Adirondack Beaver 149 



and streams. About this whole subject however, little can be said 

 that rests upon a basis of established fact, and until it has been 

 carefully investigated all that can be said about it must be accepted 

 merely as expression of opinion, based upon evidence that is largely 

 circumstantial. Two opposing views were encountered : one main- 

 taining that the presence of beaver is distinctly harmful to trout; 

 the other that it is beneficial. The conflicting opinions represent, 

 I am sure, honest convictions gained by different experiences ; and 

 it is highly probable that there is some truth in both views ; that 

 in some situations the results may be harmful and in others bene- 

 ficial and under other conditions the effect may be neutral. 



Arguments Against the Beaver in Relation to Trout. The 

 harmful effects of the beaver upon Adirondack trout has been dis- 

 cussed by former Commissioner George. D. Pratt ('21, pp. 117-118). 

 This adverse opinion was probably that of John W. Titcomb, the 

 Fish Culturist of the Conservation Commission at that time. See 

 also The Conservationist, Vol. 4, p. 173. These effects are sup- 

 posed to arise in three ways : ( 1 ) by dams acting as barriers to the 

 movements of trout; (2) by excessive warming up of the water in 

 the beaver ponds; (3) by the changing character of the water itself 

 in the beaver ponds, — possibly rendered toxic to a sensitive fish like 

 the trout. 



1. Beaver Dams as Barriers. Where beaver dams in consider- 

 able numbers occur on a trout stream it is believed that the fish 

 will be unable to surmount these barriers when in the fall of the 

 year they seek their spawning grounds upstream. This is supposed 

 to be true, especially in the case of the higher dams, but just how 

 high a dam it takes to prevent trout from passing to the pond 

 above is not known. If dams do deter trout from ascending, then, 

 no doubt, a great many are penned in between dams all along the. 

 stream. A beaver dam with its projecting sticks and boughs 

 obviously presents a different and more difficult obstacle from that 

 of a low natural fall or rapids. 



2. Effect of Flows on Temperature of Water. When the trees and 

 bushes in a beaver pond die, the summer sun is given unobstructed 

 play upon an expanse of shallow water. In these ponds changes 

 of water are slow because of the arrested current. The heating pro- 

 cess is aided by the evaporation which tends to keep the water at a 

 low level. The cool water of springs feeding into the ponds is 

 neutralized, the springs being "killed," according to a local expres- 

 sion. 



