INTRODUCTION 
Progress in biological inquiries during 1939 recounts numerous ad- 
vances and extensions of scientific knowledge of the Nation’s aquatic 
resources. From the research of the Division of Scientific Inquiry 
there is emerging a philosophy of fishery management that is finding 
direct application in State laws for the protection and development 
of the commercial fisheries and in the more active measures, adopted 
for the rehabilitation and maintenance of the recreational fisheries. 
The growth and expansion of fishery research throughout the al- 
most 70 years that have elapsed since the establishment of the old 
U. S. Fish Commission is an interesting study. The early scientific 
investigations were either casual surveys or attempts to discover and 
to catalogue the aquatic resources. The strictly scientific surveys 
of the Albatross, the Fish Hawk, and the Grampus that bridged the 
end of the last and the beginning of the present century were paral- 
leled by or followed by special investigations of specific phases of 
our inland water resources. From those studies there resulted a basic 
fund of oceanographic, ichthyological, and general zoological infor- 
mation. That basic research program has never ceased, for the spirit 
of discovery still persists throughout all of the Bureau’s scientific 
endeavors. 
The purely systematic and distributional studies of fishes and in- 
vertebrates of commercial importance did not long remain ends in 
themselves. It was not only necessary to know what we had but, 
also how each item behaved in relation to its environment. Thus life- 
history and ecological studies of the most important fishes, molluscs 
and crustaceans were conducted with the object of obtaining infor- 
mation that would, suggest means of insuring a continuation of the 
supply at a safe level of abundance. Statistical methods of analysis 
were adopted to interpret the large quantities of data that were ac- 
cumulated. Fundamental concepts of fishery management were de- 
veloped and applied and biological investigation thus become an 
indepensable tool of conservation. 
The specific aim of the research concerned with both marine and 
fresh-water fisheries is an analysis of the fluctuations in natural 
abundance and production in an attempt to discover methods of 
balancing commercial yields against ‘reproductive activities. In 
other words, the continuation of any fishery resource demands that 
an adequate breeding population always remain and that commercial 
production should remove only the surplus, or “annual crop.” 
Unfortunately, the depletion of many commercial fishery resources 
has been allowed to progress to a critical point before the financial 
support of investigation to discover means of protection was pro- 
vided. Any attempts at rehabilitation based on scientific findings, 
necessarily are slow, especially since the fishing industry must be 
maintained at as high a level of production as is consistent with the 
preservation and recovery of the stocks. The research programs 
1 
