Ideally, assuming that a constant, 

 abundant supply of fish would be available 

 for each experiment, tests might be run for 

 continuous periods of perhaps 10 to 14 hours 

 and thus provide us with a basis upon which 

 to measure possible diurnal fluctuations in 

 fishway capacity. As conditions developed 

 experimentally, our supply generally became 

 exhausted — or nearly so — within periods of 

 less than 60 minutes. 



Measurement of Passage Time 

 in Fishway 



Several means of measuring rate of 

 ascent in a fishway are possible. Tauti 

 and Miyoshi (1934) expressed rate of ascent 

 in terms of "the number of fishes which 

 reach the top of the fishway in unit time 

 expressed as a percent cLge of the total num- 

 ber of fishes." While this method allows 

 for a convenient comparison between trials, 

 a measure expressing passage in terms of 

 an average time required to ascend the fish- 

 way (or in time per pool) is perhaps more 

 appropriate for the intent of these experi- 

 ments. This may be conveniently expressed 

 as minutes per pool or in minutes required 

 to ascend the 6-pool test fishway. 



The measure established for the pur- 

 pose of comparing passage time in the recent 

 capacity experiments was median elapsed 

 time. This was derived by subtracting the 

 time at which half of the total release had 

 passed the lower weir (elevation 54) from 

 the time at which half of the total entered 

 has passed the upper weir (elevation 60). 

 For example, in a given test the release 

 over weir 54 in a 1-hour period is 1525 

 fish; the median time (763rd fish) at weir 

 54 is observed at minute 15; median time 

 (763rd fish) at weir 60 occurs at minute 35; 

 median elapsed time is 20 minutes (35- 15 = 

 20) for the 6-pool fishway. This might 

 also be expressed as a rate of one pool per 

 3.3 minutes. 



Use of the median was psurticularly 

 advantageous as applied to these experi- 

 ments. For instance, it was not necessary 

 to continue jui experiment until all fish 

 entering had completed passage through the 

 fishway. Only an excess of 50 percent pas- 

 sage was necessary. Had the mean time been 

 used as a measure of rate of ascent, all 

 fish entering would have to be accounted for 

 in the exit. Also, preliminary examination 

 of passage time frequency curves (unpub- 



lished data based on the passage time of 

 individual fish) suggests a marked skewness 

 to the right with the majority of indivi- 

 duals (central values) falling in the left 

 hand portion of the curve. Use of the 

 medicin will, therefore, more adequately 

 represent the central tendency of a ssimple 

 since it is not distorted by unusual values 

 to the right of the point of maximum fre- 

 quency on the curve. 



We recognize that while the median is 

 useful from a comparative standpoint, it 

 is open to the criticism that in pratice 

 one is concerned with all the fish leaving 

 a fishway, not only the first 50 percent. 

 In these experiments from 61 to 92 percent 

 of those entering actually left the test 

 fishway within the test interval. 



OBSERVATIONS 



List of Capacity Tests 



As has been noted, our measure of capa- 

 city was to be based on a series of tests 

 beginning with trials involving relatively 

 small numbers of fish and continuing with 

 gradually increasing numbers introduced in 

 each trial until capacity was reached and 

 could be effectively demonstrated. Much of 

 our initial effort (trials 1 through 6) was 

 confined to the development and refinement 

 of experimental procedure and techniques. 

 Data obtained during these early tests were, 

 therefore, subject to a variety of condi- 

 tions which were not always comparable. 

 However, the data are included for examina- 

 tion, since they provide a fund of back- 

 ground information which may be basic to 

 the examination of fishway capacity. 



In all, eight capacity tests were con- 

 ducted during the period May 22 through 

 September 7, 1956. A summary of these tests 

 is given in table 1 (page 12). Total num- 

 bers released in an individual test ranged 

 from 70 to nearly 3000 fish during a 1-hour 

 period. The test involving the largest 

 number of fish (July 13) was not, however, 

 the leirgest when considered in terms of 

 total weight. A conversion to estimated 

 poundage shows the weight of the fish in 

 the September 7 test was more than double 

 that in the July 13 test (13 pounds x 1515= 

 19,695 pounds as compared to 3 pounds x 

 2886 = 8,658 pounds). 



11 



