I 



Figure 3. — Cross section of a main unit (turbine and as- 

 sociate<l water passages) at The Dalles Dam with in- 

 take frame in fishing position. 



in place were almost the same throughout the zone 

 strained by the nets, except for tlie normal bound- 

 ary layer associated with the intake ceiling.^ 

 Therefore, all nets strained about the same amount 

 of water. 



The uppermost net was placed on the frame so 

 the top edge of the net moutli was aligned witli the 

 intake ceiling. The frame used at The Dalles Dam 

 was equipped with a stationary fish-tight screen 

 extending from the top edge of the net mouth to the 

 upstream side of the fi'ame to provide a partial 

 block of the opening to the gatewell (fig. 5). At 

 McNary Dam, the frame was equipped with 

 a hinged screen as well as a stationary screen (fig. 

 5). Together, the screens formed a fish-tight bar- 

 rier that blocked the entire opening to the giite- 

 well upstream from the toj) net. 



The nets at both Dams were 1.97 m. wide by 2.18 

 m. high at the mouth and were 5.79 m. long, includ- 



ing the cod end. Fyke nets at The Dalles Dam in- 

 corporated 12.7 mm. stretched mesh nylon webbing 

 in the forward half of tlie body and 9.5 nmi. 

 stretched mesh nylon in the back half. At The 

 Dalles, the smaller mesh tended to plug up with 

 line vegetable debris; tJic difliculty was alleviated 

 at McNary Dam by constructing fyke nets en- 

 tirely of 12.7 mm. stretched mesh. Cod ends of the 

 nets at both Dams were of 3.2 mm. nylon bobbinet. 

 Procedure was the same at both Dams. Before 

 the frame was lowered to fishing position, each 

 net was folded and tied to the frame with string 

 that could be broken easily by flows in the turbine 

 intake. Flows were stopped before the frame was 

 lowered or raised to prevent capture of fish while 

 the nets were moving up or down. At the end of 

 each fishing period, the intake frame was hauled 

 to deck level, and the contents of each net were 

 emptied into separate containers for sorting and 

 counting. 



' Cnpubllslicd data furnished by U.S. Army Corps of Engineers, 

 North Pacific Division, Water Control Branch, 921 SW. Washing- 

 ton, Portland, Greg. 97205. 



KlouRF. 4. — Intake frame being lowered through gatewell 

 into a turbine intake at MeXary Dam. Frame .-supports 

 fyke nets used to measure diel movement and vertical 

 distribution of tingerling salmonids approaching 

 Kaplan turbines. 



602 



U.S. FISH AND WILDLIFE SERVICE 



