22 REPORT OF THE COMMISSIONER OF FISHERIES. 
return to the main river channels. The permanent employees of the 
Bureau, supplemented by a force of temporary men, were organized 
mto units equipped with boats, seines, and vessels for holding the fish, 
and the most productive river sections were systematically covered 
in the manner fully described in previous reports. When the opera- 
tions were brought to a close on November 10, the number of fishes 
rescued and replanted had reached 120,656,420, consisting of catfish, 
buffalofish, carp, black bass, sunfish, crappie, and other food fishes 
of the region. 
The striking results, undoubted benefits, and low cost of this work 
commend it to everyone familiar with it and warrant its extension 
over all parts of the Mississippi Valley where flood waters become 
cut off from the main streams. There are both opportunity and need 
for the annual salvaging of untold millions of food fishes in this 
region, and the Bureau has noted with great satisfaction the passage 
by the House of Representatives of a bill giving formal recognition 
of this intensely practical work and making financial provision for 
enlarged facilities and personnel for its prosecution. 
DISTRIBUTION OF MOSQUITO-EATING FISHES. 
The fish-cultural service has been called on to supply lots of the 
mosquito-eating fish Gambusia for consignment to foreign countries. 
The fish were collected at several southern stations and were desired 
because of the success that has attended their employment in this 
country in eradicating malarial mosquitoes. 
In response to requests from the League of Red Cross Societies, 
with headquarters in Geneva, Switzerland, shipments of these little 
minnows were made to Italy and Spain, and pursuant to a request 
coming through the usual] diplomatic channels, a consignment was 
furnished for the Government of Argentina. A lot supplied to the 
international health board was destined for Porto Rico. All these 
fish were intended to be used in antimalarial work. 
Inasmuch as the top minnows can be grown in the reserve ponds 
of various southern stations or-collected in near-by waters at little 
or no expense, it seems proper for the Bureau to be in position to 
meet reasonable demands for this fish, especially in view of the active 
participation of the Bureau in recent campaigns for the eradication 
of mosquitoes by the use of this species. 
ARTIFICIAL PROPAGATION OF FRESH-WATER MUSSELS. 
Under the general direction of the fisheries biological station at 
lfairport, Iowa, extensive work has been done, as heretofore, in the 
propagation of pearly mussels native to the Mississippi River and 
tributaries. During the fiscal year 1921, 169,740,050 glochidia, or 
larval mussels, in a condition of parasitism on fishes, were liberated 
in public waters, as compared with 183,021,720 in the previous year. 
The fish hosts used for inoculation with glochidia were salvaged from 
overflowed waters, chiefly in the vicinity of Fairport, Iowa, and New 
Boston, Ul. The number of fishes rescued was 976,550, of which 
40,020 were adults, and the number infected with the glochidia of 
appropriate mussels before being liberated was 50.268. 
