On a quiet nook of a Chesapeake Bay creek, a group of Virginia high school students crowded onto a small dock to check the progress of the 2,000 oysters they've been raising for almost a year.

The half-dozen teenagers, also known as "oyster gardeners," are a small but vital element of a regional effort to replenish the bay's supply.

"How's the water clarity?" asked their marine biology teacher, Shawna Gilbert. She is overseeing the program and housing the oysters in the creek that washes up to her back yard.

"It's at the fourth mark," answered Jeramie Ashton, 18, as he pulled a painted sphere from the water. The sphere dangles from the end of a rope that is marked every four inches to show how far down the students can see it.

Ashton's classmates, who attend Washington and Lee High School in the tiny Northern Neck town of Montross, voiced their approval as they went about measuring the water's salinity level and checking for barnacles.

The students are supported in their efforts by scientists, environmental groups, politicians and hundreds of extremely hopeful watermen. They all seek to make the oyster population in the bay and its surrounding waters as large as it was in Colonial times, when giant oyster reefs were as common as bobbing crab pots are today.

Similar efforts also are underway in Maryland, New Jersey and New York as an increasing awareness of the oyster's plight and a greater understanding of its importance to its ecosystem have mobilized support.

In this battle to restore oysters, scientists have found their pearl. A report by the Chesapeake Research Consortium says three-dimensional reefs, rather than the flat-bottom beds that have been the preferred breeding grounds of oysters for more than a century, can provide the type of long-term housing that oysters need.

Oysters thrived in three-dimensional structures before watermen began harvesting them. The larger, more versatile reefs allow free-floating larvae to hook on to the shells and then protect them for three years, the time they need to grow to full size.

"Attaching oysters to each other assures that they'll have other oysters nearby to spawn with and reproduce over thousands of generations," said Robert Brumbaugh, fisheries specialist for the Chesapeake Bay Foundation.

Scientists are using charts from the 17th century to guide their construction of the reefs, and an assortment of groups, with high school students and baymen among them, are raising oysters that soon will serve as the foundation for a new generation of reefs.

Students have become an integral part of the project because they grow and monitor the oysters at virtually no cost. The return is a hands-on marine biology lesson.

After gauging the salinity and clarity of the water, Gilbert's class pulled the plastic sack of oysters from the creek and laid it on dry ground, where the students measured 50 of them and checked to see whether any had died.

A tiny crab popped out of the pile of oysters. Then another.

Before long, a couple dozen baby crabs were crawling through the grass, presumably trying to find their way back to the water. So the students split ranks, with half finishing the test and the other half rounding up the crabs to return them to their home.

The teenagers repeat these exercises, minus the crab rescue, once a month and forward their findings to scientists.

Oyster harvests reached their peak in the late 1950s, at millions of bushels a year. Virginia's harvest was down to 14,000 bushels last year, while Maryland pulled in 285,000 bushels.

But there is reason for hope. Observers predict that the harvest will perk back up this year, and they expect the turnaround to continue.

Still, the years of diminishing returns have pushed many away from a career on the water. Tiffany Brownley, an 18-year-old senior at Washington and Lee, works on the water during her summer vacations but sees a future in medicine instead of oystering.

"Once you're a waterman, you're always a waterman," said Brownley, who comes from a family of fishermen and wears a necklace with a gold crab dangling from it. "I'll always be out here in some kind of way, but there's not enough money in it for me."