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Winter 1997

Research Magazine > ARCHIVE > Summer 95 > Article

A Rising Tide for Georgia Clams
by David Hart

Call 'em quahogs, littlenecks, cherrystones or chowders. But whatever you call them, these shellfish have a future in Georgia, if Randal Walker can do anything about it.

Hard clams, yet another name for the same critters, are the leading commercial clam variety in the United States. Walker's clam research has shown that, while clams may never topple shrimp as the state's top seafood money-maker, quahogs may be an ideal "crop" for Georgia's coastal waters and an extra boost for the coastal economy.

Clams have never been a big catch in Georgia, although they have been harvested sporadically since the 1880s. But Walker found that native clams can be harvested profitably, at least by small numbers of fisherman, despite a 1960s study that claimed the state's clam population couldn't support commercial clamming.

"The problem with that [survey] was they looked where the clams should have been. They didn't look where [the clams] were," said Walker, an assistant research scientist with the UGA Marine Extension Service on Skidaway Island.

Unlike hard clams in the Northeast, which live below the low tide mark, Georgia quahogs live between the high and low tide marks; they also inhabit small salt-water creeks instead of the main rivers and sounds. Georgia clams have other ecological quirks, too. For example, they grow all year instead of hibernating in the winter. And up to 200 of them can live in a square meter -- more than 12 times the density in commercial clam beds in the Northeast.

"We found that the basic ecology of the hard clam in Georgia is totally different than it is either to the north of us or to the south of us," Walker said.

However, breathing life into the Georgia clam fishery involves more than pointing out where the clams are hiding. Walker, in research funded by the Georgia Sea Grant College Program, also looked into the clams' reproductive biology and growth rate. He and his team found that the clams spawn twice, sometimes three times, each year and that the clams grow to market size in only two years -- less than half the time of their Northern counterparts -- because of Georgia's mild winters.

Despite this good news, clams haven't made a big splash in Georgia's seafood industry, which provides about 4,500 jobs along the coast, for two reasons. Initially, Walker intended clams to be a winter market for the state's shrimpers -- some extra cash in the off-season. However, shrimpers can't take their 60-foot boats up the small creeks the clams call home. Blue crab fishermen, on the other hand, have the same off-season -- and much smaller boats.

Still, clams didn't catch on with either group, because of the second reason, which has less to do with desire than with geography.

"Although we have high population densities, the overall area that contains clams is very small," Walker said. "So it would be very easy for commercial fisheries to go in there and overharvest everything."

In 1989, Georgia's clam-harvesting area was reduced even further when the Department of Natural Resources closed two of the most productive areas because of questions about the leases. Today, the state's clam fishery only rakes in about $40,000 a year, down from a 1988 peak of more than a quarter million dollars.

Hunting the wild Georgia clam, then, has its limits. But it's not the end of the story. Because Georgia quahogs grow to market size so quickly, they are ideal for aquaculture. And because Georgia sea islands have a quarter of the remaining salt marshes in the United States, many of which are protected as natural preserves, clam farmers are guaranteed plenty of pristine "farmland."

But raising clams isn't as easy as chucking baby clams into the mud and waiting. In addition to the research on ecology and growth rates, Marine Extension Service researchers had to explore questions about the clam's predators, feeding habits and diseases.

Humans aren't the only ones who munch on the low-calorie clam. Whelks, moon snails, oyster drills, water birds, skates, rays and even some fish such as drums dip into the clam supply for their diets. But in Georgia, "blue crabs are our worst enemy," Walker said. "You get a blue crab in there and he eats everything."

Researchers including Peter Heffernan, an associate marine scientist with the Marine Extension Service, and John Crenshaw, a Georgia Tech biologist, also conducted experiments using genetic selection to produce faster- growing clams. After only a few clam generations, this work has produced clams that grow up to 9 percent faster. Heffernan's research into potential diseases showed that clams are naturally disease-resistant and, in fact, are immune to diseases that plague other shellfish.

But Walker and his team still needed to find a way to plant and harvest the clams, so they developed a clever, low-tech operation. On firm creek bottoms, they use gravel-filled, mesh-topped wood boxes set upon cinderblocks. They would have preferred using inexpensive sand instead of gravel, but the 10-foot tides tend to wash the sand away "and the whole box just floats down the river," Walker said. For soft, mud bottoms, mesh bags work better.

The more difficult step is producing the "seed" clams, and this led to another whole set of research questions. What do clams like to eat? How do you conduct a clam taste test? What sort of ambience do clams prefer for their all-you-can-siphon buffet?

Commercial hatcheries along the East Coast regularly grow seedlings to 3 or 4 millimeters. However, Georgia clam farmers needed a cost-effective way to grow them to 8 or 10 millimeters -- again, so the tides don't wash them away. Walker began his research using artificial light in the lab to grow and test various algal feeds for the clams. He found that clams aren't finicky and will eat the same algae year-round, but they grow better with a variety of algae in their diet.

But a practical desire for low costs turned him away from the expensive, temperature-controlled rooms with banks of lights that many seed-clam producers use. Instead, Walker and his crew designed a greenhouse, which uses old-fashioned sunlight to grow algae and the young clams.

"Our building is designed to grow the seed to that [larger] size, and then we move that seed out to the river," Walker said. "At this point, you just can't beat Mother Nature. Nobody can."

Clam farming can be profitable and may one day catch on; Walker just has to convince Georgia shrimpers and crabbers to invest in equipment and, for the shrimpers, smaller boats. At the moment, however, shrimp prices are up, so it's hard for Walker to make his point.

"Georgia is a very traditional fishery-oriented society," Walker said. "Shrimp is king.

Clams may not be kings, but with a little luck, some hard work and a growing demand for pasta with clam sauce, Walker's research may catapult Georgia clams into a league of their own.


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