2 U. S. BUREAU OF FISHERIES. 



oyster culture in the United States consists of (1) acquiring suitable 

 submerged bottom, (2) cleaning and preparing that bottom for the 

 growth of oysters, (3) sowing thereon shells or other mftterial 

 (cultch) for the attachment and growth of the young oysters, (4) 

 insuring the production of larval oysters by the proximity of natural 

 or planted beds of adult oysters, (5) protecting the oyster beds from 

 enemies, (6) transplanting as occasion requires to prevent over- 

 crowding and to facilitate growth and fattening, and (7) culling 

 and sorting for market.^ 



To conduct oyster cultivation along such liiies a considerable in- 

 vestment of capital is necessaiy, and the yearly program involves a 

 heavy expense in preparing to catch a " set " of the young oysters. 

 In the event of a failure to obtain a good " set," which unfortunately 

 has been the common occurrence of late years, the expenditure that 

 has been made is a total loss, and is further increased if the cultch 

 is taken up and dried out for use the following year. 



Consequently the aim of oyster growers and biologists interested 

 in this work is to place oyster culture on such a basis that a harvest 

 may be expected each year from the capital expended in planting and 

 cultivating the beds. 



In view of existing conditions, experiments were undertaken at 

 Milford, Conn., during the summer of 1923 to perfect a method of 

 artificial propagation by which oysters could be raised from the egg 

 in sufficiently large numbers to make the process one of practical 

 value, and to determine under controlled laboratory conditions the 

 most important factors necessaiy and favorable for growth. 



The author wishes to acknowledge his appreciation of the valuable 

 and cordial cooperation rendered by the Connecticut Oyster Farms 

 Co. in carrying on tliese investigations, and especially the help and 

 suggestions given by Capt. Charles E. Wheeler of that company rela- 

 tive to vaiious studies of the oyster situation and for generously sup- 

 plying oysters, laboratory facilities, men, and boats for this work. 



LIFE HISTORY OF THE OYSTER. 



The common oyster {Ostrea elangata Solander) of the Atlantic 

 and Gulf coasts of the United States is bisexual ; that is to say, each 

 individual possesses only one kind of reproductive organs, either 

 male or female, which do not change during the life of the indi- 

 vidual. 



During the summer millions of eggs are discharged by the female 

 oyster, which, after fertilization by the elements from the male, 

 develop after a day or two into free-swimming larvae. These float 

 and swim about with the tides and currents for a period of two or 

 three weeks, depending upon the existing conditions, such as tem- 

 perature, density, food, and tides. At the end of this free-swimming 

 period they attach themselves, if possible, to such suitable objects as 

 shells, rocks, brush, etc., which offer a clean hard surface to which 

 they may adhere (see figs. 7, 8, and 9). Though ten to sixty million 

 eggs are produced by a single full-grown oyster, only a few survive 

 and gi'ow to a size suitable for market. After the young oyster has 

 attached itself, or " set," it is incapable of changing its position, 



' " Oysters : Tlie world's most valuable water crop." By Hugh M. Smith. National 

 Geographic Magazine for March, 1923. Washington. 



