Table 5. Frequency of cover types within a 3.28 square foot area 

 centered where young-of-the-year Arctic grayling were 

 captured with electrof ishing grids and of cover types 

 within the larger macrohabitat areas on the Big Hole 

 River. 



Capture Sites (%) Macrohabitat (%) 

 Cover Type (Use) (Availability) 



Aquatic Vegetation 8 7 5 



Pool 11 19 



Soil Clump 4 1 



Debris 1 2 



Terrestrial Veg. 1 1 



Bank 2 1 



Substrate 



Silt comprised 27.86% of the substrate materials in the 

 macrohabitat areas and only 8.33% in grid-capture sites (Table 4). 

 Embeddedness was lower and the percent substrate composition made up 

 by larger particles (large gravel and cobble) was higher at grid- 

 capture sites than in the adjacent macrohabitat areas, indicating a 

 possible preference for clean substrate with larger particles. 



Temperature 



Stream temperatures were only randomly recorded and were not 

 always taken when the water temperature was at its daily maximum, 

 therefore the data in Table 6 are presented only to provide a very 

 general thermal trend through time. The highest maximum daily water 

 temperatures occurred from the end of July through the first week of 

 August and appear to be lower, in general, than temperatures recorded 

 in the same area in 1988 (Skaar 1989) . No thermally induced mortality 

 was observed. 



29 



