First it was blue mussels. Now a harvesting ban has been extended to most shellfish.

Yesterday, the Massachusetts Division of Marine Fisheries announced a ban on the taking of shellfish, including clams, from the Manchester town line to the New Hampshire border. Only sea scallops, lobsters and crabs are excluded.

A bloom of red tide, an algae toxic to humans, has pushed toward shore in recent weeks and had already led this week to a ban on harvesting blue mussels.

Despite the fact that the ban covers the epicenter of shellfish harvesting in Massachusetts, local restaurants are not worried, saying they'll get their clams elsewhere. Once fried, they become Cape Ann's favorite summertime dish.

"Basically we will be getting our clams from up north, New Hampshire and Maine," said Eian Woodman of Woodman's of Essex. "We want to ensure customers we have plenty of healthy clams. Everything we serve is safe to eat."

Officials at Woodman's said the price of a fried clam plate is not automatically affected by a red tide bloom. It depends, as always, on supply and demand. As long as there are clams in areas not affected by red tide, the market will not be altered, Woodman's officials said.

Terry Cellucci, of JT Farnham's in Essex, said the business already has clams on order that are shucked for the weekend.

"Beyond the weekend, we will be looking farther north if necessary," Cellucci said. "We want to ensure customers all our clams are safe."

The state Division of Marine Fisheries yesterday found high levels of red tide in samples from the area and ordered the ban. The ban is declared, the fisheries division said, when toxicity levels in shellfish approach the danger point.

Division biologist Jeff Kennedy said the appearance of red tide was later this year than is typical. Red tides "bloom" when the billions of microscopic phytoplankton plants present in every drop of coastal seawater get just the right conditions of sunlight and nutrients and multiply uncontrollably, giving the water a red cast.

Alexandrium tamarense, the organism that causes toxic red tides in New England, is harmless to bivalves, but they accumulate high levels of its toxin as their systems filter seawater for nutrients. Humans who ingest high concentrations of the toxin can suffer paralytic shellfish poisoning.

Kennedy said he doubted the new bloom and ban would match "the big one," which halted clamming and harvesting of all shellfish from Maine to south of Cape Cod for many weeks in 2005. Another major bloom, less widespread and long-lasting than 2005's interrupted shellfishing last year.

In past years, the region's restaurants serving clams resorted to imports from southern New England, the Middle Atlantic states and Canada when supplies of pre-red tide shellfish were exhausted.

The bloom typically forms offshore in the Gulf of Maine and is pushed into the estuarial beds by easterly and northeasterly winds.

Correspondent Lauren Mears contributed to this report.