^ WCT Multi-state Assessment February 1 0, 2003 



To provide insight into the Hkely genetic status of WCT within habitats classified as "Suspected 

 Unaltered" and "Potentially Altered", especially in central Idaho where limited genetic testing 

 has been conducted, we took a closer look at classification results for 17 4th code HUC"s (Figure 

 5). For the ten HUC's that had stream reaches where some genetic testing was conducted we 

 compared the level of introgression within tested stream segments to the classifications for 

 stream segments where no genetic testing had been done (Table 10). Seven of these ten HUC's 

 had the majority of the stream segments classified as "Potentially Altered". Of these seven, 

 genetic testing in five HUC's found no evidence of introgression (HUC's 17010303, 17060303, 

 17060305, 17060307, 17060308; Table 10), while genetic testing in one HUC found 65% of 

 tested stream length had no evidence of introgression and testing in another HUC found evidence 

 of introgression in all tested samples. Conversely, some stream segments that supported WCT 

 classed as being "Suspected Unaltered" have probably been introgressed (e.g. HUC 17060206; 

 Table 10). although genetic testing found no evidence of introgression in the other two HUC's 

 that were predominated by streams classified as "Suspected Unaltered". The potential for 

 introgression is highest in stream segments that are connected to waters that support normative 

 species or subspecies that could potentially interbreed with WCT. 



Abundance Relative to Habitat Potential 



A total of almost 9,700 miles of historically occupied habitats (29% of currently occupied 

 habitats) supported populations believed to be at or near the habitat's potential capacity and over 

 9,300 miles of habitat (28% of occupied) supported populations significantly below potential 

 (Table 11). Of the nearly 9,700 miles of habitat that had populations deemed at or near habitat 

 capacity a total of about 1.190 miles (12% of miles deemed near capacity and 3% of occupied 

 habitats) also had no evidence of genetic introgression based on genetic testing. Over 30% of 

 habitats classified by abundance class had field estimates (high data quality) to support the 

 classification, while 47% had low data quality indicating professional judgment was used (Table 

 12). Over 40% of the length of those steam segments that were classified as "At or Near 

 Capacity" had field data to support that classification, while almost 40% were based on 

 professional judgment. 



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