A study of the time of daily migration through the fish ladders 

 illustrated that peak migrations occur during the day — usually in the 

 afternconso From o\ar analysis of the data it would appear that counts 1 

 hour later than those regularly made at Bonneville would be more useful 

 for recording passage of shad. 



The fish locks^ though not regularly operated, appear to be as 

 effective as the ladders in passing shad. 



Some mortality occurred in the fish ladders and appeared to be 

 caused by a reluctance on the part of the shad to leave the quiet resting 

 pools above the counting station at high forebay levels. This can be 

 alleviated by proper adjustment of weirs and water flow in the upper 

 pools J and has been eliminated entirely by moving the counting stations 

 to forebay levels. 



In view of the success of the Bonneville fishways, it is proba- 

 ble that inaccessibility of the entrance or lack of attractive currents 

 was responsible for the lack of success in passing shad in many of the 

 early fishways. These two factors have been listed by Mugnier and 

 Swartz i' as the probable reason for failure of the two previous fishways 

 constructed at Holyoke Dam, Massachusetts. As mentioned in their report, 

 present plans for the new fish-passage facilities at Holyoke Dam include 

 an experimental phase to determine methods of inducing shad to enter 

 fish-passing devices. 



The success in passing shad over dams at Bonneville, Lackawaxen, 

 and L3.wrence demonstrates that shad can be induced to use fishways as 

 readily as do salmon. The difficulties inherent in the problem are 

 probably no grteater than similar ones already overcome for the salmonoid 

 fishes. 



LITERATURE CITED 



COLLINS, GERALD B< 



1951. A fishway that shad ascend. U. S, Fish and Wildlife Ser- 

 vice. Spscial scientific report: Fisheries No. 65. 



NEW YORK (STATE) COMMISSION OF FISHERIES. 



1891. 19th report . . , for the year 189O, 



V Mugnier, Alston D., and Albert H. Swartz. 1951. Report of the investi- 

 gations for and tentative design of the fishway at Holyoke, Massachusetts. 

 Manuscript, 



29 



