104 REPORT OF THE SECRETARY OF COMMERCE 



of the Bureau augmented by 20 temporary investigators and 50 

 assistants whose period of employment varied from 3 to 9 months. 

 Excellent cooperation was received from the various States, the 

 Works Progress Administration, and the Transient Rehabilitation 

 Camps which supplied about 110 relief laborers for the field 

 investigations. 



The oyster pest investigation was directed toward the control of 

 three major organisms destructive of oysters: (1) the starfish in- 

 festing the waters of New England and the North Atlantic States; 

 (2) the drill in the Delaware and lower Chesapeake Bays and extend- 

 ing as far south as Texas; and (3) the so-called "leech", the recent 

 outbreak of which has destroyed extensive areas of oyster-producing 

 bottoms in Florida. The problems of the destruction of oysters 

 caused by the boring sponge and the conch, although of lesser im- 

 portance, were also included in the jDroject. Practical methods that 

 can be used by the oyster industry for the control of these pests must 

 be based on a thorough knowledge of their life histories and an 

 understanding of their habits and activities. 



Oyster pest investigations were also undertaken in the inshore 

 waters of Florida, Alabama, and Texas. Previous surveys showed 

 that the most destructive pests of this section are the borer and the 

 "leech" or flat worm. Other pests associated with these, but whose 

 relations as commensals or enemies are undetermined, are the boring 

 sponge, boring clam, barnacles, and mussels. 



During the summer of 1935 the oyster bottoms of the Texas coast 

 were surveyed to discover the kinds and numbers of oyster pests 

 present and to devise methods of control. Approximately 800 miles 

 of coast line were examined between Corpus Christi Bay and Galves- 

 ton Bay, examinations being made of commercial reefs to determine 

 the condition of oysters, salinity, temperature, character of the bot- 

 tom, and abundance of oyster pests. The most common organism 

 infesting oysters is the boring clam. The borer, the common conch, 

 and the boring sponge are also present in moderate numbers. In 

 addition to pests, however, it was found that the greatest danger to 

 oyster beds in this section is from occasional floods from the rivers 

 of the coastal plain. Recommendations were offered to assist oyster 

 growers in meeting these conditions and in managing their holdings. 



Because of the increased activity in connection with the oyster 

 pest control investigations, the regular studies for improving and 

 promoting oyster culture were greatly curtailed. A study of the sea- 

 sonal changes in the mineral content of oyster meats and its relations 

 to environmental changes was conducted and completed during the 

 year. In Long Island Sound variations in the quantities of copper, 

 iron, zinc, and manganese of great nutritional and therapeutic value 

 in the human diet were traced to aid in the producing and marketing 

 of oysters of standard quality. Technical direction was also afforded 

 to State officers in Alabama and the Works Progress Administration 

 in their project of developing oyster-producing grounds. 



On the Pacific coast a 5-year study of problems concerned in the 

 cultivation of Olympia oj^sters in Puget Sound was brought to a con- 

 clusion. The purpose of this investigation was to determine factors 

 influencing the spawning and setting of Olympia oysters in order to 

 develop a system whereby oyster growers can be assured annually of 

 an abundant supply of seed. Spawning habits, life and attachment 



