Oysters, the United States Deputy Commissioner of Fisheries tells us, are not only the most extensively eaten of all shellfish, but are also, with a single exception, the most valuable economically of all aquatic animals. The United States furnishes eighty-eight per cent of the total quantity of oysters produced, and has at least 150,000 men and women engaged in the industry. While all of the coast states but one deal in oysters, in fifteen of them this is the chief fishery product. However, the greatest number of oysters in this country come from Long Island Sound, Maryland, Virginia, Mississippi, Louisiana, Texas, and Washington. France produces the crop next largest to the United States. Japan and China are also oyster producing countries.

It is easy to see what a demand there must be for oysters. This is no doubt partly due to the fact that they are easily digested, but it is probably also because they can be used to furnish considerable variety to the diet, since they lend themselves to so many ways of preparation. They are almost universally used, appearing on the menus of the most exclusive as well as the cheapest restaurants.

Langworthy gives the following composition for oysters:

Water...........

Nitrogenous substances.....

Fat............

Carbohydrates........

Salts............

88.3 per cent 6.1 per cent 1.4 per cent 3.3 per cent 1.9 per cent

The total solids are about equal in amount to those of milk, but a quart of shucked oysters costs from four to five times as much as a quart of milk. Oysters, like milk, are bulky for the amount of nourishment which they contain. The nitrogen present is probably not all in the form of protein; the carbohydrate is largely the glycogen stored in the liver of the animal. Milk and oysters are the two animal foods which are exceptional in furnishing large amounts of carbohydrate, although not in the same form. Eaten raw, oysters are an unusually digestible food; even cooked, they are still easily digested, although they are less so when fried than when cooked in any other way.

Long ago the demand for oysters outran the natural supply and oyster culture became an industry. Italy began their cultivation about a hundred years before the Christian era, and within the last century even those places where oysters were naturally most abundant have been forced to cultivate them. In order to understand what oyster farming means one must know something of the habits of the oyster. An oyster produces an incredible number of eggs, apparently to compensate for the fact that in natural life the percentage of those that will find suitable conditions for development is very small. Oyster farming consists in the preservation of as many of these eggs as possible. The newly-born young is not more than one one-hundred-and-fiftieth of an inch long, nearly transparent, has no shell, and swims freely. By the time it is large enough to be visible to the naked eye it can no longer move around. To survive, during the swimming period it must not only escape being eaten by adult oysters, fish, and other shellfish, but it must find a suitable place in which to develop. If it sinks on a muddy, soft sandy, or slimy bottom it cannot live. If, however, it attaches itself to clean shells it has a chance to survive. But the oyster has many enemies against which even the hard shell that surrounds it does not afford perfect protection. Certain mollusks drill minute holes through the shell and so get at the oyster's body, starfish may force the shell open and devour the contents, or it may be attacked by certain kinds of fish with jaws powerful enough to crush the shells; or barnacles, sponges, or mussels may grow so thickly on the shells as to cut off food and oxygen. Oyster culture consists mainly in providing suitable beds of shells for the young oysters and in protecting them from as many of their enemies as possible. Palisades are sometimes erected around the beds to keep off the large fish.

When ready for market, the oysters are dredged, freed from dirt and attached shells, and sorted according to size. Three sizes are usually recognized. The smallest, called "half shells", are usually eaten raw, the middle-sized, sometimes called "culls", are for general use, while the largest or "box" oysters are selected for frying. The difference in size is mainly a question of age, for, while there are many varieties of oysters, there is not much variation in size between the varieties. One peculiarity of the oyster is that it remains just as tender when old as it was when young. The fact that it takes no exercise may explain this. The names Blue Point, Rockaway, and the like, which used to indicate the locality from which the oyster came, now usually mean no more than size. For example, many small oysters are called Blue Points.

Oysters stand shipping well. If left in the shell, kept cool, and sprinkled occasionally with brackish water, they will live for weeks without any deterioration. Even when "shucked", if kept cool, they remain edible for eight to ten days, but they keep best if removed from the oyster liquor. Shucked oysters are usually washed carefully in a number of waters, and packed in air-tight receptacles surrounded by ice. Care must be taken not to let them become frozen. Formerly, they were shipped floated in a tub with a cake of ice. The objections to this practice were twofold. The ice often had to be replaced during the shipping, with the consequent danger of infection. Secondly, oysters lose salts and much flavor if soaked in fresh water, although they gain in size from the absorption of water. Consequently many states require the other method of shipment and specify that the oysters sold shall not contain more than ninety per cent water. Because they take up fresh water, oysters are sometimes "fattened" by placing them in the fresh water at the mouth of rivers. It is most necessary that such beds shall not be in water contaminated by sewage, lest the raw oyster become a carrier of typhoid germs, but, even at best, there seems to be no reason for allowing the practice.

The notion that oysters cannot be eaten during the months which contain no "r" in their names, May, June, July, and August, has no real foundation except that they are more liable to be contaminated by the bacteria in the water when it is warm. Oysters are not good when they are spawning, but this requires only from three to four weeks and takes place in different species at different seasons. Of course, if not properly kept cool, oysters spoil more quickly in hot than in cold weather.

Oysters occasionally appear unusually green. This is sometimes due merely to certain seaweeds or diatoms on which they have been feeding, and does not in any way impair the oyster as an edible product. Only rarely is it due to copper, and probably never in amounts sufficient to prove injurious.

References

U. S. Dept. of Agriculture. Farmers' Bulletin No. 85. "Fish as

Food." National Geographical Magazine, Vol. 24 (1913), pp. 257-281.

Smith. "Oysters; the World's Most Valuable Water Crop."

Questions

1. Compare the cost of oyster stew and a cream vegetable soup.

2. Compare the cost and taste of fish chowder made at home with a canned chowder of good brand.

3. Should the crabs frequently found in oysters be used ?

4. Are oysters which are greenish good to eat?

5. In what months are oysters not used, and why?

6. If fresh lobsters and clams are obtainable in your market, compare the cost of these with oysters. If not, compare the cost of canned lobsters and clams.

7. Are shellfish expensive forms of nutriment?