WCT Multi-state Assessment February 10, 2003 



Table 5. Ranks and descriptions for disease risks to designated conservation populations of 

 westslope cutthroat trout in 2002. 



Rank Disease Risk 



1 Significant diseases and the pathogens that cause these diseases have very limited 

 opportunity to interact with existing WCT population. Significant disease and pathogens 

 are not known to exist in stream or watershed associated with WCT population. 



2 Significant diseases and/or pathogens have been introduced and/or identified in stream 

 and/or drainage further than 1 km from WCT population, but not in same stream 

 segment as WCT, or w ithin 1 km where existing barriers exist, but may be at risk of 

 failure. 



3 Significant diseases and/or pathogens have been introduced and/or have been identified 

 in same stream and/or drainage within 10km of WCT population and no barriers exist 

 between disease and/or pathogens and diseased fish species and WCT population. 



4 Significant disease and/or pathogens and disease carrying species are sympatric with 

 WCT in same stream segment. 



5 WCT population is known to be positive for significant disease and/or pathogens are 

 present. WCT population has a history of impacts from significant disease. 

 Environmental and/or biological condition may have intensified disease effects. 



Population Risks 



Demographic and stochastic population risks were assessed using criteria established by Rieman 

 et al. (1993). Four separate types of risk were considered including: temporal variability, 

 population size, population productivity, and isolation (Table 6). These four main factors were 

 assessed individually and then weighted and summed to derive a final composite risk factor. 

 Weightings were assigned to each risk factor based on advice from those who developed the 

 demographic and stochastic population risk matrix (Rieman et al. 1993; D. Lee, U.S.D.A. Forest 

 Service. Rocky Mountain Research Station. Boise, Idaho, personal communication) as: 

 Temporal Variability = 0.7; Population Size = 1.2; Population Productivity (Growth/Survival) = 

 1.6; and Isolation = 0.5. Weighted composite risk scores could potentially range from 4 to 16 

 and were then ranked into four low to high risk categories by placing them in four nearly equal- 

 sized bins (4 to < 7; 7 to < 10; 10 to <13; and 13 to 16). 



Conservation Activities 



A listing of potential conservation activities was provided to workshop participants. If any 

 conservation activity had been applied to any portion of a conservation population, that activity 

 was checked and linked to the conservation population (Table 7; Appendix B). Since we did not 

 specifically ask how many miles of habitat that was occupied by a conservation population was 

 also influenced by each type of activity, we summarized these data only by the number of 

 conservation populations affected by each conservation activity. For many conservation 

 populations, especially those that occupied larger areas of habitat, conservation activities only 

 affected a portion of the population. 



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