species was similar between three study reaches where fish were captured (ANOVA, 

 WSCT P = 0.79; bull trout P = 0.81). Inter-annual differences on the mean start date of 

 migration were not different for WSCT (Mann- Whitney Rank Sum, P = 0.056). Size of 

 fish did not appear to effect distance of migration (Simple linear regression: WSCT: R^ = 

 0.01, P = 0.64; bull trout: R^ = 0.14, P = 0.29), or timing of the initial starting date of 

 migration (Simple linear regression, WSCT: R^ = 0.02, P = 0.50; Bull trout: R" = 0.05, P 

 = 0.52). However, a relationship was found between the date WSCT migration began 

 and the distance moved (pre-spawning movement) (Simple linear regression; R' = 0.21, P 

 = 0.01). The same relationship was not found with bull trout (Simple linear regression; 

 R = 0.35, P = 0.07). Although river temperatures were similar between 2002 and 2003 

 peak flows occurred approximately three weeks earlier in 2002 (Figure 47). WSCT 

 migrations began on the rising limb of the hydrograph, as temperatures approached 40''F. 

 Before ascending spawning streams, nineteen WSCT and five bull trout migrated 

 upstream, while nine WSCT and five bull trout moved downstream. The river migration 

 period for WSCT trout averaged 16.1 days (range 1-68); while bull trout averaged 44 

 days (range 8-109). The average number of river miles moved before ascending 

 tributaries varied from 13 miles (range 0.2-37.7) for WSCT trout, to 28 miles (range 3.3- 

 82.4) for bull trout. WSCT entered tributaries a mean (tributary) temperature of 44 °F 

 (range 33-53); whereas bull trout entered spawning streams at mean temperatures of 50.5 

 °F (range 43-62). Total river movement of non-migratory WSCT (n = 15) averaged 16.6 

 miles (range 0.1-34.4). 



WSCT spawning streams varied in size from 1^' to 4' order, while bull trout used 

 only 3"^ to 4' order tributaries. WSCT spawning occurred in seven tributaries (North 

 Fork of the Blackfoot River, Wales, Arrastra, Sauerkraut, Hogum, Copper, and upper 

 Willow Creeks with Arrastra Creek and upper Willow Creek supporting the highest 

 percentages of total spawning use nine spawners (34%) and five spawners (22%), 

 respecfively (Figure 48). Each had at least one spawner ft-om 2002 return in 2003. Bull 

 trout spawning was limited exclusively to North Fork of the Blackfoot River and Copper 

 Creek (Figure 49). WSCT entered tributaries between mid-April through mid-June 

 (median date: May 19), while bull trout entered tributaries between late May and late July 

 (median date: June 15). No significant differences were found when comparing the mean 

 date WSCT and bull trout entered individual tributaries (WSCT = ANOVA, P = 0.18; 

 Bull trout = Mann Whitney, P = 0.19). Average tributary movement was 5.7 miles for 

 WSCT trout (range 0.4-48.0) and 12.7 miles for bull trout (range 0.6-18.5). WSCT trout 

 averaged 51.5 days in tributaries (range 4-153); while bull trout stayed longer with an 

 average of 160 days (range 60-358). WSCT spent significantly different amounts of 

 time in the seven different spawning tributaries, staying in the largest tributary, the North 

 Fork, the longest (ANOVA, P = 0.002). We found a significant relationship between the 

 drainage area of individual spawning tributaries and the number of days WSCT remained 

 in these tributaries (Simple linear regression; R^ = 0.67, P = 0.04). When comparing the 

 number of days bull trout spent in the North Fork compared with Copper Creek, 

 significant differences were not detected (Mann- Whitney, P - 0.1 1). However, the mean 

 number of days bull trout spent in Copper Creek was 258, compared with 83.2 days in the 

 North Fork, a 3 1 % decrease. 



68 



