Past records of the resident biologist at Bonneville Dam were 

 examined for notes concerning shad passages, mortalities, or related 

 data. Remarks concerning mortalities of shad in the fishways were 

 found for four years. They are as follows: 



19hh: 



Shad in large nuiabers passed over the dam during 

 July. Considerable difficulty was experienced at Brad- 

 ford Island in getting these fish to continue up the lad- 

 der after passing the counting station. They lay in the 

 pool above. At first only a few fish were lost against 

 the barrier, but the losses mounted until several hundred 

 a day were lost. It is conservatively estimated that some 

 300 dead were removed from the barrier during the month. 

 Every possible c^nbi nation of weir adjustment and water 

 flow was tried to induce the fish to work up the ladder. 

 Finallv, after some difficulty, the best adjustments were 

 made ±/ ^ and in a few days most of the fish had worked 

 their way up the ladder, although a few persisted in 

 remaining above the counting station, 



19h^: 



The 19h^ shad run was by far the largest ever to 

 occur at Bonneville. Shad have proved to be a most diffi- 

 cult fish to pass over the fish ladders successfully, 

 particularly above the counting stations. Above each 

 counting station there is, under normal conditions, a 

 pool of more or less quiet water of low velocity. It 

 is here that the shad like to remain and refuse to move 

 on up the ladder. Many different adjustments were tried 

 in an effort to induce the fish to move upstream. It 

 was found that the most satisfactory flow conditions were 

 a strong, direct surface flow '.jhich forced the fish to 

 swim strongly against it. Not having a resting place, 

 the fish gradually 'moved up the ladder. In the quiet 

 water, the fish would gather in large schools and swim 

 aimlessly back and forth until many of the weaker ones 

 would fall back against the barrier and die. 



1/ The best adjustments referred to in the above paragraph created 

 a strong surface flow. 



2h 



