NEW YORK (CNN/Money) - A wise man defined the good life as a crisp Sauvignon Blanc on a warm summer's night, with a dish of drawn butter and a steaming lobster to dip in it.

If that menu sounds tempting, you'll have to hurry to enjoy it -- and not just because it's September. America's bountiful lobster catch may soon dwindle. If the scariest forecasts come true, it could eventually decline by as much as 50 percent.

It's a best-of-times, worst-of-times scenario. For the past few years, the lobster industry has experienced a roaring boom in some places, simultaneous with a staggering decline elsewhere.

In the southern parts of its natural habitat, the lobster (Homarus americanus) has been disappearing rapidly.

But up north, along Maine's famously craggy coast, harvests have been far more robust than ever seemed possible. And despite annual pessimistic yield predictions, they're still pulling up full traps.

No food defines casual sophistication quite like lobster, at least since the Kennedys served them in the White House. Back then, Maine lobstermen caught about 20 million pounds a year.

The catch rose steadily, though incrementally, until the 1990s. Then suddenly, harvests began getting much, much larger.

"Over the last 10 years, the lobster catch has tripled," notes Robert Bayer, executive director of the Lobster Institute at the University of Maine. "Nobody really knows why. It could be the demise of predators like cod and haddock, or because of variations in water temperature."

In 2002, more than 63 million pounds were pulled out of Maine waters, worth about $211 million at the wholesale level. The yield fell back a bit in 2003, but remained historically huge.

"Maine still has a very healthy stock," says Bayer.

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Lobstering is no carefree business, even in heady times. A big, fully loaded lobster boat can cost $150,000 or more to outfit, and as much as $200 a day to operate. A single trap costs about $75, including the rope and buoy.

Besides the expense, it's physically grueling, sometimes dangerous work. But an experienced lobsterman owning his own boat can gross $100,000 or more during a 9-month season.

There are about 7,500 holders of commercial lobster licenses in Maine, who maintain more than 3 million traps, according to the state's Department of Marine Resources. And younger people are reportedly entering the business, causing small but noticeable population spikes in formerly desolate regions.

Everybody's making money in the boom, from the guy packing coolers for tourists to the big food processors in Canada, who buy some 60 percent of the harvest at prices of $3 to $4 a pound.

Flush with cash, you might think these are easy, happy days for Mainers. It's more complicated than that.

That's because other, smaller lobstering regions -- Massachusetts, Rhode Island, Connecticut and Long Island -- are facing a crisis.

"The catch everywhere south of Cape Cod has encountered extreme difficulty," says Lewis Incze, senior scientist at the University of Southern Maine.

Since 1999, New York's catch is off 75 percent, while both Connecticut's and Rhode Island's have been more than cut in half. Statewide figures from Massachusetts haven't been quite that bad, though certain areas have shown equally alarming dropoff rates.

No single factor explains the decline, but sickness and ecological change are among the culprits.

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A mysterious bacterial shell disease began in New York five years ago, then spread northward, decimating populations. As a further threat, slightly warmer waters seemed to bring new predators into lobster habitats.

Water temperatures may be cold enough to keep the shell epidemic out of Maine. But biologists are studying another problem: a stark drop in the number of larvae, the "baby" crustaceans that eventually grow up to be the next generation of lobsters.

"We're seeing a definite decline in settlement rates," says Incze, whose research shows a consistent downward trend since the 1990s. "But we don't know how it will pan out in the fishery."

So far, the anticipated dropoff in adult lobsters has not come to pass. Why not? There are so many factors involved that no single theory -- or prediction -- can explain matters precisely.

"What matters most is that we're learning," says Incze.

Though this year's catch is still months from completion, nothing yet suggests that it will be anything but strong.

"We've been hearing doom-and-gloom forecasts for years," says the Lobster Institute's Bayer. "All the while, we've maintained a very high catch rate."

Still, there are reasons for anxiety. And a hungry nation may soon wonder where its next claw is coming from.

The Good Life is a weekly column that chronicles products, people and trends in luxury consumer goods, travel, and fine food and drink. Write to: goodlife@money.com.