On New Year's Eve each year, thousands line up at fish counters across Hawai'i to buy blocks of raw tuna, hoping that eating it will bring good luck and prosperity in the new year. This year, the long tradition may get a little more difficult to observe.

For the first time, federal regulators are expected to prohibit the catching of bigeye — Hawai'i's favored tuna variety — in waters west of the Islands once the fishermen hit their annual catch limit. They're on course to do that around the first or second week of December.

The potential for a shortage has produced anxiety here among consumers, fishermen, wholesalers and retailers, leaving them to wonder if they'll be able to get hold of the tuna, or 'ahi.

"We may not have as much fish. In terms of quality, I don't know how it's going to compare to what we normally have," said Brooks Takenaka, assistant general manager at United Fishing Agency, which runs Honolulu's fish auctions. "Those are questions nobody has any answers to right now."

The tradition began with Japanese immigrants who arrived here a century ago to work on the sugar plantations but has since spread to the numerous other ethnic groups. The custom in Japan is to eat tai, or sea bream, for good luck. But this fish isn't found in waters around Hawai'i, so the immigrants substituted 'ahi.

Clarence Gonsalves said he's never had a New Year's without 'ahi before. "It's a tradition in Hawai'i. No matter what the price is, you'll have it," said the 76-year-old retired supermarket meat cutter. "We've never run out of it."

This year, the outlook is not so clear. While everyone agrees there will be tuna on the shelves, they're not sure how much or what kind. That's because those responsible for managing fish stocks believe fishermen must curtail their bigeye catch to protect the species, which is prized around the world for sashimi.

Environmentalists say people are catching so much 'ahi in the Western Pacific that the fish are close to the point where they won't be able to reproduce fast enough. The situation is already dire in the Eastern Pacific. Last December, the Western and Central Pacific Fisheries Commission, which regulates commercial fishing from Indonesia to Hawai'i, concluded the bigeye catch must be slashed 30 percent in its waters.

To do their share, the 130 boats in the Hawai'i-based longline fishing fleet must slice their bigeye yield by 10 percent compared with what they caught in 2004. That means they're allowed to take only 3,763 metric tons in 2009. As of early November, they had already caught 3,119 metric tons.

The National Marine Fisheries Service is monitoring the fleet's logbooks to keep track, said Tom Graham, a fisheries policy analyst with the National Marine Fisheries Service in Honolulu. The agency will give fishermen seven days' notice before it prohibits taking more bigeye, Graham said.

Hawai'i's longliners hope to limit any market upheaval by staggering their return to port once the fishery is closed, said Sean Martin, Hawaii Longline Association president. This will prevent all their tuna from landing on the market all at once.

"Coordinating fishermen is kind of like herding cats. But we're trying to coordinate our production side to continue to provide some consistency to the supply," said Martin, whose company, POP Fishing & Marine, operates five longline boats.

Martin noted longliners will still be allowed to fish in waters east of Hawai'i. The Hawai'i-based fleet's annual catch limit in this area is 500 metric tons this year and it's not close to being met.