BY NOW, the waters around Martha's Vineyard have given up their summer holiday blue for the gray-green appropriate to brooding skies and cold winds. It's scalloping time.

At dawn, morning after morning, the boats appear, just offshore from Vineyard Haven and Edgartown. Most of them are the length of a pennant or star class racing sailboat, but that is all they have in common with the frivolous white-wings of July. These are high-sided, broad-beamed working boats.

Each has an outboard motor and a high metal frame amidships. Each carries one to four people, all of whom are conspicuously busy, whether or not the boat is moving.

They are the commercial scallopers--the people who make it possible for many of Washington's home cooks and chefs to serve coquilles st. jacques and seviche. The scallops they are after are the bay variety: the small, sweet kind found in shallow water. The bigger sea scallop, which must be pursued at far greater depths a hundred miles or so out to sea, calls for heavier equipment, larger boats, longer expeditions and more workers.

Sea scalloping is a year-round activity, carried on without government restrictions on the catch. Bay scalloping, on the other hand, is seasonal, small-scale and closely regulated.

Bay scalloping begins at the end of October and goes on to the end of March, with minor variations decreed by local ordinance. Every commercial scalloper must start the season by taking out a $100 license. There are wardens watching every day to make sure nobody exceeds the four-bushel maximum allowed each person per day or violates any of the other rules of the game.

The scalloper is required to sort the catch so that it contains only mature scallops, which are identified by a growth ring--a ridge a third of the way in from the scalloped edge of the shell. (Yes, that's where the name of the creature originates.) Anything without that identifying mark is called a seed scallop and should be thrown back to go on developing for next year's harvest.

The sorting takes place on a rimmed culling board about two feet deep that spans the middle of the boat. Here, the contents of the drag--the metal and rope mesh receptacle the boat pulls along the sea floor to gather the scallops--are dumped after a winch has pulled it out of the water and over the side.

It's a mixed bag, every time. Seaweed of many kinds, stones, the odd mussel or clam, once in a while a flounder or a small lobster. And, of course, the scallops, which could justify their existence on the looks of their shells even if their innards weren't so good to eat.

There are also reminders that human beings are not the only predators a scallop has to look out for. There are always a few starfish in the drag, some clearly at work on the remains of a hapless scallop.

The starfish, which doesn't have those five strong arms for nothing, makes short work of any scallop it catches, prying the two shells apart and devouring the soft body inside. Not that the starfish catches every scallop it goes after.

Unlike such stick-in-the-mud fellow mollusks as the clam and the oyster, the scallop is not given to burrowing in the sea floor it inhabits. It is capable of spirited locomotion, opening and closing its two shells to achieve a kind of jet propulsion that is alleged to have taken members of the species as far as 11 miles from their point of origin.

The starfish, which around the Vineyard may be as big as a foot across, remain sufficiently undaunted and dangerous to the scallop supply that their human competitors are willing to pay a $2 bounty to anybody who comes up with a bushel of them. If this worries environmentalists, it hasn't yet become a public issue.

To bring in the daily quota, the scallopers go out as soon as it is daylight. The good fishing spots vary from year to year and even day to day, so the cluster of scallop boats may be seen in different places at different times. Always, though, the boats are close to each other. A highly individualistic line of work, it also has its communal side.

David Ritter, a Vineyard-born waterman who has been scalloping, off and on since he was in high school, says there is a notable comraderie among scallopers. They all know each other, meeting the same people out on the water year after year. While there is rivalry to see who can get the quota first each day and achieve other such distinctions, there's also a willingness to help if anybody gets in trouble.

There is, it seems, very little of the cutthroat competition that is sometimes found among fishing people. Nothing like what goes on in the oyster wars between Maryland and Virginia watermen or in lobstering circles.

Only a hardy few, such as David Ritter, go out in January and February when there are not many scallops to reward effort in the cold. More scallopers settle for the comparatively easy money to be had early in the season -- the gravy time, as they call it.

For the first two or three weeks, a hard worker can make $1,000 a week if the price to the scalloper is at a peak $5 a pound. In recent years, though, the price has been more often $3 to $4 a pound for the person out on the boat. It's the dealer in Boston, buying the shucked scallops to sell in Boston, New York and points south, who gets most of the difference between that and the $5 to $7 a pound the retail customer pays at the fish market.

Besides the price of scallops, the retail consumer has been concerned in recent years about missing out on the pleasures of scallop coral. Anybody who has eaten scallops in Europe knows there's more to the creatures than the white muscle, which is all Americans eat in the name of scallops.

Scallop shuckers in this country throw away everything but the muscle. When pressed, they will admit they've heard that the Indians used to eat everything in the scallop shell, the way everybody does with clams, oysters and mussels. Not many people get the chance now.

European tourism may yet apply the pressure necessary to bring the whole scallop to American markets, with or without shell. As of now, though, scallops are not sold here in the shell as they are in France, for example, and the scallopers have insufficient inducement to change their habits.

Shucking scallops is not the world's easiest job. The knife is always a menace, and the sharp shell edges are hard on hands. So is the water, even for those who wear gloves. Still, prying open a scallop doesn't take the skill or strength required to separate an oyster or a clam from its calcareous hideaway.

This is one of the reasons family scalloping is popular in places such as the Vineyard. While only 60 commercial licenses were issued this season in Vineyard Haven, for example, there were 1,000 family licenses authorized.

A family license doesn't cost as much--only $7.50 for the season. Neither does it entitle the holder to as many scallops. Whereas the commercial license holders are entitled to four bushels a day, family license holders get only one bushel a week.

It's a quite different procedure, too. Instead of taking off in a boat with its $100 drags and other equipment that adds up to as much as $8,000, the family scalloper is likely to prospect in nothing more substantial than chest waders, standing in water anywhere from a foot deep to waist high and scooping up the scallops with a clam rake and minnow net.

The family scalloper often stores the catch in a basket floating within easy reach, thanks to an inner tube. Since scallops freeze well, this sort of fishing provides a year-round supplement to the family table for many people who have other occupations to take up most of their working time.

Even for the commercial scallopers, though, the economic motive is not paramount. David Ritter, who has been, at other times in his life, a teacher and a professional golfer, likes it for its unpredictability. "It's a craps game," he says. "Every year is different, every day is different."

The scientists have tried to explain what makes a good scallop year and what motivates the movements of the being inside the shell that mythology calls the birthplace of Venus. However, their analyses of rainfall and water salinity and other such factors never seem to turn scalloping into an enterprise where results can be guaranteed. To the kind of free spirits scalloping attracts, that's worth as much as what the Boston auctions decide the price will be.

Ritter insists bay scallops taste best simply saute'ed in butter and eaten with a tart applesauce. But these dishes are good, too.

SCALLOP SEVICHE (4 servings) 1 pound bay scallops Juice of 1 lemon Juice of 1 lime 1 clove garlic, crushed 1 teaspoon grated lemon rind 1 tablespoon minced parsley or coriander leaves

Combine all ingredients, making sure all scallop surfaces have been exposed to the liquid. Cover, refrigerate and let stand overnight. Serve cold as a first course.

SPINACH-SCALLOP SOUP (4 to 6 servings) 1 pound fresh spinach 1 clove garlic 1 bay leaf 2 cups water 1/4 cup dry white wine 1 pound bay scallops 1/4 cup cream Salt and pepper, to taste

Wash spinach carefully. Simmer 5 minutes in salted water with garlic and bay leaf. Remove bay leaf. Pure'e in blender or food processor. Add wine, scallops, cream, and salt and pepper to taste, stir well and simmer 5 minutes.

MEDITERRANEAN SCALLOPS (4 servings) 1 cup cubed eggplant, unpeeled 1 clove garlic 2 leeks, well-washed and thinly sliced 1/4 cup olive oil 1 pound bay scallops 1/4 cup stoned black olives, preferably the Mediterranean variety 1/2 teaspoon grated orange peel Salt and pepper to taste

Saute eggplant, garlic and leeks in olive oil until eggplant is tender. Add scallops and continue cooking 5 minutes. Add olives and orange peel and taste for saltiness. Season with salt and pepper. Serve with rice.