150 MARINE FISHERIES OF NORTH CAROLINA 



inert matter ingested. Oysters are capable of pumping as high as 34 liters of 

 water per hour while feeding for 94 per cent of a 24-hour period (Loosanoff 

 and Nomejko, 1946). Thus, the concentration of food organisms is of impor- 

 tance in feeding. 



Within the past decade the artificial enrichment of the waters through the 

 use of various chemicals to stimulate growth of minute organisms (collec- 

 tively known as plankton), has received a good deal of attention. Some 

 promising results have been obtained in fish ponds. Production of oysters 

 may possibly be increased through similar means. Studies of fattening 

 methods are of importance since criteria of value have changed. The weight 

 and volume of meat content are concerned in the evaluation of the product 

 rather than bulk measures of oysters in the shell. The proportion of meats to 

 the whole oysters may vary considerably. Poor oysters yield as low as three 

 or four pints of meats per bushel; good oysters may yield up to eight pints of 

 meats per bushel and in unusual cases yield as high as 12 pints per bushel. 

 The significance of increased yields per given unit is evident. 



SEX REVERSAL. The important phenomenon of sex change was first shown 

 in the European oyster by Orton (1921) and in our native eastern oyster by 

 Needier (1930), Burkenroad (1931), and Coe (1932). The studies have 

 shown a correlation to exist between size of the oyster and sex, and between 

 the age of the oyster and sex. Small oysters are predominantly males, Coe 

 has shown that in the first year of maturity the percentage of males varies 

 from 70 to 95 per cent. A differential rate of sex reversal appears with in- 

 crease in age, resulting in an approximate equality in sex ratio. One signifi- 

 cance of these studies to the industry may be in the cull laws that exist. Many 

 states require the return of small oysters to the beds in order to insure a 

 future supply of oysters. Such a procedure may possibly result in the removal 

 of a greater percentage of large oysters which proportionally produce more 

 sex products as well as the removal of a greater percentage of females. Thus 

 a natural balance may be upset in some localities. 



"coon" oysters. In the waters of North Carolina and throughout the 

 south there are found great masses of oysters growing in clusters on natural 

 reefs along the shores. From the typical elongated, narrow shape they are 

 commonly called "cat's tongue" or "coon" oysters. The name "coon" prob- 

 ably had its origin from the word raccoon, and is applied to these oysters sup- 

 posedly because raccoons frequently feed upon oysters that grow on reefs 

 exposed between tides. Grave (1904) says that the name is applied to the 

 oysters because they resemble, in shape, the paw of a raccoon. 



Although many believe that these oysters constitute a different variety, 

 there is no definite basis for the belief. The elongated shape, which is gen- 

 erally in a vertical position, is attributed to the crowded conditions under 

 which the oysters live or attempt to keep above the surface of the bottom. 



