326 REPORT OF THE SECRETARY OF THE INTERIOR 
determine the maximum size and age obtainable by oysters in these 
waters and the percentage of mortality to be expected according to 
age and environmental conditions. 
Operation of an experimental oyster farm in South Carolina is 
providing considerable information on the relative value of the vari- 
ous types of bottom for seed-oyster production. On the Gulf coast, 
where oyster production has been at a low level for a number of years, 
the staff is cooperating with oystermen and with State conservation 
departments in formulating programs for the development and main- 
tenance of natural oyster grounds and for the creation of new grounds 
by planting shells and seed oysters. 
Methods of controlling starfish were tested under a variety of field 
and laboratory conditions by the staff and are being put into practice 
by many New England and Long Island oyster growers in a vigorous 
effort to diminish the losses caused by this abundant animal. Oyster 
drills, which are a serious menace to oysters in the Middle Atlantic 
States and are now becoming more numerous in Long Island Sound, 
have been found capable, when only 1 month old, of destroying ap- 
proximately five oyster spat a day. Because of the heavy depreda- 
tions of the boring clam, another oyster enemy found in Gulf coast 
waters, an investigation of the life history of this little-known mol- 
lusk has been undertaken at the Pensacola (Fla.) Station. 
The study of the effects of pulp-mill pollution on the oysters of 
the York River, Va., has been completed and a final report on this 
investigation will be made early in the fiscal year 1941. 
Sponge investigations —During the summer of 1939 samples of 
diseased sponges were received from Florida and subjected to micro- 
scopical examination. All were found to be infected with the fungus 
organism that had been discovered and tentatively identified during 
the preceding year by one of the Bureau’s biologists in surveys of the 
Bahama Island waters and the Florida Keys. From Key West, 
where the disease first manifested itself in the United States, it spread 
to Tarpon Springs, and by the end of December mortality of com- 
mercial sponges had proceeded to such a point that fishing was dis- 

continued on bars situated below eight fathoms. At the end of the | 
calendar year 1939 the number of sponges brought to the Tarpon 
Springs Sponge Exchange had noticeably diminished, causing con- 
siderable concern for the future of this resource. During the spring 
of 1940 there was evidence that the disease had abated and that a large 
crop of small sponges was in evidence. However, two or three years 
may be required for a substantial restoration of the commercial-sized 
supply. 
Aquicultural investigations —Studies concerned with the manage- 
ment of fresh-water sport fisheries are conducted along three prin- 
