CONCLUSIONS 



This study attempted to identify several possible factors that 

 may be limiting the Big Hole River population of Arctic grayling. 

 Based on stomach contents collected in this study, we have found 

 that while brook trout can and will prey upon YOY grayling, the 

 amount of predation actually occurring on YOY is probably not 

 limiting the grayling population. In addition, substrate composi- 

 tion does not appear to be highly correlated with YOY numbers, 

 although several study design problems were discussed. The use of 

 irrigation ditches by grayling appears to be minimal except in one 

 case discussed. If grayling do leave the ditch in the fall, then 

 the adverse impact on them would be negligible and no further steps 

 other than monitoring need be taken. Data collected on the 

 movements of YOY in the river section below the Wisdom cemetery is 

 circumstantial due primarily to the low numbers of YOY marked. The 

 data, however, may indicate that the YOY move downstream. 



The proposed stocking of the river with hatchery-reared 

 grayling, and continued studies such as this one, as well as those 

 of McMichael (1989) and Skaar (1988), are vital in not only main- 

 taining and increasing Arctic grayling populations in the Big Hole 

 River drainage, but also in determining the causes for their 

 decline. Until these causes are identified, and corrective 

 measures result in substantial increases in grayling numbers, the 

 grayling population in the Big Hole River should remain of special 

 concern. 



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