REPORT OF THE COMMISSIONER OF FISHERIES. 7 



of important commercial and game fishes is to be checked, but the 

 JJureau has. nevertheless, availed itself of the opportunities occur- 

 ring to study extensively the conditions prevailing in certain por- 

 tions of the Mississippi River and to direct a special inquiry into the 

 natural history and propagation of the paddlefish. 



Coincidently with the prosecution and development of the marine 

 fisheries there is required a full understanding of the life histories 

 and migrations of the fishes involved and of the conditions of their 

 reproduction and growth. The Bureau has been attempting to sup- 

 ply the necessary data, and to this end has been conducting special 

 surveys of waters and special studies of individual fishes and groups 

 of fishes and has accumulated much valuable material. During the 

 year there was completed a report bringing together what was pre- 

 viously known and Avhat has recently been learned of the natural 

 histoiT of the fishes of one of the most important commercial fami- 

 lies, and there has been begun a compilation of the results of many 

 years of collection and study of material bearing on the life histories 

 and habits of the food fishes of the North Athintic. 



Announcement is made of the completion of the study of tlie fishes 

 of Panama as the Bureau's cooperative part in the Smithsonian 

 Biological Survey of the Panama Canal Zone. The survey was un- 

 ilertaken several 3'ears ago to lay a basis for comparison of condi- 

 tions prevailing before and after the completion of the canal con- 

 necting the two oceans. The necessity of keeping the staff of the 

 Bureau occupied upon problems of immediate importance has de- 

 layed the completion of the study of the fishes until during the past 

 fiscal year. 



MOSQUITO CONTROL HT THE USE Or FISH. 



The cooperation of the Bureau of Fisheries having again been 

 sought by the United States Public Health Service in the anti- 

 malaria campaign in southern States, an assistant was detailed, as 

 last year, to give counsel and assistance to Federal, State, and local 

 health officials concerning the use of fish for the control of mosquitoes. 

 The value of this service is attested both by the statements of health 

 officers as to the results gained and economies effected and by the 

 report of the Surgeon General of the Public Health Service. Investi- 

 gations have been continued to gain additional information as to the 

 conditions of the most effective use of fish for de.stiuction of mosqui 

 toes both in southern watere, where the prevention of malaria is a 

 primary object, and in northern waters, where mosquitoes have a 

 recognized deleterious effect upon the efficiency of labor and upon 

 property values. As a result of the inquiries conducted in the north 

 the Bureau has been able to give helpful advice to various munici- 

 palities and individuals. 



FISH-CULTURAL EXPERIMENT WORK. 



While national attention is directed to the important object of pro- 

 moting the productivity of lands, we generally takg what the waters 

 produce as a gift of nature, something to be exploited and perhaps 

 protected, but not to be cultivated. As the culture of plants and ani- 



