68 U. S. BUREAU OF FISHERIES 
eries for Bureau use in experimental oyster farming, but present 
facilities are sufficient for operating only one. 
During this first year emphasis has been placed on seed produc- 
tion. As a means of standardizing results, cultch material consisted 
exclusively of 60,000 bushels of clean oyster shells, made available from 
a local cannery, which were planted for catching spat and hardening 
the bottom. 
Toward the end of the year 5 mud and shell dams were constructed 
to impound an area of about 25 acres of marsh, 5 acres of which are 
being utilized for growth studies of seed oysters. One thousand 
bushels of seed from the 1939 stock have been transplanted to this 
location. 
Briefly summarized, the first year’s work has provided data on 
the following subjects: (1) Daily hydrographic observations were 
made of the ‘bottom water temperature, salinity, pH, and turbidity. 
(2) Although the water temperature reached 20.0° C. by the end of 
March, the “oyster- setting season was observed to extend from the 
end of May to the first of November. Shell-bag collectors were 
found to be unsuitable for local waters due to the very slow rate of 
spat attachment. (3) The rate of growth of spat was determined 
during their first 6 months by measuring samples twice a month. 
A few early spat had reached 3 in. in length at the end of 6 months. 
(4) The relative value of various types of bottom for collecting seed 
was shown by actual production. <A total of about 4,000 bushels of 
seed oysters was produced on the experimental area in Horse Pen 
Creek this year. (5) The existing belief that setting of oysters in 
South Caroline waters occurs only” between tide lines was disproved. 
Oyster larvae readily set below low-water mark if clean cultch is 
provided. However, less than 10 percent of spat survive as long as 
6 weeks at such depths. 
Gulf of Mexico—Oyster production on the Gulf coast has been at 
a low level for a number of years, and markets have found it neces- 
sary or advantageous to import oysters from the Middle Atlantic 
coast to satisfy the demand. ' Almost all of the oysters harvested on 
the Gulf coast, with the exception of those produced on private 
grounds, chiefly in Louisiana, are taken from natural oyster bars, 
or reefs, which have been built up by the slow accretion of centuries. 
Otherwise, little private oyster culture is practiced, although the 
various States attempt to maintain the natural oyster bars by 
extensive planting of cultch and seed. 
The following “difficulties are faced by State organizations in their 
attempts to maintain a large, dependable production of oysters: 
(1) More oysters are harvested than the grounds should produce, 
with the result that the size as well as the quantity harvested has 
been reduced. (2) There frequently is considerable mortality due 
to freshets, or periods of very low salinity in oyster- producing bays, 
caused by heavy rains or melting snow inland. (3) Some mortality 
caused by oe or parasites, such as conchs, sporozoans, and 
other organisms. (4) The effect of such nonparasitic organisms as 
the boring clam (Martesia), which inhabits the shells of oysters, is 
not yet known but will be determined. 
In order to solve some of the most serious problems of the oyster 
industry on the Gulf coast, the Bureau of Fisheries established a 
permanent laboratory near Pensacola, Fla., in 1937. For this pur- 
