supporting permanent perennial grasses and sedges. Mean depth and 

 velocity for the macrohabitat areas were 0.83 ft and 0.29 ft/s, 

 respectively. These mean depths and velocities are slightly less than 

 the means for these parameters measured at the capture sites. 



Microhabitat Utilization 



Depth and Velocity 



Habitat preference is exhibited when fish utilize a particular 

 habitat variable with greater frequency than it is available (Bovee 

 1986) . Young-of-the-year Arctic grayling utilized deeper areas of the 

 Big Hole River with a frequency slightly higher than availability 

 (Figs. 8 and 9). They also selected higher velocity areas (Figs. 10 

 and 11). Availability was determined by measuring at 1,311 points 

 along transects in macrohabitat areas. Since these areas may have 

 been of higher quality and of different composition than in unused 

 surrounding macrohabitat areas, these determinations of preference may 

 be inaccurate. Random sections of stream were not measured to develop 

 a true index of availability. 



Cover 



The average distance from a capture site to the nearest cover for 

 grid-captured YOY grayling was 1.02 ft. Aquatic vegetation was the 

 cover type closest to 80% of these sites (Tables 4 and 5) . Skaar 

 (1989) reported similar findings for these measures of 0.92 ft and 

 86%, respectively. Rannunculus aquatilis and Elodea canadensis were 

 the primary species of aquatic vegetation (Skaar 1989) . Other cover 

 frequencies were also similar to those reported for the same area in 

 1988 by Skaar (1989) . Aquatic vegetation and soil clumps were 

 utilized in slightly higher proportion than they occurred, while pools 

 were utilized in slightly lower proportion than they occurred. 

 Debris, terrestrial vegetation, and banks were used in approximate 

 proportion to their occurrence. 



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