WCT Multi-state Assessment 



February 10,2003 



Management Impacts on Conservation Populations 



While it was difficult to definitively link land use impacts to specific portions of conservation 

 populations, at least some portion of habitats in over 50% of the conservation populations were 

 considered to have been impacted by land use activities such as timber harvest, livestock grazing, 

 or roads (Table 18). Angling and water withdrawals were identified as having known impacts to 

 about 1 5% of the populations. Mining was having known impacts to about 7% of the 

 populations. "Possible" impacts affected a higher number of conservation populations than those 

 that were "Known", and the proportions of conservation populations that were impacted by each 

 type of activity were similar for all activities except timber harvest and angling. 



Table 18. Number and percentage (based on the 539 conservation populations that were 



evaluated) of designated westslope cutthroat trout conservation populations where 

 human management activities were known or believed (possible) to have impacted the 

 population by type of management activity. 



Discussion and Conclusions 



Historical Range 



Although the historical habitats of WCT delineated by this assessment differ from previous 

 assessments (Hanzel 1959; Behnke 1979; Liknes 1984; Liknes and Graham 1988; Behnke 1992; 

 Van Eimeren 1996; Lee et al. 1997; Shepard et al. 1997; Thurow et al. 1997; U.S. Fish and 

 Wildlife Service 1999), our review provides the most comprehensive and current assessment of 

 historical range. Behnke (1979; 1992) included the headwater portions of a few 4"^ code HUC's 

 that we excluded (Milk Headwaters and Upper Musselshell); however, he based his inclusion of 

 the Musselshell system primarily on information compiled by Hanzel (1959) and the Milk 



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