movement in the fishway, exit per unit time 

 should equal entry per unit time. 



4. There may be a point at which the 

 meiximum entry per unit time in combination 

 with a particularly slow rate of movement 

 will produce an excessive accumulation of 

 fish in the fishway. Once this condition 

 is reached, the following may result: (a) 

 maximum exit per unit time will decline 

 below maximum entry per unit time, (b) entry 

 per unit time may also decline (i.e., a 

 given number may enter a pool each minute, 

 but of these a certain number may drop back 

 out of the pool, presumably because of lack 

 of sufficient space in the pool), or (c) a 

 further decrease in rate of movement. The 

 latter may be difficult to define, but an 

 excessively slow movement coupled with high 

 density could be indicative of a crowded 

 condition impairing movement. 



Fish Collection 



To accumulate a supply of fish for the 

 capacity test, fish ascending the entrance 

 fishway were contained in the collection 

 pool until such time as it was felt that 

 sufficient numbers were on hand to conduct 

 the experiment. At the outset of these 

 experiments, our estimates of the number of 

 fish that would be required to fill the 

 fishway to capacity were necesszirily arbi- 

 trary. The only way to determine the number 

 was to conduct several experiments, each 

 time increasing the numbers collected (with 

 due consideration for size and species of 

 fish passed), if previous experimentation 

 indicated that capacity had not been reached. 

 As the experiments progressed, it became 

 evident that sever jd thousand or more fish 

 would be necessary to create or exceed a 

 capacity situation in the test fishway. A 

 collection of this magnitude occasionally 

 required that some fish be held in excess 

 of 48 hours prior to release. 



Sample counts were made on the hour 

 between 8:00 A.M. to 4:00 P.M. to obtain 

 relative estimates of the number of fish in 

 the collection pool. These were taken by 

 observing the fish as they passed from the 

 entry tunnel into the collection pool. 



Preparations for Release of Fish 



Just before the beginning of a test, 

 the entry tunnel was removed and a screen 

 was inserted in its place to prevent fish 



from backing out of the pool. Then the 

 collection pool brail was raised approxi- 

 mately 11 feet. This confined all fish 

 within a 3-foot surface layer of the pool. 

 The view in figure 6 (page 8) shows the 

 concentrattion of fish in the collection 

 pool following this operation. The purpose 

 of the above maneuver was to create a con- 

 centration of fish similar to that which 

 might exist in an actual fishway during 

 jjeriods of peak migration. 



Release of Fish into Fishway 



Shortly after the collection pool brail 

 was raised, the release gate in the picketed 

 barrier was opened to provide access to the 

 test fishway. This was considered the start 

 of the test. As the fish moved through the 

 entry gate into the introductory pool and 

 then up into the fishway, the downstream end 

 of the brail was gradually raised higher to 

 concentrate further the remaining fish in 

 the vicinity of the fishway entrance. Fig- 

 ure 7 (page 8) presents a view of the col- 

 lection pool showing the entry gate in open 

 position and with the brail tilted. 



Observation and Recording Procedure 



Immediately prior to the release of 

 fish from the collection pool, observers 

 were stationed along the walkways at points 

 overlooking the various weirs. Each observ- 

 er was provided with a push button limit 

 switch which recorded the passage of fish 

 on an operations recorder (figure 8, page 9). 

 This provided a convenient means of record- 

 ing the number of fish and the time at which 

 each passed a particular weir while the 

 experiment was in progress. 



One of our major problems in the fish- 

 way capacity experiments was to obtain an 

 accurate tally of fish passage at each 

 observation station. Counting errors were 

 particularly evident in some of the initial 

 tests before our observers had acquired 

 proficiency in counting procedure. As the 

 season progressed and the observers gained 

 experience, discrepancies in counts at 

 individual stations became less evident. 



The most difficult counting period 

 generally occurred immediately follcwing 

 the release of fish from the collection pool 

 and for a period of 10 to 15 minutes there- 

 after. During this time, observers occa- 

 sionailly had to tally over 100 fish per 



