was no appreciable mortality. In recent personal correspondence, I 

 have learned that there i/as very little mortality in 195l, and since 

 early 1952, when both counting stations have been located at forebay 

 level, little or no raortality has been observed. It can be con- 

 cluded from these reco^-ds that the probable cause of the shad mortal- 

 ity was the effect of ini.nical hydraulic conditions in the fishways 

 resulting from the installation of the counting stations in the 

 ladders. Apparently after experimenting with various adjustments for 

 high water levels, conditions were improved beginning with 19h3, and 

 now that the counting stations have been installed at forebay level 

 these adverse conditions have been eliminated. 



Presumably it is the opinion of fish.;ay observers at the dam 

 that many shad enter the ladder but do not reach the counting fence 

 (U.S. Army, Corps of Enf;ineers, 19^0) , Itie numbers or percentage of 

 these is not knovm, of coirse, since the only counts of fish in the 

 ladders are those made at the counting stations near or at the upper 

 end of the fishways. As mentioned earlier, it is entirely possible 

 that the shad do not have much incentive for ascending the fish ladders 

 since there is so mucl" available spawning area below the dam. It is 

 also possible that construction of the dcm at this point in the river 

 usurped a formerly important spawning area, and thersfore there may be 

 no motivation for the shad to progress farther upstream. 



All the fish found dead against the barrier below the pool 

 during the 19I?C season were examined. Beth females and males were 

 found. The males irere all sexually maturf^, while the females were in 

 all stages of sexual maturity aw^ ore was about 5o-percent spawned out. 



To determine whether the shad spavm in the resting pool, 

 a plankton net was set three different times in the pool beloX'J the 

 counting house for l6 hours during:- the afternoon and night. On one 

 occasion five shad eggs were recovered. Since it is possible that 

 these eggs may have floated down from upriver, the results are not 

 conclusive, 



Swinming Activities within the Ladders 



In the fish-ladder pools in which there is a strong downstream 

 surface flow (usually referred to as the "streaming" type of flow), shad 

 exhibited essentially the same swimming motions as do the other species. 

 That is, they face upstream into the current^ work their way to the head 

 of the pool, and then swim up over the weir into the next pool. In this 

 way the;/ proceed up the ladder and over the dam. 



26 



