ABSTRACT 



This work is a compilation and extension of previous studies 

 to quantify flow requirements, define fish life history and assess 

 the impacts of energy development on the aquatic resource of the 

 lower Yellowstone River and its tributaries. 



Chronology of abundance of sauger, tag returns, and 

 distribution of eggs and lairvae show that the Tongue and Powder 

 rivers are important spawning areas for this species in the 

 Yellowstone River system. Little evidence was found of mainstem 

 reproduction indicating that if these two tributaries are lost as 

 spawning grounds sauger could be severely reduced in numbers in the 

 Yellowstone River system. It was observed that 300 cfs was the 

 critical low flow for sauger reproduction in the Tongue River. The 

 allocated instream flow for the Tongue River is 75 cfs or 25 

 percent of the critical low flow. Water temperatures at peak 

 sauger spawning ranged from 13 to 14°C. 



Fifteen spawning areas for walleye were located in the 

 Yellowstone from just upstream from Glendive (river km 163) to the 

 North Dakota border (river km 18) . The largest and most important 

 of these spawning areas occurs just downstream from Intake 

 diversion. The spawning population at this site in 1978 was 

 estimated to be 991 walleye per kilometer. Favorable spawning 

 flows at the Intake gravel bar were predicted to range between 

 6,000 to 11,000 cfs. Walleye chose to spawn over a pebble or 

 cobble substrate, in water velocities of 43-96 cm/s, and a minimum 

 depth of 30 cm. Few walleye spawning areas were found downstream 



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