REPORT OF THE COMMISSIONER OF FISHERIES. 51 



attention, and those obstructive to the development of the industry- 

 are being solved. 



Congress passed an act, approved June 12, 1917, authorizing the 

 Bureau to conduct a careful investigation in this field. This act car- 

 ried an appropriation of $10,000 to enable the Bureau of Fisheries, 

 in cooperation with the Bureau of Standards, to develop new aquatic 

 sources of supply of leather. 



PROPAGATION AND DISTRIBUTION OF FOOD FISHES, 

 * GENERAL REVIEW OF OPERATIONS. 



Conspicuous success and progress have characterized the year's work 

 in fish culture. While the output of several of the important species 

 was less than the average in recent years, the aggregate output was 

 larger than in any previous year, the increase over 1916 being some- 

 what more than 6 per cent. Among the fishes produced in about the 

 same numbers as m 1916 were shad, whitefish, silver sahnon, chum 

 salmon, rainbow trout, and brook trout. Species whose output was 

 smaller were chinook salmon, sockeye salmon, grayling, smelt, black 

 bass, pike perch, yellow perch, white perch, cod, and lobster. In- 

 creased production was secured in the case of catfish, buffalofish, silver 

 salmon, humpback salmon, steelhead salmon, Atlantic salmon, land- 

 locked salmon, lake trout, striped bass, pollock, and winter flounder. 

 The somewhat detailed discussion w^hich follows shows the reasons 

 for the gains and losses in the different fields. The total output was 

 5,158,963,295, compared with 4,847,262,565 in 1916. 



Following is a summarized table showing the number of fish eggs 

 and fish distributed by the Bureau in the past year. Most of the 

 eggs herein noted were transferred to various State hatcheries. 



