1070 T^'- S. BUREAU OF FISHEllIES 



INTRODUCTION 



Research activities of the statf of the division of scientific inquiry 

 diirin<r 11>29 have been directed toward a sohition of the ori<j^inal 

 probhMus facin<>- the Bureau of Fisheries — the estiniatin<i of the 

 present supply of hsh. the detectin«^ of overfishing, and encouraging 

 the upbuilding of the fisheries. In addition to activities pertaining 

 primarily to the great commercial sea fisheries, important inquiries 

 have been conducted in the field of aquiculture, both as relates to the 

 propagation and culture of inland food and game fishes and to the 

 methods of farming oysters and other mollusks. 



It may not be apparent at once that all of the bureau's investiga- 

 tions of the sea fisheries bear directly ui)on the problems of determin- 

 ing the supply, of gaging or foretelling its fiuctuations in abundance, 

 or in determining methods of so regulating exploitation of these re- 

 sources that a maximum yield of products valuable as food or as 

 raw material for various industries may be maintained. Perhaps 

 the most direct approach to the question of total abundance and 

 variations in annual supply is found in the investigation of the 

 mackerel fisheries of the North Atlantic, where marked progress has 

 been made during the year in analyzing the components of the com- 

 mercial catch and in determining the relative abundance of the 

 various year classes of mackerel population. Such investigations 

 show great promise of practical application in the foretelling of the 

 abundance of future runs of fish and thus supplying information 

 of direct economic value to the fishing fleet and related shore indus- 

 tries, at the same time making it possible to guard against depletion. 

 Similar methods of study are being applied to the supplies of weak- 

 fish, whiting, scup, butterfish, flounders, etc.. that support the exten- 

 sive shore fisheries of the Atlantic coast fi-om southern New England 

 to the Chesapeake Bay. 



Corresponding to these direct studies of supi)ly on the Atlantic 

 coast are the investigations of the great salmon fisheries of Alaska. 

 Here scientific studies are providing infornudion that is rapidly 

 bringing this important source of food within complete control. 

 This promises the ultimate restoration of former abundance and 

 assures the perpetuation of the supply. 



Of less direct application, but of equal importance to an under- 

 standing of the fisheries, are such studies as the tracing of the 

 course of development from egg to adult in tiiese same species of 

 food fishes and in the many related or competing species preying 

 upon commercial forms or furnishing their food. Of still more 

 remote application, but of even more fundamental importance, is 

 the understanding of those factors in the environment that determine 

 the fate of the myriads of fish eggs deposited in the ocean waters 

 each season. O(;eanographical studies recently undertaken (lealing 

 with the currents, salinities, temperatures, and other physical and 

 chemical phenomena of the ocean waters, as well as the teeming 

 invertebrate life therein contained, all bear ultimately upon fishery 

 problems and may hold the key to the final understanding and control 

 of variations in the fish supply. 



In addition to these more theoretical researches studies on prac- 

 tical methods of fishery conservation have been conducted. For ex- 

 ample, as a result of extensive experiments in Great Lake waters rec- 



