266 Roosevelt Wild Life Bulletin 



parent depletion, whether by outlet or some other way should first 

 be learned by competent investigation before going to the expense. 

 In one instance known to the writer, a practicable fishway would be 

 more effective in maintaining the stock than a screen. In another 

 a screen erected at the stated cost of $30,000 is absolutely ineffective 

 in maintaining the stock, and unnecessary too, for the nature of the 

 fish concerned is not to leave the lake in considerable numbers ex- 

 cept for spawning. In this case if the fish did go into the outlet in 

 numbers sufficient to deplete the lake an effective screen would be 

 justifiable, as the fish having gone into the outlet cannot get back. 

 But that this lake continued to be well stocked before there was 

 even a dam in the outlet indicates that a screen is unnecessary. 

 Furthermore, this particular screen, as is the case with most screens, 

 while it might prevent the egress of grown fish would not prevent 

 the passage of young fish should they attempt to descend. 



Another instance is that of a natural landlocked salmon water. 

 In former years the outlet was a famous and favorite fly-fishing 

 resort ; and but few fished in the lake. Also the outlet was the 

 principal breeding place for the fish, in fact practically the only one 

 of considerable consequence. The final erection of a new dam with 

 an impracticable fishway, prevented the return of any salmon which 

 succeeded in gaining the outlet. The natural spawning grounds 

 were also cut off. However, the latter was considered of minor 

 importance as for many years the descent of breeding fish had been 

 obstructed by nets and the fish taken for artificial propagation. The 

 apparent decline of salmon in the lake caused a demand for a 

 screen, which has been installed. It prevents the descent of adult 

 fish, excepting perhaps during log drives, but not of the young fish. 

 It is not known that the young go down, but there is evidence that 

 the screen has not produced the desired results. 



The fact is that no investigation concerning the alleged decrease 

 of fish, in any of the waters mentioned, has ever been made. If the 

 cost of the screen in any instance had been devoted to investigation, 

 practical results might have been achieved. 



Stocking and Restocking Problems. A body of water is usually 

 stocked for one or the other or both, of two purposes, namely, for 

 . food supply or to afford sport. 



No small body of water can afford an unlimited supply of food 

 fish. If a market fishery is carried on in inland waters for sport 

 fish, it is impossible for the stock to be naturally maintained. In many, 

 if not all instances, even considered from the sport-fish side, the 

 stock cannot prove self-sustaining save by rigid restrictions and 

 regulations from the beginning to the end ; so rigid indeed that it 

 becomes almost, if not quite impossible to afford satisfactory fish- 

 ing to an increasing number of anglers, and after all, recourse must 

 be had to outside sources of supply. 



It might be possible to so manage large bodies of water that they 

 would afford both commercial and sport fishing, but as a rule each 

 class of fishing must l^e restricted to different species. As 



