■o 14 



- 12 



810 



E 4 



Y = 172.71 + .O336X 



• 2 



I = May I 



2 = May 8 



3 = Jure 25 (a) 



4 : June 25 (b) 



5 : June 25 (c) 



"7- 



-T- 



4 8 12 16 20 24 28 

 Pounds avoilable in thousands 



32 



Figure /.--Relation between initial availability and maximum 

 entry rate during five 1557 fishway capacity trials. Num- 

 ber of fidi expressed in pounds. 



initial control on the cap 

 will be the number of fis 

 per unit time. Once the 

 it becomes important to e 

 to which they may accumul 

 Maximum numbers of fish 

 test fishway during the f 

 are given in table 3. Al 

 the observed maximums in 

 the fishway. 



acity of a fishway 

 h which may enter 

 fish have entered, 

 xamine the extent 

 ate in the fishway. 

 observed in the 

 ive 1957 trials 

 so included cire 

 the first pool of 



Tests 1 and 3 are of greatest interest 

 since the observed maximum number of fish 

 (size considered) in the fishway in these 

 tests was usually nearly double that noted 

 in the other three trials. Test 1 shows 

 that for fish (predominantly spring chinook 

 salmon) averaging 14 pounds in weight, the 

 maximum number observed in the first pool 

 was 148 fish and the maximum in the fishway 

 was 640, an average of 107 fish per pool. 

 Apportioning these figures on the basis of 

 available space (388 cu. ft. per pool), 

 there was 1 fish per 2.6 cu. ft. in the 

 first pool, and the average for 6 pools was 

 1 fish per 3.6 cu. ft. Similarly, in test 

 3 in which the fish (chinook, blueback, and 

 steelhead) averaged 9.2 pounds, there was 

 1 fish per 2.2 cu. ft. in the first pool, 

 and the average for the fishway was 1 fish 

 per 4.5 cu. ft. 



higher. This may be explained by the fact 

 that the fish in test 3 ascended the fishway 

 almost twice as rapidly as those in test 1. 



As used here, the analysis of space 

 per fish has considered the entire pool 

 volume (388 cu. ft.) to be available to the 

 fish. In all likelihood, not all of the 

 pool will provide suitable moving and rest- 

 ing areas, and, as such, may never be uti- 

 lized. Until we actually know how large 

 numbers of fish distribute themselves within 

 a fishway pool (this will require a series 

 of observations through viewing windows on 

 the sides of pools), the present method of 

 assessing space per fish must be considered 

 with some reservation. 



For complete data on the number of 

 fish present in the fishway at a given time 

 during the five trials, see table A-3 in 

 the appendix. 



Table 3. — Observed maximum number of fish in fishway 

 C6 pools) and in first pool, average 

 weights, and space per fish. 



A number of factors may conceivably 

 influence the rate at which fish ascend 

 fishways. Some are inherent in the fishway 

 structures; others may be related to envi- 

 ronmental and biological conditions. Ex- 

 periments at Bonneville have shown, for 

 instance, that the speed at which certain 

 species move in fishways may vary with 

 season. Chinook salmon required more than 

 twice as long to ascend a 6-pool, l-on-16 

 slope fishway in spring as in late summer— 

 Conceivably, temperature and turbidity of 



5/ 



Actually, fewer fish accumulated in 

 the fishway during test 3 than during test 

 1, even though the entry per unit time was 



5/ Monthly progress reports Nos. 10, 14, and 22 on research on 

 fidiway problems conducted at the Fisheries-Engineering 

 Research Laboratory at Bonneville Dam under Contract No. 

 DA-35-026-25142 with the U. S. Fish and WUdliie Service. 



