In an effort to lower nitrogen amounts in Sengekontacket Pond, Edgartown and Oak Bluffs are embarking on a yearly project to grow oysters in the Major’s Cove area of the pond.

In Edgartown, shellfish constable Paul Bagnall told selectmen Tuesday that the shellfish committee is proposing spending $24,000 on 250,000 oyster seed for the pond. The original plan was to spend $48,500 on 500,000 oysters, but the amount was reduced because of the number of articles submitted for town meeting.

Mr. Bagnall said the labor would be provided by the shellfish department and volunteers. Edgartown oyster farmer Jack Blake provided the town with a test cage last summer and fall, and Mr. Bagnall told selectmen in a letter that growth and survival were good for the oysters.

Neighboring town Oak Bluffs has proposed a similar project to the Community Preservation Committee, shellfish constable David Grunden said Wednesday, with that town going ahead with a plan to grow half a million oysters.

With a survival rate of 80 per cent, 500 bushels would be available for harvesting by family shellfish permit holders, Mr. Bagnall told selectmen.

Slightly less than $50,000 in Community Preservation funds would finance the project, Mr. Grunden said, though the Community Preservation Committee hasn’t decided on what projects to support yet.

A state study released in September showed that Sengekontacket has nitrogen levels above acceptable levels, with Major’s Cove having some of the highest levels in the pond. An adult oyster can pump and filter 20 to 50 gallons of pond water per day, according to a 2009 report by the Martha’s Vineyard Commission.

The oysters would be held in captivity for the first year of their lives in an upweller, and then put into bags in racks and placed on the bottom of the pond, Mr. Grunden said. In their second year, they would eventually be available for recreational shellfishing.

Mr. Grunden said Oak Bluffs plans to make this an annual project, with 500,000 oysters planted each year.

With town meeting funds not available until July 1, Mr. Grunden said he did not expect the program, if approved, to start until the spring of 2014.

This isn’t the first time Oak Bluffs has grown oysters in Sengekontacket, Mr. Grunden said. “They grow well and taste great,” he said, but high salinity and predators mean the young don’t often make it.

“We’ve got to do something; there’s heavy nitrogen in the pond,” Mr. Grunden said. “Shellfish will help us.”

In other business before the Edgartown selectmen Tuesday, Edgartown will become a cruise ship port this summer. Selectmen approved a proposal to allow American Cruise Lines to come to Edgartown 20 times between May and September.

Harbor master Charlie Blair told selectmen that the cruise company offers seven to eight-day cruises, and has previously stopped in Vineyard Haven and Oak Bluffs. The largest of the company’s three boats holds 100 passengers.

He said the company would anchor outside the harbor and bring passengers to the harbor on the ship line’s own launch, with the ship arriving Tuesday night and leaving Thursday morning at 2 a.m. Mr. Blair said it would be a good deal for May, June and September, and though it might be a little tight in July and August, it was doable and wouldn’t put a strain on the harbor department.

“I think it’s terrific, great for Edgartown and Edgartown businesses,” selectman Arthur Smadbeck said.

In other harbor news, Mr. Blair said the New England Cat Boat Association would be holding an event in the harbor on the weekend of June 7, with up to 50 cat boats coming to the harbor.