+ U. S. BUREAU OF FISHERIES. 
INTRODUCTION. 
The fisheries industries are immediately confronted with such acute 
problems of distribution of products that it would seem only natural 
if attention were temporarily detracted from the underlying and 
enduring problems of the industry—those relating to maintenance of 
the resources upon which the industries are based. Nevertheless the 
discussions among representatives of all phases of the industry when 
eathered together in such meetings and conferences as have been held 
during the recent period of stress have always brought to the front 
the problems that have to do with the perpetuation of fishery re- 
sources. Such conditions as the depletion of shad, the decline of the 
blue-crab fishery, and the deterioration of inshore waters through 
pollution, command such earnest consideration on these occasions as 
to prove that fishermen and dealers of broad vision are not misled 
through immediate difficulties in one department of the industry to 
minimize the importance of permanent sources of supply. 
Upon due thought, of course, it is evident that the problems of 
supply must not be forgotten even momentarily; for the difficulties 
of distribution can be only heightened by continued depletion of re- 
sources and an inevitably accompanying increase in costs of produc- 
tion relative to the costs in competing industries. Obviously it can 
not become easier to market fish when they become less easily obtain- 
able relative to other materials of protein food. No economic fact 
ean be plainer than that diminishing abundance of fish must be 
followed by increasing prices and decreasing consumption. 
It is, then, a fundamental and enduring principle that the perpetua- 
tion of the fisheries and the maintenance of their relative rank among 
other food-producing industries are contingent upon the continued 
productiveness of the fisheries—in a word, upon conservation. Con- 
servation in turn depends upon the exercise of intelligence and re- 
straint in the exploitation of fisheries resources, upon sound action 
in removing unnecessary causes of depletion, and upon wisdom in 
adopting plans for bringing about where possible an increase of 
particular fish or shellfish. The decline of valuable fisheries has been 
witnessed too often to admit of continued faith in the inexhaustibility 
of fish or shellfish of any kind. Yet the intelligent determination of 
what restrictive measures are necessary, what means of exploitation 
are unreasonable, or what plans of propagation or development are 
profitable can be made only upon the foundation of full and correct 
Imowlec lge of the life histories, habits, and conditions of life of the 
fish that are to be considered. 
Tt seems generally agreed, for example, that the blue crab of the 
Chesapeake is in actual course of extermination by unwise fishery 
methods, although there may not yet be agreement as to the particular 
methods which are unwise. Recently this very important question 
was referred to a conference of representatives of the two States 
concerned, together with officers of the Department of Commerce. 
The practical results of such a conference depend much, of course, 
upon the sound practical judgment and the broad spirit of those 
bearing the responsibility for determination of action; but the one 
indispensable basis of action is an understanding of the life of the 
crab. The sole hope of practical results from a conference of any 
group of persons having this problem in view rests upon such 
