to kind of fish passed, average size of 

 fish, and season of migration. To determine 

 the maximum entry per unit time, we planned 

 to observe the point at which a further in- 

 crease in numbers available for entry failed 

 to produce a further increase in entry rate. 



A second element to be examined was 

 the maximum number of fish (size considered) 

 that can be accommodated (i.e., provided 

 ample moving and resting space) in an indi- 

 vidual pool. If the maximum number of fish 

 that can be accommodated in a single pool is 

 exceeded, the capacity of the fishway will 

 be determined by the number of fish leaving 

 that pool per unit time. The extent to 

 which fish will accumulate in a given pool 

 will depend on (1) the number of fish enter- 

 ing per unit time (entry rate) and (2) the 

 speed at which fish pass through the pool 

 (rate of movement). If the fish move rapid- 

 ly enough and the pools are of sufficient 

 size to accommodate all fish entering, the 

 maximum accommodation of a pool may never 

 be exceeded. In this event, we should con- 

 clude that the capacity of a fishway would 

 be related solely to the number of fish 

 which can enter per unit time. 



constant for all pools, is one pool every 

 2 minutes (30 pools an hours). Thus, only 

 100 fish will accumulate in each pool, and 

 entry and exit will remain constant at 50 

 fish a minute, since maximum accommodation 

 in a pool (125) has not been exceeded. In 

 case 2, the potential maximum entry is 50 

 fish a minute and the maximum number which 

 can be accommodated in a single pool is 

 again 125 fish, but rate of movement is one 

 pool every 3 minutes (20 pools an hour). 

 Thus, each pool must carry 150 fish. Since 

 this is 25 fish in excess of the established 

 maximum number that can be accommodated in 

 a single pool, the result is that only 41 

 fish may enter and leave each pool per unit 

 time if maiximum accommodation is not to be 

 exceeded. 



Collection and Release Procedure 



Fish were collected for experimental 

 purposes in much the same manner as in 1956. 

 Fish were diverted from the Washington 

 shore fishway during peak migration periods 

 into a bypass fishway which leads to the 

 collection pool (fig. 4) at the downstream 

 end of the test facility. 



By way of illustration, we may cite 

 two hypothetical cases. In case 1, the 

 maximum entry into the fishway is 50 fish 

 of a given size per minute, the maximum 

 number which can be accommodated in a single 

 pool is 125 fish, and the rate of movement, 



It was again necessary to accumulate 

 fish for a period of time so that sufficient 

 numbers would be available for experimental 

 purposes. In 1957 the collection period was 

 confined to approximately 48 hours after 

 which preparations were made for release of 



Figure 4. — View of collection pool (foreground). Bairier 



extends 8 feet above water surface to prevent fish 

 from jumping into fishway area upstream of pool. 



