44 KEPOET OF COMMISSIONER OF FISH AND FISHERIES. 



success ill restocking the rivers of the Atlantic slope with the shad, did 

 a work of far greater importance than he with other fish-culturistshave 

 done in the propagation of trout. 



The cod, mackerel, herring, white-fish, shad, salmon, and salmon-trout, 

 deserve the principal attention in the efforts at increase. 



With the three first-mentioned artificial propagation has nothing to 

 do at present; probably nev^er will. Of the others the white-fish is the 

 most important as a food-resource,, because of its numbers and because 

 it can be obtained at all seasons of the year. 



In adaptability to artificial propagation it is probable the shad has 

 the advantage because of the rapid development of the eggs. But there 

 is still a difficulty in the way of the propagation of an unlimited num- 

 ber of shad, in the fact that the streams to which they formerly resorted 

 are obstructed by numerous and high dams. There are no obstructions 

 of this character to interfere with the white-fish ; and in the great lakes, 

 if it were advisable, there is nothing apparent in the way of the propa- 

 gation of unlimited millions. 



The character of its food has also a bearing on its adaptability to rapid 

 increase. There is considerable loss among the speckled trout from 

 the larger ones preying upon the smaller. In England the salmon have 

 been accused of the same habit to some extent, while the young are in 

 the parr and smolt stage. But nothing of this kind will ever deplete 

 the numbers of the white-fish. Invertebrate, forms of life constitute its 

 entire food. To some extent it will suffer from the rapacity of other 

 fishes, but, as shown on other pages of this report, in a state of nature 

 the ova-stage is the one in which the greatest loss is suffered. 



(22 h.) The food of the white-fish. — The food of the white-fish has been 

 a problem inciting numerous conjectures among fishermen, sportsmen, 

 and fish-culturists, and baffling the investigations of a few naturalists 

 for a number of years past. 



To Dr. P. E. Hoy, of Eacine, we think belongs the credit of first dis- 

 covering correctly the character of their food. On opening the stomachs 

 of numerous white-fish he at first failed to determine the character of 

 the stomach-contents, until, after washing the half-tligested mass in a 

 basin of water, he found the sediment to be full of small Crustacea^ whose 

 existence in the lake had never before been suspected. 



M,y examination and preservation of the stomach-contents from all 

 quarters of the lakes confirmed- Dr. Hoy's observations, and discov- 

 ered a few other small forms of life as the food of white-fish. 



The invertebrates found were of crustaceans : species of the families 

 Gammaridcv and Mysidw; of the mollusks: species of the genus Fisidium; 

 and certain insect larvae. 



A few fish-ova were frequently found in the stomach, and it was not 

 unusual to find a little gftivel. 



In the greater portion of the lake the Gammaridm constituted the 

 principal food. In shallow regions small Conchifers were more uu- 



