surveys, we observed a high 



Density/lOOO' + 95% CI 

 200 

 175 

 150 

 125 

 100 



75 



50 



25 

 



80 

 70 

 60 

 50 

 40 

 30 

 20 

 10 

 



incidence of fungal infections 



rA" 



1QRQ 1000 1001 IQO.'t lOOfi 100ft 9000 9009 9004 



-fffc 



■-,-:■*■ 



During our 

 (saprolignia) in 

 brown trout. 



Unlike the 



Johnsrud section, 

 we have not 

 observed northern 

 pike in the Scotty 

 Brown Bridge 



section in samples 

 to date. Our 

 observations of the 

 clinical signs of 

 whirling disease 

 (cranial » * ; 



deformities) 

 increased from 

 2002 to 2004 

 (Results Part IV). 



Wales Creek 



Section 



In 2002, we 

 established a new 

 fish population 

 survey site (the 

 Wales Creek 



Section) in a middle reach of Blackfoot River between the North Fork Blackfoot River 

 and Nevada Creek (rm 60.0-66.2). This section of the Blackfoot River suffers from 

 impaired water quality (high levels of fine sediment, summer water temperatures, and 

 nutrient levels) and degraded tributaries, all of which limit juvenile trout production and 

 recruitment to this reach of the Blackfoot River (Pierce et al. 2001 ; 2004). 



In May 2004, trout species composition (% of total catch for fish >6.0") in the 

 Wales Creek section was 84.8% brown frout (n=I51), 5.6 % WSCT (n=10) and 1.7 % 

 bull trout (n=3). We sampled no rainbow trout >6.0" in the Wales Creek section in 2004 

 compared with 14 in 2002. We estimated total trout density (> 6.0") for the Wales Creek 

 section at 9.1 fish /1 000' in 2004 compared to 12.7 in 2002, a decline of 28%. Of the 

 total trout estimate, the brown frout (> 6.0") point estimate was 8.6 fish/1000'. We did 

 not attain density estimates for the other species due to small sample sizes. The total 

 frout density estimate (>6.0") in the Wales Creek Section was only 19 % of the total 

 estimate in the Scotty Brown Bridge section, which is the nearest downstream main stem 

 survey section. 



' . ■ ' , 'Ti-' " , ■'■;\'. 



1989 1990 1991 1993 1996 1998 2000 2002 2004 



Figure 12. Densities of rainbow trout (> 6.0") in the Johnsrud (top) and 

 Scotty Brown (bottom) sections of the Blackfoot River, 1989-2004. 



24 



