528 EEPOET OF COMMISSIONER OF FISH AND FISHERIES. 



species many years ago, and it has since increased to a very large extent, 

 and affords a considerable income to the owners of the property on the 

 lake who control the fisheries. 



The salmon or lake trout. — A considerable number of this species, 

 {Salmo namaycusli,) obtained in Lake Ontario was introduced into 

 Newfound Lake, New Hampshire, in 1871, by the State commissioner. 

 In 18GG a number of land-locked salmon, {Salmo sehago,) had been 

 brought to this lake from the St. Croix River. 



The hrooJc-trout. — The brook- trout, {Salmo fontinalis,) the favorite of 

 anglers, ha«, of course, received much attention in this direction. 



There are numerous instances related of their being introduced into 

 new waters from neighboring streams. Even in the interior of the coun- 

 try they have been transferred southward among the drift ridges and 

 prairies from the more northern rocky streams of Michigan, Wisconsin, 

 and Minnesota. Generally this has been done for the purpose of stock- 

 ing breeding-establishments. 



A stream at Lake Forest, in Northern Illinois, flowing from an arte- 

 sian well, was supplied with live trout brought from Wisconsin, biit 

 none of them lived, probably because of the high temperature of the 

 water. The distribution of this species from breeding-establishments 

 has been very extensive. 



.3. — THE TRANSFER OF NATURALLY-DEPOSITED EGGS. 



Spawning races. — Of the second method there has been comparatively 

 little application in the United States. 



The experiments in hatching black bass by placing the pairs in a box 

 similar to the one used by Lund in 1760, and the methods employed f©r 

 obtaining trout-spawn originated by Ainsworth and Collins, are of this 

 character. 



The simple apparatus employed by Mr. Ainsworth was merely an ad- 

 justable section in a narrow raceway constructed in such a situation as 

 would induce the trout to enter from the deeper water for the purpose of 

 digging their nests. A screen of coarse-wire cloth covered loosely with 

 gravel constituted a false bottom to this box, through which the eggs, 

 on emission, fell to the real bottom below. 



The Collins apparatus was an improved modification of this principle, 

 inasmuch as it obviated the necessity of disturbing any portion of the 

 raceway, the eggs falling through the upper screen upon a revolving 

 apron, or wide belt of wire cloth beneabh, when, by turning the drums 

 on which it rolled, the eggs were carried to one end, and fell over into 

 pans placed to Catch them. 



The greater percentage of fertile eggs from artificial impregnation 

 has induced, in later years, very little use of these methods, except 

 where it is regarded as desirable to avoid the cold and often severe 

 exposure to the person impregnating eggs in cold weather. 



