FIGURE 34.-The biological field station at Prescott, Oreg., 

 houses biological and chemical laboratories plus two "wet" lab- 

 oratories. Each wet lab has twenty-two 50-gallon tanks that 

 can be individually supplied with heated or cooled water from 

 the Columbia River. 



of the fish, and temperature of the river water to which 

 the fish were acclimated. Slow death of juvenile salmon 

 from exposure to elevated temperatures over a long period 

 has been described by other scientists, but our research 

 is the first in which anadromous species of the Columbia 

 River have been tested in their natural environment. In 

 experiments at Prescott, about half the juvenile salmon held 

 at 77° F. died within 1 week. 



In other experiments, adult eulachon (Thaleichthys pa- 

 cificus) from the Columbia River (fig. 35) were fairly in- 

 tolerant to temperature increases and all died when the 

 temperature was inci'eased 11° F. Female eulachon failed 

 to deijosit eggs after the water temperature was increased 

 a mere 5° F. 



FIGURE 35.-Eulachon, or Columbia River smelt. 



Turbine Studies 



About half of the young salmon and trout (0-age and 

 yearlings) now migrating down the Columbia River find 

 relatively safe passage over the spillways of dams. The 

 other half pass through the turbines, where 10 percent or 

 more are injured or killed by the turbine blades. Most of 

 the low-head dams on the Columbia River have Kaplan blades 

 (fig. 36). Some of the survivors of turbine passage are 

 disoriented or temporarily stunned, which sometimes makes 

 them easy victims of predators. 



Part of the survivors exiting with the turbine discharge 

 are carried into comparatively slack water below nonover- 

 flow sections of the dam. As many as one-third of these 

 fish are eaten by herring gulls (Larus argentatus), northern 

 squawfish {Ptychocheilns oregonensis) , and other predators. 

 The survivors enter the main flows and move downstream 

 where velocities are too high for many of the predators. In 

 a few years, however, the reservoirs now under construction 



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