Com m on Na me 



Su sceptibility 



Table 16. Susceptibility to whirling disease among 

 species of salmonids in the Blackfoot River. Scale of 

 to 3 or S: = resistant; 1= partial resistance; 2 = 

 susceptible; 3 = highly susceptible; S = susceptibility 

 is unclear (conflicting reports), (adapted from 

 MacConnell and Vincent 2002). 



tributaries at several sites. For 

 example lower Cottonwood Creek, 

 highly infected since 1998, shows a 

 large decline in rainbow trout (mile 

 0.1) compared with the 1989 pre- 

 whirling disease period, whereas 

 brown trout densities have 

 dramatically increased (Figure 57). 

 A similar pattern was also observed 

 with YOY in this same section in 

 Cottonwood Creek. Likewise, brook 

 trout, a species susceptible to the 

 disease, have declined in one section 

 of Kleinschmidt in the presence of 

 high infection (Figure 58). 



Blackfoot River native 

 WSCT and bull trout appear to have 



a diminished risk of contracting whirling disease due in part to habitat use and life history 

 strategies that entail spawning and rearing in tributaries, above the general elevation of 

 the disease. Whirling disease severity typically increases in the downstream direction in 

 Blackfoot River tributaries. This 

 inverse relationship between 

 elevation and infection has been 

 detected in previous studies (Hiner 

 and Moffitt 2001; Sandell 2001; 

 Smith 2001; Hubert 2002; Anderson 

 2004), and may be a result of the 

 parasite's lack of time in the area, 

 low numbers of myxospores in the 

 environment, or a lack of suitable 

 habitat supporting T. tubifex. 



In Cottonwood Creek, Smith 

 (1998) reported higher gradient, 

 higher elevation habitats typically 

 support lower T. tubifex densities 

 and thus fewer TAMs. Sentinel cage 

 studies confirm this relationship in 

 Cottonwood Creek where periodic 

 sampling reports high infections 

 near the mouth, but negative results 

 in the upper drainage (Pierce et al 

 2002; Table 14). Environmental 

 conditions (water temperature, 

 substrate and charmel type) similar 



to upper Cottonwood Creek occur in "^'8"'''' 58. CPUE for YOY on Kleinschmidt Spring 



Creek, 1998-2003. 



iill 



Figure 57. CPUE in Cottonwood Creek for rainbow and 

 brown trout. 



94 



