The timing zone (A to B, fig. 1) extended from 

 the release compartment (A) to the exit area (B) 

 at the upper end of the channel. A deflecting 

 grillwork (fig. 3) directed fish toward an observation 



Figure 3. — Exit area of test channel viewed from above. 

 Grill on left foreground deflects fish toward view'ing area 

 (arrow) of submerged observation chamber. Flow is 

 toward foreground. 



cent confidence intervals about the median (Dixon 

 and Massey, 1957) were applied to test for signi- 

 ficance of differences between passage times at the 

 two velocities. As used here, the median is the 

 passage time of the median fish of all fish tested in 

 each group, including those fish that failed to com- 

 plete passage within the arbitrary 45-minute time 

 limit. Computations of the mean passage time 

 include only those fish that completed passage of 

 the test channel within 45 minutes. 



PASSAGE TIME IN RELATION TO 

 WATER VELOCITY 



Comparisons of time ret[uired to pass through 

 the test channel at the two velocities are given by 

 species in the following subsections. 



CHINOOK SALMON 



Tests with chinook salmon were made during two 

 periods— May 8-11 and June 12-15, 1962. Fish in 

 the early period are normally called spring-run and 

 those in the latter period, summer-run chinook 

 salmon. Median passage times in the May test 

 at water velocities of 1 and 2 f.p.s. were 3.4 and 3.9 

 minutes, respectively (table 1). Results of the June 

 test were similar. Median passage times in the 

 two velocities did not differ significantly between 

 velocities or between tests. Mean passage times, 

 given for comparison, suggest similar trends. In 

 both tests, however, chinook salmon took slightly 

 more time to pass through the channel at 2 f.p.s. 

 than at 1 f.p.s. (fig. 4). This difference corresponds 

 with observations by Weaver (1963), who found that 

 chinook salmon moved more slowly as velocity in- 

 creased in the range of 2 to 8 f.p.s. 



window at the point of exit. This arrangement 

 ensured accurate observation and timing of the 

 fish when visibility was limited owing to turbid 

 water. The time of entry and exit for each fish 

 was registered on a special time-event recorder. 

 If a fish had not completed passage of the channel 

 within 45 minutes after time of entry, it was removed 

 and anotiier fish was introduced. 



ANALYSIS OF PASSAGE TIME 



The effect of water velocity on fish passage was 

 determined by measiu'ing the time required for the 

 fish to pass through the channel. Ninetj'-five per- 



T.\BLE 1. — Median and mean passage times of chinook salmon 

 in an experimental transportation channel at Bonneville 

 Dam at water velocities of 1 and 2 f.p.s., May and June 1962 



' 95-percent confidence intervals about the median. 



' One fish failed to complete passage within the 4.5-minute time limit 

 and was not included in computation of the mean. 



TR.\XSPORT.^TION CHANNELS FOR SALMONIDS 



61 



