44 REPORT OF THE COMMISSIONER OF FISHERIES. 



the natural food of young bass and other warm-water species. It is 

 of the utmost importance in connection with the subject to know what 

 plants enter directly into the dietary of the fish or contribute indi- 

 rectly to the support of the smaller animal forms that furnish food 

 for fish. In order that information might be gained on this subject, 

 which appears to have been generally neglected by fish-culturists, a 

 special assistant was employed to make a study of the conditions as 

 they existed at the Neosho station during the winter of 1919-20, 

 More extensive work along similar lines has been done by the same 

 specialist under the supervision of the division of scientific inquiry, 

 and much information of value and interest to fish culture has been 

 gathered. When this is assembled and made available for practical 

 application to the work of the stations, there is reason to believe that 

 beneficial results will follow. The natural food supply for pond 

 fishes is of particular importance, since it is very difficult to induce 

 these fish to accept the various artificial foods that are taken readily 

 by the trouts and salmons. 



The Bureau has continued its experiments looking to the develop- 

 ment of a satisfactory food for young salmonoid fish at a reasonable 

 cost for replacing the meat products in general use, the price of which 

 has advanced in proportion with 'all other commodities. Perhaps 

 the most notable results have been from the use of salmon eggs as 

 food for young salmon. These are the immature eggs taken from 

 salmon secured in commercial fishing operations, and are held in cold 

 storage until needed. Canned seal liver, a by-product of the fur-seal 

 islands, gave satisfactory results at a western station, the test indi- 

 cating that it compares favorably with pork liver. A product sold 

 under the name of " dried flies," the exact nature of which has not 

 been learned, was obtained from a New York importing firm and 

 tried as a food for trout at a number of stations, with unsatisfactory 

 results in every instance. Fishotein, a slaughterhouse preparation, 

 and clam meal have been used with some success, but neither of these 

 products appears suitable unless employed in conjunction with meat. 

 The results of all experiments thus far made, with the exception of 

 frozen salmon eggs, leave beef heart and beef liver at the top of the 

 list as the most desirable foods for young salmonoid fish. Not only 

 do they produce a more rapid growth, but the mortality is much less. 

 Of these two foods the heart seems more desirable for the early feed- 

 ing stages, while the liver is better for the more advanced fingerling 

 sizes. 



PROPAGATION OF RIVER FISHES OF THE ATLANTIC SEABOARD. 



Fishes of the Atlantic coast streams which receiA'e attention at the 

 Bureau's hatcheries are the salmon, the shad, the yellow perch, and 

 the striped bass. 



For a long period of years the Bureau has been conducting, at its 

 hatchery at Craig Brook, Me., operations addressed to the Atlantic 

 salmon. The scene of this work is the Penobscot River, which is the 

 only New England stream that now has a run of salmon, and even 

 the Penobscot maintains its salmon in the face of serious physical 

 and other handicaps. It seems to be well established that the per- 

 petuation of the salmon fishery in Maine depends largely, if not 



