conservative approach would be to manage this as a pure westslope cutthroat trout 

 population. 



iVasson Creek: (longitudinal sample) All 32 successfully amplified individuals in this 

 sample exhibited only fragments diagnostic of westslope cutthroat trout. With a sample 

 size of 32, we have a 92% chance of detecting as little as 1% hybridization between 

 westslope cutthroat trout and rainbow trout using four PINE markers. Although we 

 found no evidence of introgression, our confidence in our ability to detect hybridization 

 between westslope cutthroat trout and rainbow trout is lower than if we had been able to 

 analyze the sample at all si.x. rainbow marker loci. Until further data indicate otherwise, 

 the conservative approach would be to manage this as a pure westslope cutthroat trout 

 population. 



Union Creek: (longitudinal sample) All 16 successfully amplified individuals in this 

 sample exhibited fragments diagnostic of westslope cutthroat trout. Individuals from two 

 of the three sampling sites (S2 and S4) contained hybrid individuals. The single 

 individual from S3 failed to amplify. Assuming random mating proportions, the genetic 

 contribution of westslope cutthroat trout and rainbow trout is 92% and 8%), respectively. 



Pattee Creek: All 10 individuals in this sample exhibited only fragments diagnostic of 

 westslope cutthroat trout. With a sample size of 10, we have only a 70% chance of 

 detecting as little as 1% hybridization between westslope cutthroat trout and rainbow 

 trout using six PINE markers. Although we found no evidence of introgression. our 

 confidence in our ability to detect introgression with rainbow trout is lower than if we 

 had a full sample to analyze. Until further data indicate otherwise, the conservative 

 approach would be to manage this as a pure westslope cutthroat trout population. 



Sincerely, 



Marirose Spade 



Cc: Steve Carson (email) 



