REPORT OF THE COMMISSIONER OF FISHERIKS. ' 
of important commercial and game fishes is to be checked, but the 
Bureau 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 what has recently been learned of the natura! 
history 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 Atlantic. 
Announcement is made of the completion of the study of the fishes 
of Panama as the Bureau’s cooperative part in the Smithsonian 
Biological Survey of the Panama Canal Zone. The survey was un- 
dertaken several years 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 BY THE USE OF 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 destruction of mosqui- 
toes both in southern waters, 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 take 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- 
