BUREAU OF FISHERIES 103 
of the Pisgah Division of the Pisgah National Forest, N. C., as an 
experimental project to demonstrate the value of scientific stream 
management in improving angling conditions. 
Laboratory studies on trout culture included: (1) Feeding experi- 
ments at the Leetown hatchery to determine efficiency of certain low- 
cost diets; (2) breeding experiments at the Pittsford hatchery in 
which it appears that a strain of trout more resistant to disease is 
being developed; and (3) experiments to determine the cause of the 
heavy losses of brook trout eggs suffered at the Leetown hatchery. 
The California trout investigations have proceded along two major 
lines of effort: Experiments at the Hot Creek Station to deveiop 
a superior brood stock, and coastal stream studies of the steelhead 
trout. Detailed plans have been drawn up for the development of a 
major stream and lake management project on the Convict Creek 
drainage in eastern California. Investigations dealing with the life 
histories and migrations of the steelhead and salmon of the coastal 
streams have been continued in the Klamath River and in Scott and 
Wadell Creeks. 
Investigations in pond culture for bass and other warm-water 
fishes were conducted at Marion, Ala., during the year. The results 
confirmed those of previous years, showing that production of food 
organisms is greater in ponds containing vegetation than in those 
without an appreciable growth of higher plants. Comparative 
studies of the suitability of two streams, one in West Virginia and 
the other in Virginia, for the production of bass, showed marked 
differences in the rate of growth of both bass and forage fish. 
Facilities for the study of fish diseases were markedly improved 
during the year by space provided in the new hatchery at Quilcene, 
Wash., where various methods for the prevention and cure of dis- 
eases will be tried under experimentally controlled conditions. As 
im previous years, epidemics reported from hatcheries were investi- 
ae and hatcherymen were advised on disease problems. The 
isease service has proved very popular and a large number of 
specimens submitted by various State and Bureau hatcheries and 
by private individuals were examined at both the Washington, D. C., 
and Seattle laboratories. 
SHELLFISH INVESTIGATIONS 
Shellfish investigations during the fiscal year 1937 comprised 
studies of the metabolism and fattening of the oyster; determination 
of the factors involved in sex changes in oysters and clams; inves- 
tigations in the biology and control of various natural enemies of the 
oyster: and observations on the effect of pulp mill pollution on 
shellfish. 
The production of oysters of high nutritive value is at present the 
principal problem of oyster culture in the Northern States. Good 
oysters are characterized by the storage of a large amount of gly- 
cogen in their tissues anc by the presence of lesser quantities of 
metals important in human nutrition, especially iron and copper. 
Observations on the seasonal fluctuations in the chemical composi- 
tion of ovsters kept under known natural conditions have now been 
completed and form an important contribution to studies upon 
