materials suspended. The minimum water velocity where any one egg 

 would be expected to occur on the Intake gravel bar (90% level of 

 confidence) was 45 and 43 cm/s during 1978 and 1979, respectively 

 (Table 21) . These velocities are probably close to the minimum 

 current velocities necessary to keep the gravel washed and free of 

 silt. 



The mean weighted velocity of sites where eggs were collected 

 was 84, 70, and 71 cm/s in 1977, 1978 and 1979, respectively. The 

 range of velocities in which eggs were collected was narrower in 

 1977 than the other two years (Figure 26) . The velocities at sites 

 sampled all 3 years ranged from to 120.7 cm/s while the range of 

 velocities at sites where eggs were collected ranged from 25.5 to 

 107.9 cm/s. 



All eggs, each of three years, were collected over a cobble or 



pebble substrate. No eggs were collected in substrate covered by 



or containing sand and silt. Various other workers reported that 



walleye and sauger select a cobble or pebble substrate (Nelson 



1968a, Rawson and Scholl 1978, Priegel 1969, Nelson and Walburg 



Table 21. Depth (cm) and velocity (cm/s) criteria for sites where 

 Stizostedion sp. eggs were collected on the Intake 



a,b 



Means with same superscript are significantly different at 

 p<.001. 



87 



