The catch per gill-net set for walleye ranged from 0.1 to 0.7 from 1966 

 to 1969, increasing to 1.5 in 1972 and 2.5 in 1973. The highest catch was in 

 1975, 2.8 fish per net. Walleye increased in size from 1966 to 1971, then 

 stabilized from 1972 to 1976 at a level just below the 1969-70 averages (figure 

 33). Sauger were not taken in gill nets until 1973, when 0.6 fish per set were 

 taken, as compared to 1.4 and 1.0 fish per set taken in 1975 and 1976, respect- 

 ively. Sauger appear to be increasing and are showing up in angler's creels. 



800 -1 



700 - 



600 - 



E 

 .§500 



c 400 - 



300 - 



200 - 



100 



Average Length 

 Range 



. t" 



1966 68 



69 



1^ 

 70 



72 



73 



74 



~r~ 



75 



76 



Figure 33. Average length and length range of walleyes from gill- 

 net catches. Tongue River Reservoir, 1966-76. 



Si ze, Age, and Growth . The average length of trap-netted walleye has variec 

 only about 13 percent since 1972, although the average weight has varied by 

 25 percent (table 31). The presence of small fish in the sample indicates 

 walleyes are successfully spawning in the reservoir. 



Length-frequency distributions for walleye (1974-76) are shown in figure 

 34. The size interval of 575-624 mm was dominant in 1974, contributing 31.1 

 percent. In 1975, young fish with a peak length of 350 mm (300-400 mm) were 

 dominant, comprising 43.9 percent. This size group shifted 100 nm in 1976, with 

 a peak of 450 mm (range 400-600 im). Small fish were absent in 1976, suggesting 

 a weak year class entering the population. Scale samples taken during the 

 spawning season suggest that walleyes enter the run at age IV+. Reservoir 

 storage showed a poor pattern in 1972; maximum stage was reached during March, 

 and water levels dropped during April with a slight increase during May. Thus, 



98 



