CHINCOTEAGUE, Va. - The only oyster that tasted anywhere near like a real Chincoteague during the 30th running of the oyster festival here was the one I had over Tommy Mason's kitchen sink at the Waterside Motor Inn.

A real Chincoteague has an extraordinarily salty wallop and a crisp, dry finish - a flavor profile very much coveted still in the raw bars of Philadelphia and celebrated on this ocean-facing scrap of barrier island each Columbus Day weekend.

But times are so tough in the seaside oystering beds off Chincoteague (pronounced SHING-ko-teeg by the natives) that this year there weren't nearly enough local oysters to feed the 2,700 visitors who lined up at the festival's cook sheds at the Maddux Family Campground.

The Chamber of Commerce didn't even try. (One officer said the oysters they were serving came from Connecticut. But I learned later that even he didn't have the full story.)

Chincoteague hasn't had to endure the runoff and pollution problems that have added to the oystering woes of the nearby Chesapeake Bay. But its oysters have been so decimated by two protozoan parasites (MSX and Dermo) that locals fear they'll soon be left with a boutique shellfishery - if any at all.

The big bronze-shelled oyster that Tommy Mason opens with his penknife in the motel where his shucking house once stood is his vision of a savior-in-waiting, a species native to Asia formally called the ariakensis or the Suminoe or simply "the Japanese" oyster.

For the moment, it is being raised experimentally in wire cages suspended in the tidal waters, rendered sterile to prevent reproduction. It has grown fast, stayed healthy - it resists the parasites - and absorbed a good deal of the Chincoteague's signature flavor. (It is growing in the same broth, after all.)

But as the struggle is joined here over the possible unintended consequences of turning loose a non-native oyster - might it wipe out the original species for good? - and how long to study the issue, scientists taking an even longer view have raised another alarm.

The fact is that the parasites afflicting Chincoteague once were unknown outside the milder Southern waters off Louisiana and Texas. As global warming has inched up the water temperatures in these parts, the parasites - which like warmer, salty conditions - have found a new haven.

"Chincoteague has two strikes against it," says Eric Powell, a Rutgers University shellfish biologist. "It's saltier, and now it's warmer."

In the Delaware Bay, the same bugs invaded in 1990, destroying oystering for five years until researchers called for transplanting shell beds known as clutch farther north in the bay.

Harvests have climbed back to more than 50,000 bushels a season, modestly good news though a far cry from the 500,000 bushels some think could be taken with more state transplanting assistance - and a pittance next to the two million bushels that schooners hauled into Bivalve, N.J., 75 years ago.

In fact, it was Delaware Bay oysters (sometimes called Bennies) that the unsuspecting crowds at the Chincoteague festival were consuming fried and on the half shell and in their fritters.

It pained Chincoteague waterman Mike McGee, who supplied them. His is the last shucking house standing (out of 13), down from 50 shuckers to 10.

It's a shame, he says, because "we have the freshest, cleanest water around, even cleaner than 50 years ago now that the oyster houses aren't polluting."

The greater shame, of course, will be that after enduring the same period of rapacious overfishing that turned New Jersey's sturgeon ports into ghost towns a century ago, and after cleaning up its water, Chincoteague and its proud heritage buckle under the assault of distant smokestacks and tailpipes.

Anyone who thinks climate warming is unproven or far away need only visit for a few hours to get a taste of the devastation it has already caused.

It is a bitter taste, nothing like the briny Chincoteague of legend - and certainly nothing to celebrate.