XXII EEPOET TO THE SECRETARY OF COMMERCE 



ichthyological studies of the fish fauna of the Gulf coast. The bio- 

 logical problems presented by the shrimp, which is supporting a 

 rapidly growing commercial fishery of vast proportion, are proving 

 particularly difficult of solution. The bureau's investigators are, 

 nevertheless, making progress in understanding the life history of 

 the three important species of shrimp. Although it would be pre- 

 mature even to outline the life history of these species, there can 

 be little doubt that the life span is short and that most of the fishery 

 draws upon dangerously young or spawning individuals. Under 

 these circumstances depletion, should it appear, may run a tragically 

 rapid course, a condition which emphasizes the importance of pro- 

 viding reasonable protection to this valuable animal. 



With a change of personnel at the Fisheries Biological Labora- 

 tory, Beaufort, N. C, emphasis has been placed upon studies in shell- 

 fish culture in the Southern States. Experimental oyster beds have 

 been established at various points from North Carolina to Florida 

 where the improved methods of culture developed in northern waters 

 will be adapted to local conditions. Physiological studies of narcosis 

 conducted at the laboratory give promise of leading to improved 

 and simplified commercial' methods of shucking oysters that will 

 effect economies in operation and improve the product. 



FISHERIES OF INTERIOR LAKES 



Major field investigations in the Great Lakes area during the 

 past year were conducted on Lakes Michigan and Huron, while 

 minor operations were carried on in Lake Erie and also in Lake 

 Champlain. The primary objective of the Lake Michigan work 

 was a study of the chub nets in order to determine their selectivity 

 with regard to chubs and their destructiveness to immature lake 

 trout. A similar investigation was conducted in the northern part 

 of Lake Michigan, in Green Bay, and Lake Huron regarding the 

 destructive action of deep crib nets, a form of gear recently intro- 

 duced into these waters and which apparently is very destructive 

 to immature fish. A study of the destiuctiveness of gill nets and 

 trap nets in Lake Erie was completed during the past fiscal year, 

 and reports are now in preparation. Limnological studies conducted 

 during the previous year with the cooperation of the State of Ohio 

 are also progressing. Pollution was demonstrated at the mouths 

 of important rivers, but the extent of conditions detrimental to fish 

 resulting from such pollution was less than had been anticipated. 



In the Wisconsin lakes detailed studies of the rate of growth of 

 various food and game fishes have been continued, and work is now 

 progressing in the analysis and correlation of a large number of data 

 collected by the bureau' and by the Wisconsin Biological and Natural 

 History Survey. 



FISHERIES OF THE PACIFIC COAST AND ALASKA 



In order to properly safeguard the salmon fishery resources pi 

 Alaska and to comply with the Wliite Act of 1924, it is essential 

 that a knowledge of the routes of migration of the important salmon 

 runs and an enumeration of the spawning fish j^assing weirs on their 

 way to headwater streams for propagation and the age composition 



