50 Ame7i,can Fisheries Society 



fishway, but the officer reported that no fish were actually 

 taken in the net ; one fish was believed to have got up and 

 escaped from the net; but that was not very certain. A 

 similar test was made not long ago by the Fisheries Bu- 

 reau at Washington, with a similar result, no fish ap- 

 peared to have found their way into the pass, nor ascend- 

 ed it and been taken in the net at the upper entrance. It 

 is said that "One swallow does not make a summer," yet 

 I am really prepared to admit that one fish would prove 

 a successful fishway. One clearly proved case of a fish 

 ascending and finding its way to the waters above the 

 fish pass would, to my mind, silence criticism. 



TWO MAIN FEATURES IN FISH PASSES. 



What are really the difficulties ? If we can decide what 

 the defects of existing fish passes are, we can try to 

 overcome them. No doctor can be expected to cure a 

 disease unless he had made a diagnosis, and decided 

 what the disease is. Most fish pass specialists have con- 

 fined their chief attention to two points: (1) Strength 

 and durability; (2) Reduction of the force or momen- 

 tum of the water coming down through the fish pass. 

 The first was important because ice and tremendous 

 floods, and floating trees and logs, would injure or carry 

 away a lightly built fish pass ; and the second is likewise 

 important because shad and alewives, and even salmon, 

 cannot work their way up a cascade of water of very 

 great momentum. 



DEFECTS OF FISH PASSES ENUMERATED. 



I think it will not be disputed that most fish passes 

 have one or more, or perhaps all, of the defects I now 

 mention : — 



(1) Ice in winter damages or even destroys them, 



(2) Floods in spring make them useless — tearing 

 parts away and filling them with debris. 



(3) At some seasons too much water, at other seasons 

 too little or even none at all, make them ineffective. 



