Response of Migrating Adult Salmonids to 



Vertical and Horizontal Rectangular 



Orifices at Two Depths 



By 



CLARK S. THOMPSON, WILLIAM SPENCER DAVIS, 

 and EMIL SLATICK, Fishery Biologists 



Bureau of Commercial Fisheries, Fish-Passage Research Program 



Seattle, Wash. 98102 



ABSTRACT 



The response of migrating adult salmonids to various placements of rectangular 

 fishway orifices was studied at the Fisheries-Engineering Research Laboratory, on 

 the Washington end of Bonneville Dam. Chinook salmon ( Oncorhynchus tshawytscha ), 

 steelhead trout (Salmo gairdneri), and coho salmon (O. kisutch ) approaching a verti- 

 cal wall had the alternatives of entering rectangular orifices positioned either hori- 

 zontally or vertically and either shallow (3 feet) or deep (9 feet). The responses of 

 the three species to the various orifice conditions are analyzed. More migrants 

 passed through shallow orifices than deep orifices, and more salmonids entered 

 vertical orifices than horizontal orifices. 



INTRODUCTION 



The position and type of entrance used to 

 attract migrating fish into fishways can be 

 important factors in expediting the movement 

 of fish at dams. A key part of fish-facility 

 complexes at most hydro- electric plants on 

 the Columbia River is the powerhouse fish- 

 collection system, a long channel extending 

 across the face of the powerhouse and con- 

 taining a number of entrances for fish. This 

 channel is one of several routes to the main 

 fishways. To enter the powerhouse collection 

 channel, however, migrants attracted by the 

 turbine discharge must locate entrance ports 

 above the turbine draft tubes. Large dis- 

 charges from fishway entrances also attract 

 numerous migrants directly to the entrances 

 of the main fish ladders. 



Fish-collection systems have been studied 

 by the Corps of Engineers to determine the 

 design criteria that would provide optimunn 

 entry conditions for upstream migrants. 

 Experiments at Bonneville Dam indicated that 

 salmonids will enter the powerhouse collec- 

 tion system more readily through a sub- 

 merged orifice than over an overfall weir 

 entrance (U.S. Corps of Engineers, 1948). 

 Studies in 1952 and 1954 (U.S. Corps of Engi- 

 neers, 1960b) showed that shallow orifices 

 (those submerged 3.8 to 6 feet) were more 



effective as entrances for fish than inter- 

 mediate (14.8 feet) or deep orifices (30 feet). 

 Continued research in I960 indicated that more 

 fish used vertical orifices than horizontal 

 orifices (U.S. Corps of Engineers, 1960a), 

 but results were not conclusive. 



The purpose of this study was to compare 

 the response of adult salmonids to rectangular 

 orifices placed in a vertical wall and aligned 

 vertically or horizontally, at shallow or deep 

 settings. The work was done in the Fisheries- 

 Engineering Research Laboratory-'- at Bonne- 

 ville Dam from August 24 to September 20, 

 1962. 



MATERIALS AND METHODS 



Test facilities (fig. 1) were housed in the 

 laboratory where special orifices and fish- 

 ways could be operated under controlled 

 hydraulic conditions. Test fish entered the 

 laboratory from the Washington shore fish- 

 way, passed through experimental orifices 

 and associated transportation channels, and 

 returned to the main fishway on their own 



^ Research financed by the U.S. Army Corps of Engi- 

 neers as part of a broad program to provide design 

 criteria for more economical and efficient fish-passage 

 facilities at Corps' projects on the Columbia River. 



