80 



70 



o 



O 60 



I- 50 



_i 

 < 

 I- 

 o 



(- 



u- 40 

 O 



< 



z 30 

 tij 

 o 

 cr 



UJ 



a. 

 20 



10 







Flow 



^ 



I 



1 



I I 4 



I 



^ 



2 : 3 



POOL QUADRANTS 



Plunging Flow 

 ^^ Streaming Flow 



UNKNOWN 

 Figure 7, — Pool areas used during plunging and streaming flows. 



2 3 4 



QUADRANT USED 



(C) circuitous passage with a rest period. The 

 direct in-line passages were brief, generally 

 about 12 seconds. Circuitous passages that 

 included continuous movement were slightly- 

 longer but usually less than 45 seconds. Cir- 

 cuitous passages involving a rest period were 

 nearly always longer, usually more than 

 1 minute , 



The movement of each fish was plotted 

 by transferring the taped observations to a 

 sketched outline. The three basic types of be- 

 havior in plunging and streaming flows are 

 illustrated diagrammatically in figure 8. Move- 

 ments of individual fish differed greatly. Many 

 of the charted movements were too complex 

 for diagrammatic presentation. 



Orientation of fish before exit from the pool 

 usually was in line with the strong directional 

 flow at the base of the weir overfall. During 

 plvmging flow, the fish usually aligned them- 

 selves either diagonally or almost vertically 

 in the overfall jet at about middepth in the 



pool (fig. 8). When flows were streaming, the 

 fish approached the surface of the pool and 

 aligned themselves almost parallel to the 

 floor in the strong surface flow. This differ- 

 ence in orientation vinder the two types of 

 flow was characteristic of all fish regardless 

 of other aspects of the basic behavior (A, B, 

 or C). 



Fish were relatively inactive at times under 

 both conditions of flow. Positions of rest, 

 usually near the bottonn of the pool, showed 

 that fish faced the prevailing current. Thus, 

 during plunging flow they were aligned toward 

 the upstream end of the pool in quadrant 2, 

 and during streaming flow theyfaced the down- 

 stream end of the pool in quadrant 3 (fig. 8C), 



Chinook salmon did not favor a particular 

 type of behavior (i.e.. A, B, or C) in either 

 plunging or streaming flow. Observations listed 

 in table 3 were tested by chi- square contin- 

 gency for frequency of behavior patterns vmder 

 each condition and between flows. Behavior 



