capture site and was most often (80%) aquatic vegetation. 

 Aquatic vegetation and soil clumps were used in higher proportion 

 than they occurred, while pools were used in lower proportion 

 than they occurred. Substrate at microhabitat sites was 

 'cleaner' (less silt) and of larger particle size than was 

 available in the larger (adjacent) macrohabitat units. 



The three electrof ishing methods produced differences in 

 locations where YOY grayling were collected relative to upstream 

 or downstream riffles within microhabitat areas. The fish 

 collected while moving in an upstream direction with the backpack 

 electrof ishing unit were closer to the upstream riffle than fish 

 collected with either of the other two methods. The same type of 

 relationship was true for the fish collected while moving 

 downstream, in that they were collected closer to the downstream 

 riffle, while the fish collected in the grids were intermediate 

 in distance between the two riffles. This suggests that the two 

 methods requiring the samplers to enter and move about in the 

 water may displace the fish from their selected habitats and that 

 the fish collected with the grid method probably provide the most 

 reliable data with respect to microhabitat utilization. This 

 result also indicates the results presented by Skaar (1989) may 

 be biased and need to be re-examined. 



Age I and older grayling in the Big Hole River appear to 

 select a higher proportion of surface food items than do brook 

 trout in the same areas. Stomach content analyses showed very 

 little dietary overlap between the two species which indicates 

 there may be little competition for food between the two species 

 during the summer months. There were no YOY grayling found in 

 the stomach samples from brook trout, however, few stomach 

 samples were obtained early in the study when grayling fry had 

 recently emerged and would be most vulnerable. 



Young-of-the-year Arctic grayling showed a high fidelity for 

 specific riffle-pool-riffle complexes. The proximity of YOY 

 grayling to known spawning areas, as well as the lack of movement 

 for the majority of recaptured YOY grayling suggests that these 



