YCT Multi-state Assessment 



February 10,2003 



25 



Genetic Sample Size 



n< = 1% introgression 

 !■> 1% introgression 



10 15 20 25 30 



Number of Fish in Each Sample 



45 



Figure 4. Distribution of the number offish sampled for genetic testing, by level of introgression 

 detected, for assessment done in 2001. 



Abundance Relative to Habitat Potential 



A total of almost 2,281 miles of occupied habitats (30% of currently occupied habitats) 

 supported populations identified as being abundant (i.e. believed to be at or near the habitat's 

 potential capacity); over 3,302 miles of occupied habitat had population levels viewed as 

 common (44% of occupied); about 1,505 miles of occupied habitat supported populations 

 considered as rare (i.e. could be linked to habitat significantly below potential); and, 439 miles of 

 occupied had unknown population abundance (Table 8). Of nearly 2,281 miles of habitat that 

 had populations deemed to be abundant, a total of about 465 miles (20% of miles deemed near 

 capacity and 6% of occupied habitats) also had no evidence of genetic introgression. Over 81% 

 of habitats classified as abundant had field estimates to support the classification, while only 3% 

 had data that identified professional judgment as an information source (Table 9). 

 Approximately 525 miles of occupied habitat (40%) with abundance classified as common was 

 associated with genetically unaltered YCT. Only 288 miles of occupied habitat (22%) 

 supporting genetically unaltered YCT had population levels rated as rare. 



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