Flow 



d left < Vletc 



spawning area (Rosgen 2002). At the spawning site scale, we measured: 1) individual 

 redds; 2) spawning substrates; 3) discharge; and 4) placed thermographs for continuous 

 winter temperature monitoring as described below. All field surveys were completed in 

 October 2004 following the bull trout-spawning period. 



To characterize spawning substrates, we extracted 33 McNeil core samples (range 

 6-12 per stream) from spawning areas using modified methods of McNeil and Ahnell 

 (1964). Core samples were collected immediately adjacent (within 18 inches) to the 

 center of the redd. For streams with fewer than six redds, cores were taken adjacent to 

 redds where possible and at comparable sites deemed suitable to spawning. Extracted 

 core samples were sent to the Helena National Forest Hydrology Lab in Helena for 

 sieving and lab analysis. Streambed samples were oven dried and shaken through sieve 

 series containing 76.2 50.8, 25.4, 12.7 6.3 4.76 2.38, 0.85, 0.074 mm mesh screens. The 

 material retained within each sieve and the pan was weighed to the nearest hundredth of a 

 gram. The estimated dry weight of the sediment within the Imhoff cone (a measure of 

 the suspended sediment) was added to the weight of material <0.074. Stream 

 compositions were reported as a percentage of each size class by weight. Lab 

 calculations also included 1) measures of central tendency ("Fredle" index and geometric 

 means) to classify substrate quality in terms of reproductive potential of spawning gravel, 

 and 2) quantification of "percent fines" (<0.84mm and <6.35mm) within each of the 

 spawning areas. Survival of emergent bull trout fiy was also estimated from the 

 equation: y = -1.29462x (% 

 fines<6.35) +72.4615 (R^- 

 0.91, p=<0.05) (Fraley and 

 Weaver 1991). 



To further 



characterize the properties of 

 redds, we measured 37 

 individual bull trout redds 

 (Copper Creek (n=14), 

 Dunham Creek (n=3). Gold 

 Creek (n=6) and Monture 

 Creek (n=14)). Seven 



measurements were taken at 

 each redd, including 

 velocities and depths at 5 

 locations (Vup, Vpit, Vtail, 

 dleft and dright) and lengths 

 (tail and pit) at two sites 

 (Figure 54). We selected 

 only redds that displayed a 

 definite pit and tailspill and 

 avoided areas of superimposition. All velocity measurements were taken with Marsh- 

 McBimey model 2000 flow meter at 0.6 times the water column depth. We measured 

 depths with the top-setting rod and lengths with a tape. Similar to Schmetterling (1999), 

 redd pit lengths were measured fi"om the upstream edge of the pit to the upstream edge of 

 the tailspill. Similarly, tailspill lengths were measured from the upstream end of the 



dcighc « V eight 



70 



