yw) U. S. BUREAU OF FISHERIES 
INTRODUCTION 
The mastery and utilization of the forces of nature depend first of 
all upon an understanding of natural laws. With such a knowledge 
these forces can be harnessed, controlled, and directed to economic 
advantage in some cases or, if they are uncontrollable, human activities 
can be ordered in accordance therewith. The scientific studies of the 
Bureau of Fisheries provide a body of facts of permanent value re- 
garding the natural history of fishes upon which commercial and 
sport fishing depends. Such contributions to our knowledge are 
therefore permanent contributions to social progress even though 
opportunities for practical application may not have been realized 
completely as yet by business enterprise, nor in Governmental 
organization. 
The following illustrations show ways in which these facts are 
being turned to practical advantage in fishery management. The an- 
nual runs of salmon on the Pacific coast and in Alaska are managed 
by regulating commercial fishing in such a way that ample natural 
reproduction is assured to sustain the supply and at the same time to 
provide ever increasing quantities of nutritious food. 
Knowledge of the variations in natural reproduction, growth, move- 
ments. and local concentrations of the haddock, mackerel, squeteague, 
and other fishes on the Atlantic and Gulf coasts permits prediction of 
annual yields of some species to promote orderly and efficient market- 
ing of the catch, directs the way to better utilization of the fish supply 
through avoiding the waste of immature and unmarketable fish, and 
demonstrates the necessity of protecting the breeding and nursery 
erounds of migratory coastal fishes by unified State action throughout 
the range of the fishery. 
A knowledge of the reproduction, growth, and natural requirements 
of the oyster recently obtained has laid the foundation for a great 
expansion of oyster farming in our coastal waters that may be relied 
upon to restore production of this valuable food product to its former 
high levels when economic conditions permit. 
In interior waters, studies of stream pollution have made perma- 
nent contribution to the restoration of recreational resources. 
Through this work an understanding of the effects of domestic sewage, 
industrial wastes, and other pollutants on aquatic life has been ac- 
quired. Future efforts toward the purification of streams and the, 
restoration of angling waters may therefore proceed along intelligently 
directed lines. 
As an outgrowth of these studies there has been developing a definite 
trend in public thought toward international and interstate coopera- 
tion in the conservation of fishery resources. 
In the interest of properly administering an extensive program 
of scientific investigations concerning the fundamental problems of 
conservation, and application of the knowledge acquired to the prob- 
lems of practical fishery management, the Division of Scientific In- 
quiry is organized into eight separate sections each with a responsible 
experienced fishery biologist in charge who reports direct to the Wash- 
ington office. Such organization provides a desirable degree of 
decentralization of administrative control and permits direct attack 
upon the problems of major importance In each district. 

