of both species in undisturbed areas, compared to the single species dom- 

 inance in the mined areas, again reflects the reduced habitat diversity in 

 areas disturbed by gravel removal. 



The Penny River pit provided coho salmon rearing habitat, which was lim- 

 ited in the river. Arctic char appeared to be more suited to the river 

 environment than coho salmon, and avoided the pit. The pit thus provided 

 ideal rearing conditions for coho with little competition from Arctic char. 

 There was a significant difference in size of coho using the pit as compared 

 to those using the river possibly indicating increased growth rate by those 

 in the pit (Tables 22 and 23). During the winter the coho left the pit and 

 moved to other areas where they possibly would be in direct competition with 

 char for space. If overwintering space is limiting in this river system, the 

 increased number of larger coho could lead to displacement and subsequent 

 reduction in the numbers of char. The Prospect Creek pit, a shallow pond 

 habitat previously not present in the immediate area, was used as a rearing 

 area by Arctic grayling, round whitefish, Chinook salmon, burbot, and slimy 

 sculpin, and also provided a feeding area for adult northern pike (Figure 

 55). In the upstream area of Prospect Creek the catch in 1977 was dominated 

 by round whitefish, Arctic grayling, and slimy sculpin listed in diminishing 

 order of abundance. In 1978 juvenile Chinook salmon appeared to dominate the 

 fish populations in the creek. 



The Dietrich R i ver-Upstream pit and associated channels provided a 

 deep-water, spring-fed system utilized principally by adult Arctic grayling 

 and Arctic char while the main river contained juvenile Arctic grayling, 

 slimy sculpin, and round whitefish. 



The West Fork Tolovana River pit contained extensive vegetated shallow 

 water areas which sloped off rapidly to deep water areas up to 6 m deep, 

 thus creating excellent spawning, rearing, and feeding areas for northern 

 pike and feeding areas for adult Arctic grayling (Figure 56). Arctic gray- 

 ling were the only species captured in the river during three sampling 

 trips, while northern pike were abundant in the pit. The only Arctic gray- 

 ling captured in the pit were adults longer than 225 mm; smaller Arctic 



185 



