PROPAGATION AND DISTRIBUTION OF FOOD FISHES, 1923. 23 



the protecting film of the shell is apt to be broken, forming a fertile 

 field for bacterial growth. It is believed this subject is worthy of 

 careful study in an effort to overcome the heavy losses of eggs 

 annually occurring at most of the stations of the bureau. 



HATCHING EGGS IN GRAVEL. 



Some interesting experiments in the hatching of trout eggs in 

 gravel were conducted in the course of the year at the W^^theville 

 (Va.) station. On January 4, 6.600 eyed rainbow-trout eggs were 

 buried in sand and gravel in one of the rearing ponds. This ma- 

 terial was obtained from a neighboring creek and was not screened, 

 though the larger stones were removed. No fish having been ob- 

 served by February 27, the covering was removed and washed and 

 all the eggs were found to be dead. 



In another experiment, undertaken on January 5, a trough was 

 prepared with ciTished stone sifted through a coarse-mesh screen to 

 exclude the fine particles. Four nests were made with the larger 

 pieces of stone, and in each of these eyed eggs to the number of 

 944 were scattered and covered to a depth of about 3 inches with 

 the sifted material. A few fry in the advanced stage were observed 

 in the trough on February 10, and the remainder of the hatch came 

 out of the nests within the next two weeks with the sac nearly ab- 

 sorbed. On February 20, when the nests were removed and the 

 fingerlings counted, it was ascertained that 2,736 of the 3,736 eggs 

 planted had hatched. 



COMMERCIAL FISHES. 



Of the 71 stations and substations engaged in the fish-cultural 

 operations of the bureau, the work of 44 was devoted mainly to 

 propagation and to the salvage of certain commercial species. 

 Among the most important fishes handled, from a commercial view- 

 point, were the salmons of the Pacific coast, the whitefishes, lake 

 trout, and cisco of the Great Lakes, and the cod, haddock, pollock, 

 and winter flounder of the Atlantic coast. Other species of lesser 

 commercial value were handled on a smaller scale. The results of 

 the work at tliese stations show a considerable decrease as compared 

 with those of the previous year, most of the falling off occurring 

 among the Atlantic coast species. The principal reason for the de- 

 cline was the unusually severe weather prevailing during the spawn- 

 ing period, though lack of funds for the efficient prosecution of the 

 work at all points was also responsible in some degree. 



PACIFIC SALMONS. 



Fish-cultural operations coming under this head are conducted ex- 

 tensively at 19 stations and substations located in Washington, Ore- 

 gon. California, and Alaska. Operations at this group of stations 

 are devoted almost exclusively to the propagation of the salmons of 

 the Pacific coast, though small numbers of trout eggs, transferred 

 from other stations of the bureau, are usually hatched annuallv at 

 two or three points in Oregon to supply the local demands for' fish 

 of that character. The results attained in the salmon work during 



