The backpack system was used primarily in side channels, 

 irrigation ditches and smaller tributaries of the Big Hole River 

 where flows seldom exceeded 15 CFS. Backpack electrof ishing 

 proceeded in an upstream direction when data were collected for 

 distribution and relative abundance. Electrof ishing proceeded 

 both upstream and downstream while marking locations for later 

 microhabitat measurements. Samplers would move as quietly as 

 possible and stab the electrode in the water in an attempt to 

 avoid displacing the YOY grayling. We immediately marked 

 locations where specimens were captured for later habitat 

 measurements. Different colored rocks were used to differentiate 

 between sites where fish were captured: 1) while backpack 

 shocking upstream, 2) while backpack shocking downstream, or 3) 

 in a grid apparatus. The grid system was used in areas where we 

 had captured large numbers of YOY grayling to try to determine 

 whether the fish captured with each backpacking system had been 

 displaced. The six grids, ranging from three to 12 square feet 

 in size, were typically set in appropriate habitat from 12 to 72 

 hours before the power supply was turned on. A netter was 

 positioned downstream of the grid (often on the streambank) and 

 remained motionless for 3 seconds to two minutes until the 

 person operating the power supply (either in the boat downstream 

 or on the bank) about 50 feet away supplied power to the grid. 

 The netter then rushed forward and netted the fish as they were 

 stunned in the area inside the grid. If YOY grayling were 

 captured, then each spot was immediately marked with one of the 

 aforementioned colored rocks for later microhabitat measurements. 

 In addition to Arctic grayling and brook trout, YOY mountain 

 whitefish ( Prosopium williamsoni ) and rainbow trout (Oncorhynchus 

 mykiss ) were netted and placed in a live car until they were 

 measured to the nearest 0.1 inch in total length (TL) and weighed 

 to the nearest 0.01 pound. Lengths and weights were converted to 

 metric units and condition factors (K) were calculated using the 

 following equation: 



