Table 5. --Remainders obtained by subtracting the percentage 

 of salmonids entering a given orifice when it was on the 

 north side of the experimental system from the percentage 

 of those entering the same orifice when it was on the 

 south during each test period 



[Asterisk, denotes a mean difference than was significantly 

 greater (95 percent level) than zero] 



22.23* 



2l*.05* 



32.92* 



'■ All of the other values shown are positive. 



use of a full 2-day test period for each set 

 of conditions compared. 



Treatment of the data was based on our 

 assumption that position of the laboratory- 

 equipment caused more fish to enter the south 

 orifice than the north. This assumption may 

 be erroneous. If so, more accurate percent- 

 ages of fish entering a given orifice would 

 be obtained if the fish that entered on the 

 south side--regardless of the orifice pre- 

 sented there--were removed entirely from 

 consideration. The results of tests shown 

 in tables 1-4 are changed by this treatment 

 only for coho salmon under test condition 3 

 (shallow horizontal vs. deep horizontal). The 

 trend toward higher use of the shallow hori- 

 zontal orifice by coho salmon shown in the 

 first treatnnent is changed to a significantly 

 greater use of that orifice by the second 

 treatment. 



INTERPRETATION 



Since volume and velocity of attraction flows 

 were all equal, our analysis of the response of 

 fish under the different conditions considers 

 only the position of the orifices. The four 

 test conditions comprise four experiments on 

 different aspects of orifice use. Each experi- 

 ment can be examined individually by sta- 

 tistical techniques, but results of the different 

 experiments cannot be combined and examined 



by the same techniques for a common analysis. 

 Rather, the general pattern of use must be 

 deduced by inspection of the results of the 

 four experiments. We feel that the following 

 deductions of what might have happened in 

 the introductory area can be useful in de- 

 veloping new hypotheses for future testing. 



Taking into consideration all of the mate- 

 rial available to us in the tests with chinook 

 salmon and steelhead trout, we have developed 

 the following rationale: A substantial number 

 of migrating chinook salmon and steelhead 

 trout evidently approached the test panel in 

 the introductory pool at depths between 3 

 and 9 feet. If an orifice was present in their 

 plane of travel, they entered at that level. 

 This is indicated because it was not possible 

 to demonstrate a significant difference between 

 use of shallow and deep vertical orifices, but 

 a significant difference was found between 

 shallow and deep horizontal orifices. If an 

 orifice was not present in their plane of 

 travel, migrants presumably searched upward 

 and laterally beyond the first passable open- 

 ing encountered. This is indicated by greater 

 use of the horizontal orifice centered at 3 

 feet than the one centered at 9 feet, and for 

 the inconsistency between replicates when 

 vertical and horizontal orifices were centered 

 at 3 feet. If a downward search was required, 

 its lateral aspect presumably terminated at 

 the first passable opening encountered. This 

 is indicated by the greater use of the vertical 

 orifice when vertical and horizontal orifices 

 were centered at 9 feet. 



The laboratory facilities provided a reason- 

 ably deep approach area (19 feet) but the depth 

 range of the orifices was limited to 9 feet 

 because of the existing sill of the transporta- 

 tion channel. Deeper submergence of orifices 

 may have produced more clear-cut responses, 

 particularly in comparisons of the response 

 to vertical orifices at shallow versus deep 

 positions. 



In the application of these results to a proto- 

 type, the effect of competing turbine dis- 

 charges must be considered. Because the 

 turbines discharge at depths beneath existing 

 collection-channel ports, it is possible that 

 competing attraction flows (i.e., turbine vs. 

 collection-channel discharges) might influence 

 the vertical distribution of fish as they ap- 

 proach a powerhouse collection channel. This 

 situation could produce results somewhat dif- 

 ferent from those noted in the laboratory, 

 where the effect of the turbine discharge was 

 not a factor. 



We must emphasize that we studied 

 salmonids that were actively moving up- 

 stream, and that all orifices, regardless of 

 shape or location, were entered by at least 

 some members of every species observed 

 on any day. 



