system (Table 2). The majority of walleye were mature; 68, 13, and 

 19 percent were males, females and immature, respectively. Walleye 

 never exceeded 4 percent of the combined catch of mature walleye 

 and sauger in the Tongue or Powder rivers during spring. 



During the spring of 1980, one side of the Yellowstone River 

 was electrof ished from Miles City to the North Dakota border (272 

 river km) . Walleye were first captured consistently beginning at 

 section 11 downstream from Terry, Montana (river km 222) while 78 

 percent of all mature walleye were captured in the reach from 

 Intake diversion to the North Dakota border (Figure 21) . The 

 greatest number of walleye were captured in section 24, immediately 

 downstream from Intake only during spring. Walleye comprised 73 

 percent of the combined catch (420 fish) of all mature walleye and 

 sauger captured on this electrof ishing run (Table 12) . Considering 

 the Yellowstone River as a whole, sauger are much more abundant 

 than walleye. 



During any one year walleye comprised 50 to 89 percent of the 

 total number of mature walleye and sauger caught downstream from 

 Intake diversion dam during March - May 1976-1980. Walleye 

 averaged 76 percent of the catch for all 5 years (Table 13) . 

 Female walleye averaged 48 percent of the combined catch of female 

 sauger and walleye sampled while male walleye averaged 79 percent 

 of the catch of males for the two species. Walleye used the gravel 

 bar downstream from Intake extensively for spawning, while sauger, 

 although at times abundant, tended to spawn at other locations (see 



65 



