Bluefin tuna — the center of a highly lucrative commercial fishery and heated controversy about overfishing — will not be listed as an endangered species, the National Oceanic and Atmospheric Administration announced last week.

“NOAA is formally designating both the western Atlantic and eastern Atlantic and Mediterranean stocks of bluefin tuna as species of concern under the Endangered Species Act,” a press release that accompanied the decision said.

A petition to place the fish on the endangered species list came from the Center for Biological Diversity based in San Francisco and Tucson, a year ago. The center also sought and failed to place white marlin on the endangered species list in 2002.

Catherine Kilduff, an attorney for the center, said last week that the decision on bluefin tuna was not based on the merits. “I am terribly disappointed. I think it was politically motivated,” she said.

Ms. Kilduff said her organization will continue to raise awareness of the plight of the fish by urging consumers to stop eating bluefin tuna.

“Unfortunately, due to its popularity as sushi, its high commercial value and its habit of crossing international boundaries, the bluefin tuna is being severely overfished and is at risk of extinction. Since 1970, western Atlantic bluefin tuna have declined by more than 80 per cent due to overfishing,” said a statement on the center’s Web site.

The request for the endangered species designation was spurred in part by the huge oil spill in the Gulf of Mexico a year ago. The gulf is a primary spawning ground for western Atlantic bluefin tuna.

“NOAA is concerned about the status of bluefin tuna, including the potential effects of the Deepwater Horizon BP oil spill on the western stock of Atlantic bluefin, which spawns in the Gulf of Mexico,” said Jane Lubchenco, under secretary of commerce for oceans and atmosphere and NOAA administrator, in a press release.

The National Marine Fisheries Service report, prepared by the review team considering the endangered status, dated May 20, said the possible effect of the oil spill on the health of tuna stocks was minimal. “. . . Independent projections with two different types of models show that a 20 per cent reduction in the 2010 year class will likely result in less than a four per cent reduction in future spawning biomass,” the report said.

Vineyard fishermen have their own concerns about the plight of the bluefin tuna. Jonathan Mayhew, a longtime commercial fisherman out of Chilmark, said he remembers watching his father harpoon a giant bluefin tuna in the 1960s between Gay Head and Noman’s Land, and he remembers seeing schools of tuna chasing sand eels just south of Noman’s Land in the 1980s. Mr. Mayhew said he is certain that today bluefin tuna are being overfished on the eastern side of the Atlantic Ocean. And severe overfishing on one side of the Atlantic will influence stocks on this side, fisheries scientists say.

Joe Re, an Oak Bluffs tackle shop owner, said commercial and sport fishermen have to go a good distance these days to find bluefin tuna. Most of the tuna fishing is done off Great South Channel, southeast of Chatham, Mr. Re said.

A 400-pound fish can be worth thousands of dollars if it is quickly shipped by air to Japan.

But Tom Furino of Edgartown, who formerly operated a bluefin tuna buying market in Gloucester, said he got out of the business when the fish moved toward Canada.

Last week Alex Friedman of Edgartown caught a bluefin tuna. Mr. Friedman said he and his crew caught the 230-pound fish in Cape Cod Bay. His mates are Chris Jones of Chilmark and Sean Egan of Ridgefield, Conn, and Menemsha. Mr. Egan hooked the fish. Mr. Friedman said he did not know whether the fish would be flown to Japan for the sushi market, but he said he believed it was the first bluefin tuna of the season. He also said he believes adequate protection is in place.

“I have been concerned in the past about bluefin tuna. But I feel the strict regulations that Canada and the United States have implemented in the last 20 years have really paid off,” Mr. Friedman said. He said new rules include the use of so-called weak hooks, breakable hooks that will reduce the unintended catching of bluefin tuna in the long-line fishery for swordfish.

Mr. Friedman said restrictions in waters around the Vineyard, including a 73-inch minimum size and boat trip limits for commercial fishermen, also protect fish. Recreational fishermen have a minimum size limit of 27 inches.

National Marine Fisheries Service records show that the number of bluefin tuna have dropped significantly over the decades. Dr. Clay Porch, division chief with National Marine Fisheries Service Southeast Fisheries Science Center, said stocks dropped as much as 80 per cent from the early 1970s to the late 1970s. Incremental improvements have followed. “We are still concerned,” he said. There are some positive signs he said, including a good mix of age groups, although scientists would like to see more giant females.

Bluefin tuna are overseen in the Atlantic by the International Commission for the Conservation of Atlantic Tunas.

Ms. Kilduff said her center has not yet decided what its next step will be in the quest to protect bluefin tuna but they have a Web site to promote the boycott: