Oyster growers are as competitive as they come. “Insanely competitive,” according to Bob Rheault. As president of the East Coast Shellfish Growers Association, Mr. Rheault also encounters cultivators of clams, quahaugs and mussels, but none rivals the oyster farmer for competitive spirit.

“We all have this conviction that our oyster tastes the best,” said Mr. Rheault, an oyster farmer himself, “and, if you don’t have this conviction, you probably shouldn’t be in this business.”

So Mr. Rheault this year decided to settle the score.

As part of the 100th anniversary of the annual meeting of the National Shellfisheries Association, the shellfish growers association has assembled a panel of nine judges to rank 20 different varieties of the eastern oyster. The competition will take place at 7 p.m. Monday, April 7, at the Westin Hotel in Providence, R.I.

Two growers from the Vineyard, Jack Blake of Sweet Petites and Roy Scheffer of Katama Bay Oysters, are among the 20 oyster farmers who will compete.

“A lot of people say they’re the most wonderful oysters they’ve ever had,” Mr. Blake said this week as he readied his oysters for the lineup. “I’m kind of biased. I really am, but you won’t know until you try them.”

The oysters will not be judged on taste alone, however. Mr. Rheault has assembled chefs from around the country (one was a 2007 nominee for the James Beard Foundation Best Chef award, another has earned the nickname Bishop of Bivalves), seafood buyers, the chair of the culinary arts college at Johnson & Wales University and the author of A Geography of Oysters, to taste the oysters. According to a scorecard leaked to the Gazette this week, the shellfish will receive good marks for shuckability, a strong briney odor and a good meat-to-shell ratio. Points will be stripped for mushy texture, flawed appearance, or a taste of “wet burlap.”

Rick Karney, director of the Martha’s Vineyard Shellfish Group, thinks the Vineyard oysters will hold their own among the competition. “They had a beauty contest competition over on the West Coast a couple years ago. Jack’s won the most beautiful East Coast oyster,” he said. “I’ve got a lot of hope that they’re going to score really well.”

“It’s something I’ve wanted to do for years,” Mr. Rheault said. As a grower, he has his own theories as to why certain oysters taste better than others, but he wanted a definitive answer. After the judges pass their judgement Monday, samples will be sent to scientists at Brown University. The scientists will then analyze the salt and mineral content of each oyster to better understand the mystery behind the different tastes.

“I’m really proud of them,” Mr. Karney said of the growers. Mr. Karney helped start the Vineyard oyster farming program less than ten years ago. “They were both really interested when we started the program right from the beginning,” he said of Mr. Blake and Mr. Scheffer. “It’s really neat to see how far they’ve come with it.”

The winner of the competition will be announced Monday evening following the tasting. As for prizes, the pickings are slim. “Just bragging rights,” said Mr. Rheault. “That alone is worth a lot.”

Mr. Blake’s Sweet Petites oysters are available at Offshore Ale Co. and the Net Result. Come springtime, they will grace the menus at L’Etoile, Catch at the Terrace and the Coach House restaurant, all in Edgartown. Mr. Scheffer’s Katama Bay Oysters can be found at Edgartown Seafood and, come spring, will be available at Larsen’s Fish Market in Menemsha.