Table 1. --Numbers of fish entering, leaving, and present 

 in the lowest fishway pool during each of the 

 first 30 minutes of a teet interval. 



tests. However, one test can yield useful 

 information. 



2000 4000 6000 



Average Number Present 



Figure h. — Relationship between exit rate 

 and number present In a fishway section 

 during a period of constant entry rate. 



SUNMARY AND CONCLUSIONS 



We have set up a simple model (assum- 

 ing average usage time is independent of 

 average number present) for determining, 

 under appropriate experimental conditions, 

 whether the internal capacity of a fishway 

 is exceeded. Capacity as defined here 

 occurs when the observed values are higher 

 thcui the values given by the model. At 

 present we have no data against which to 

 test this model. 



For an interval of reasonably stable 

 entry rate one also may judge whether 

 crowding obstructs passage through a fish- 

 way section. This occurs when the rela- 

 tionship of exit rate to numbers present 

 decreases significantly. This is demon- 

 strated with actual data. 



Any judgment about capacity or delay 

 requires a rather complex experimental 

 situation; the section on Experimental Com- 

 plications explains a few of the problems. 



We expect that the rationale given 

 here will be refined and extended. In the 

 meantime, the reader may find these con- 

 cepts useful starting points in experimen- 

 tal work in which crowding is a factor 

 under study. 



liherature cited 

 elling, carl h. , and howard l. raymond 



1959. Fishway capacity experiments, 



1956. U. S. Fish and Wildlife 

 Service, Special Scientific 

 Report — Fisheries No. 299. 26 p. 



PRETIOUS, E. S., L. R. KERSEY, AND 

 G. P. CONTRACTOR 

 1957. Fish protection and power devel- 

 opment on the Eraser River. 

 University of British Columbia, 

 Vancouver, B. C. , Fraser River 

 Hydro and Fisheries Research 

 Project. 65 p. Appendices A, 

 B, and C. Processed. 



INT.DUP.,D.C.59- S(a2| 



