currently being pursued by FWP and University of Montana. 



Blackfoot River native WSCT and bull trout appear to have a diminished risk of 

 contracting whirling disease due to habitat use and life history strategies that entail 

 spawning and rearing in tributaries, above the general elevation of highly infected waters. 

 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 (Smith 1998; Hiner and Moffitt 2001; Sandell 2001; Hubert 

 2002; Anderson 2004), and may be a result of the parasite's recent introduction 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. Periodic 

 sentinel cage samplings confirm high infections near the mouth but negative results in the 

 upper drainage in support of this relationship (Pierce et al 2002). "Headwater" conditions 

 (water temperature, substrate and channel type) similar to upper Cottonwood Creek occur 

 in tributaries of the lower drainage (Gold, Belmont and Bear Creeks), and many other 

 tributaries to the Blackfoot River. Many of these streams show mild infection levels, 

 despite higher infections in nearby receiving waters. Water temperatures in basin-fed 

 streams are also typically much lower in forested and upper stream reaches (Pierce et al. 

 2002) and out of the reported critical temperature range of high-risk waters (Vincent 

 2002, FWP unpublished data). As a result, exposure risk appears to have a longitudinal 

 component. 



Downstream-infected areas often overlap with spawning and rearing areas 

 rainbow and brown trout, mountain whitefish and other species. Conversely, telemetry 

 studies of WSCT and bull trout show these native species generally reproduce upstream 

 of the disease, while occupying infected water at non- vulnerable (early) life-stages. One 

 notable exception however is lower Chamberlain Creek where concentrated WSCT 

 spawning and high juvenile densities in the lower stream overlap with a high whirling 

 disease infection. Infection levels in July have reached mean grades of 3.9, a grade 

 considered to cause population declines in exposed fish (Vincent 2002). At this time, 

 population monitoring suggests generally stable WSCT densities. 



In the Blackfoot watershed, the role of habitat restoration to fisheries in highly 

 infected streams is being investigated on many fi-onts. One objective is to determine if 

 restoring an infected system (i.e. reducing favorable worm habitat by regaining flushing 

 flows and reducing sediment input through stabilizing banks) will moderate the disease. 

 The premise behind this idea is a result of several ecological risk factors being 

 hypothesized to influence whirling disease severity. These factors include: high 

 productivity, lack of flushing flows, low gradient, human altered or enriched habitats that 

 amplify the density of T. tubifex, and the presence of brown trout that can act as a 

 reservoir for the disease (Modin 1998; McWilliams 1999; Zendt and Bergersen 2000). A 

 second objective is to relate infection levels to the longitudinal continuum of 

 morphological (and other physical) characteristics of channel-types (Vannote et al 1980; 

 Smith 1998; Rosgen 2002). The premise here relates to perceived regional relationships 

 of infections and potential opportunities for specific enhancement techniques associated 

 with predictable spatial changes in channel-types and salmonid species (and life-stages) 

 therein. The relationships of WD to channel-types and other biophysical attributes of 



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