520 U. S. BUREAU OF FISHERIES 
the feeding and reproduction of oysters have contributed to our 
knowledge and made possible the more complete utilization of the 
present supply and a material increase in reproduction in unfavor- 
able areas or seasons. Thus, through these studies of physiology, the 
fact of hibernation at a temperature below 41° F. has been re- 
affirmed; at which time, as feeding is discontinued, it may be 
possible to market, without danger to the public health, oysters 
from areas that, during warm weather, may be condemned be- 
cause of slight pollution. Likewise, through studies of the physi- 
ology of reproduction, it has been possible to induce spawning under 
experimental conditions. The possibility, therefore, is by no means 
remote that spawning on the natural beds likewise may be induced 
artificially during seasons when natural spawning would not occur 
otherwise, thus materially increasing the supply of oysters by insur- 
ing an abundant supply of seed. In addition, studies on the ecology 
and behavior of oyster larvee have resulted in the designing of highly 
efficient spat collectors, making it possible, at small cost, to harvest 
a profitable crop of seed oysters on bottoms where setting does not 
occur naturally. 
Congress has vested the control of the Alaskan fisheries in the 
Department of Commerce, and the regulations promulgated by the 
Secretary are administered by the Commissioner of Fisheries. Per- 
haps in no other locality has it been realized so keenly that fishery 
regulations must rest upon a solid foundation of biological knowl- 
edge; and it has been one of the most important functions of the 
division of scientific inquiry, with the extensive cooperation of the 
Alaska division, to conduct the biological researches which make pos- 
sible the scientific husbanding of the great salmon fisheries. The past 
year has marked the culmination of a long period of investigation 
of the biology of the Pacific salmon. As a result of these studies, 
an understanding of many of the factors that cause the fiuctuation 
in supply has been gained. To be able to predict the degree of 
abundance of any species of fish in future years is one goal of all 
fishery investigators, and it now appears that eventually reliable 
predictions concerning the magnitude of the runs of salmon in certain 
localities may be made a year or more in advance. The realization 
of these hopes will not only make possible the fullest control of the 
supply through regulation of the fishery, but will afford economic 
protection to the industry in years when poor runs are anticipated, 
which should result in the saving of millions of dollars. 
Gratifying results in the newly initiated work in aquiculture also 
have been obtained. The first year’s pond experiments at Fairport, 
in which the ponds were fertilized to increase plankton production 
and in which various plankton-feeding species of fish were used as 
forage for the game species, has resulted in a marked increase in 
total production. Results of equal promise have followed the bu- 
reau’s investigations in the treatment and control of diseases of 
hatchery-reared fish. Because of the greater demand in recent years 
for larger fingerlings for stocking streams and lakes, fish-culturists 
have attempted to rear their stocks to larger sizes. The effectiveness 
of the hundreds of hatcheries throughout the country has been les- 
ian pases on experiments initiated before, but completed after, the end of the calendar yeal 
