Devon Metters could have weighed in one of the largest shore-caught false albacore of the Martha’s Vineyard Striped Bass & Bluefish derby’s second day Sunday.

He caught a 44-inch bluefin tuna with his bare hands instead.

“I caught a big albie in the morning, definitely weighable,” Mr. Metters recalled on Monday. “I wanted to weigh it in, and I thought, no, I’m going to wait.”

Hours later, Mr. Metters was standing on the shore of State Beach with no false albacore but a bloodied foot, a real bluefin tuna and a story for the ages — his place on the derby’s end-of-day leaderboard momentarily lost, his standing in Vineyard fishing legend permanently gained.

“It was probably one of the craziest things to happen, and probably ever will happen, to me,” Mr. Metters said. “Just mind-blowing.”

The 22-year-old Island-born fisherman was chasing the derby fish with his friends Thomas O’Shaughnessy and Curtis Farrell just east of the little bridge on Beach Road Sunday morning when they saw a fin circling close to shore, in shallow waters approximately two feet deep.

Mr. Metters, who works his day job on a Menemsha charter boat, and Mr. O’Shaughnessy, went up to the fin for further inspection.

“We thought it was a brown shark, which are pretty common around here,” Mr. Metters said. “When we went up to get a closer look, I’m like, holy . . . that’s a bluefin tuna.”

A species of tuna that can weigh up to 1,500 pounds, Atlantic bluefin are a deep sea fish almost exclusively targeted hundreds of miles off the coast. It’s exceedingly rare to see them in the Vineyard Sound. It’s even more uncommon to see them within two feet from shore. Mr. Metters knew he had the chance of a lifetime.

“To see them in water like that is unheard of,” Mr. Metters said. “My buddy said, you have to catch that with your hands.”

The tuna, which appeared distressed, circled around Mr. Metters a few times, giving him a fight the way only a 40-pound bluefin can. He thrashed in the water before gripping the tuna’s back tail and wrestling it to shore.

“It’s a powerful fish,” Mr. Metters said. “It was like grabbing on to a jackhammer.”

An experienced fisherman, Mr. Metters said that he only keeps his catch in rare circumstances, particularly if the fish is injured or unhealthy. With the bluefin struggling, Mr. Metters decided to bleed it immediately, and rushed over to Our Market to grab ice.

Although it is technically illegal to target Atlantic bluefin tuna from shore, according to fishing law, Mr. Metters said he contacted NOAA Fisheries after the catch and regulators said that because of the circumstances, he was all in the clear.

“They said said congratulations on the story, and maybe you did the right thing,” Mr. Metters said.

It was only by the time Mr. Metters got home, covered in what remained of the tuna, that he’d realized that he sliced his foot in the water.

“I was flying on adrenaline, and taking off my clothes and boot, I realized it was my own blood,” Mr. Metters said. “It was worth it for the story. Just another scar.”

Mr. Metters had a few theories about why the tuna had nestled itself so close to the coast. While the fish could have been sick, Mr. Metters thought it was more probable that it had been previously caught in a bluefin fishing tournament held off Nantucket last weekend, and released into the water with injuries.

After fileting the fish, Mr. Metters also said that he examined its body and stomach, not finding any signs of illness.

Earlier in the morning, Mr. Metters said he had been kicking himself about not weighing in the albie. In a sport known for its often fruitless cliches about patience and perseverance, he was thrilled to finally finish the day with a much bigger prize.

“If I weighed in the albie, I wouldn’t have caught the tuna,” Mr. Metters said. “I’ve been fishing my whole life, just trying to chase the dream of winning the derby. And I guess what I felt yesterday is maybe what it feels like to win the derby. I won my own derby.”