw our towels down right in front of the lifeguard stand, and that's where my attention was focused. I mean, what more could a 17-year-old girl on vacation ask for?"

But while her memories of those three days are sharp, Ms. Judd admits that she has yet to find any proof of her participation. Some of the underwater shots of legs may be hers. She can't be sure.

"I have seen this movie I can't tell you how many times, and I can't really say I have seen myself yet. I look for the bathing suit I was wearing, I look for my hair, I look for anything, but it just isn't there. Sometimes I think I see myself, but even slowing down the movie or pausing it doesn't really help.

"I believe I am in there somewhere, and that's all that counts," she added.

As first mate to Robert Shaw's shark fisherman Quint, longtime Menemsha fisherman Hershel West had a bit speaking part. But it didn't start out that way. Mr. West was hired first to simply drive boats in Edgartown harbor; he landed the part of Quint's sidekick only after an altercation involving his poodle, Chipper.

"If I went somewhere, the dog went with me, always," Mr. West explained. "If the dog didn't go, I didn't go. Someone in Edgartown said the dog had to go, and I said that I would leave, too."

His stubbornness and devotion to his dog caught the eye of Mr. Spielberg, who approached Mr. West about the new role. On his first day on the set, a scene at Quint's fishing shack in Menemsha, he arrived clean shaven and in his finest clothes — not exactly what the young director had in mind.

"They sent me home and told me to put on what I was wearing before," Mr. West said.

"Spielberg was very good. He told everyone, ‘Use your own sayings.' So when we were about to go out in the boat, my line to Quint was ‘I quit — I ain't goin' out in that slab.' But they took it right out. Either way, the dog got the job. I didn't."

Mr. West also recalled Chipper almost biting Mr. Shaw when the two were rehearsing a scene in which Quint knocked over a chair in anger.

"Boy, Chipper went right after him," Mr. West said with a chuckle. "Spielberg loved it, but the cameras weren't on. That dog was very protective of me. Boy, it scared Shaw, too."

Lynn Murphy never had an on-screen role, but the film certainly owes a large part of its success to him.

The owner of Menemsha Marine Repair was hired as chief mechanic, technical consultant, shark operator and supervisor for a project that grew increasingly complicated every day. The mechanical shark malfunctioned. The elaborate trolley system used to make it swim rarely worked. The delays piled up.

"We were spending money like drunken sailors to make that shark work," Mr. Murphy said. "I remember when [Richard] Zanuck and [David] Brown [the film's producers] showed up and all of a sudden it was sink or swim. If that shark didn't work, it was over."

"That was wild, seeing Zanuck and Brown walking down Main street in Edgartown," Mr. Garcia said. "They were the biggest things in Hollywood at the time. You knew when they showed up, the film must have been in trouble."

As the pressure grew, so did Mr. Murphy's responsibilities. He was in charge of towing the 20-foot shark, its unwieldy wooden cage and Quint's boat, the Orca, to different shooting locations. He also was invaluable when it came to running the air compressors that eventually made the mechanical shark work.

And on some days, he even played the role of babysitter.

"A lot of the time it was ‘hurry up and wait,' with nowhere to go," he said. "I got to know Shaw's young kids and would take them out in one of the little boats that had a small outboard motor that you had to pull to start. One day they asked me if they could drive the boat. These kids were really young, so I told them if they could start it, they could drive it. Well, I couldn't believe it when they pulled on that thing and it started right up," he said.

"So I let them drive the boat."