Cascade Reservoir, Idaho, to determine how 

 to control the extremely large popxilation there. 

 He found that: 



•Squawfish migrated from the reservoir 

 into two of the larger tributaries to spawn 

 (North Fork of the Payette River and Lake 

 Fork Creek). 

 •No evidence of spawning existed in Cas- 

 cade Reservoir proper. 

 •Squawfish spawned in the two tributaries 

 in late June and early July; after spawn- 

 ing, the fish returned to the reservoir 

 immediately. 

 •Squawfish fry drifted gradually from the 

 spawning stream to the backwaters of the 

 reservoir throughout the summer and fall. 

 •Control of squawfish in Cascade Reservoir 

 appeared possible by trapping or treating 

 them with rotenone while they were con- 

 centrated during the spawning run. 

 Hasselman and Garrison'' found that the 

 squawfish of Lookout Point Reservoir on the 

 Middle Fork of the Willamette River, Greg., 

 migrated to the upper end of the reservoir to 

 spawn. The authors reported that four small 

 tributaries which empty into the reservoir are 

 probably too snnall to provide areas with re- 

 quirements for large concentrations of spawn- 

 ing squawfish. 



In 1953-57 the Bureau of Commercial Fish- 

 eries Biological Laboratory, Seattle, Wash., 

 studied in the laboratory the use of electricity 

 to control northern squawfish. This research 

 was directed toward (1) preventing adult 

 squawfish from moving into the areas where 

 hatchery-reared salmon fingerlings were re- 

 leased, so that the yovmg salmon could safely 

 disperse,^ and (2) catching adult squawfish by 

 using sequentially pulsed d.c. fields to lead 

 them into enclosures or traps (Maxfield, 

 Liscom, and Lander, 1959). 



In the spring of 1958, the Bureau and the 

 Idaho Department of Fish and Game agreed to 

 install an experimental electrical structure 

 (electrode array and appurtenances) at Cascade 

 Reservoir and to estimate the structure's ef- 

 fectiveness in diverting northern squawfish 

 into traps. 



EXPERIMENTAL SITE AND INSTALLATION 



Cascade Reservoir (fig. 1) is 1,473 m. above 

 sea level in Valley County, Idaho. When full, 

 it is about 42 km. long and covers 14,528 ha. 



Hasselman, Ronald, and Robert Garrison. 1957. Stud- 

 ies on the squawfish, Ptychochellus oregonense. In Look- 

 out Point and Dexter reservoirs, 1957. Joint research 

 study, U.S. Fish Wlldl. Serv., Portland, and Dep. Fish 

 Game Manage., Oreg. State Coll., Corvallls, 41 pp. 

 [Processed.] 



^Maxfield, Galen H., and C. D. Volz. An electrical 

 barrier for controlling squawfish (Ptychochellus orego- 

 nesls) predatlon. Bur. Comm. Fish., Biol. Lab., Seattle, 

 Wash. [Unpublished manuscript, 41 pp.] 



The experimental site for the electrical in- 

 stallation was at the North Fork bridge that 

 crosses the reservoir (at what was formerly 

 Tamarack Falls) on the North Fork of the 

 Payette River. Here the reservoir is con- 

 stricted to a 31 -m. -wide channel by the two 

 concrete abutments of the bridge; depth at 

 peak level ranges from about 3 m. at the 

 abutments to 5 m. at midstream. The reservoir 

 at peak level widens considerably on the up- 

 stream side of the bridge and to a lesser 

 degree on the immediate downstream side. 



The experimental installation consisted of 

 (1) a V-shaped electrode array in the center 

 of the stream and (2) two nonelectrified traps 

 at the water's edge--one at each end of the 

 electrode array. The installation and its oper- 

 ation are described in five sections: (1) elec- 

 trode array and traps, (2) power source, 

 (3) electronic equipment, (4) method of ener- 

 gizing array, and (5) electrical conditions. 



Electrode Array and Traps 



The V-shaped electrode array, with apex 

 downstream, consisted of three parallel rows 

 of vertical electrodes (2.6-cm. thin-wall elec- 

 trical conduit) spaced 0.6 m. apart in each 

 row (figure 2). The downstream and middle 

 rows of electrodes were 1.5 m. apart, and the 

 middle and upstream rows were 0.6 m. apart. 



We assembled the electrodes in sections, 

 which consisted of either two or four elec- 

 trodes inserted at 0.6-m. intervals in an upper 

 and a lower 5.1- by 10.2-cm. "spacer" board, 

 which maintained the correct spacing of the 

 electrodes during and after installation. The 

 lower spacer (fig. 3) was about 1.2 m. from the 

 lower ends of the electrodes. The upper spacer 

 boards were mounted on a floating support 

 structure that was not secured to the elec- 

 trodes; therefore, the support structure moved 

 freely up and down the electrodes when the 

 water level changed. The lower ends of the 

 vertical electrodes, the lengths of which were 

 from 3.7 to 6.1 m. depending upon the water 

 depth, were embedded in the stream bottom. 



The support structure for the electrode array 

 was built by joining balsa wood liferafts with 

 planks, or stringers, in two sections that were 

 floated into position and joined in a V-shape 

 (fig. 2). The structure was held in position by 

 a vertical 10.2- by 30.6-cm. plank secured to 

 the bridge at each wing of the Vin such a man- 

 ner that it was free to rise and fall with change 

 in water level. The apex of the support struc- 

 ture was 21.3 m. downstream from thebridge; 

 the length of each arm of the V-shaped elec- 

 trode array was 20.7 m. 



A 4.6- by 6.1-m. rectangular screen of gal- 

 vanized hardware cloth (4 meshes per 2.5 cm.), 

 mounted on a frame of 2.5-cm. galvanized 

 pipe, was positioned in the water from each 

 upstream end of the electrode array to the 

 closest trap lead. The two screens (fig. 2) 



