Species Indicators: The following descriptions correspond to the 4 species indicators listed on 

 the FWS Matrix of Diagnostic of Diagnostics/Pathways and Indicators for bull trout (USFWS 

 1998). Each species indicator for the existing condition are described and rated at the 

 subpopulation scale. The entire Rock Creek drainage is considered a single subpopulation, 

 except for the bull trout above the dam on the East Fork. The dam effectively isolates these fish 

 from the rest of Rock Creek. 



1) Subpopulation Size: There are no reliable population estimates for the entire Rock Creek 

 drainage. However, based on the distribution of adult fish throughout the drainage, and the 

 number and distribution of tributaries that support substantial amount of spawning activity, it is 

 felt that Rock Creek supports a sizable, self-sustaining population of bull trout. This indicator is 

 rated as functioning appropriately for the entire subpopulation. 



The Upper Willow Creek watershed (170102021 1) does provide some habitat for all life stages 

 of bull trout. However, the watershed contains limited rearing and adult habitat. Low numbers 

 of subadults were captured during surveys of Beaver Creek and the mainstem Upper Willow 

 Creek. While spawning has not been documented in this Upper Willow Creek watershed, high 

 numbers of young of the year were captured during surveys conducted on State Trust Land in 

 Bear Creek during May 2000. Adults from Rock Creek that were radio-tagged for telematry 

 studies were found to spend substantial amounts of time in the Upper Willow Creek watershed. 

 Subwatershed -03 supports most of the documented use by adults. 



2) Growth & Survival: Sufficient data has not been collected to determine a trend in populaUon 

 size for bull trout in Rock Creek. Sampling completed in the Hogback section of the mainstem 

 of Rock Creek over the last 15 years indicate that the populaiton may be declining. Redd survey 

 data has been collected on select reaches in several tributaries for up to seven years. However, it 

 is not sufficient to detect any sort of trend. Therefore, this indicator was rated as functioning at 

 risk. 



3) Life History Diversity & Isolation: The migratory form of bull trout is present in Rock Creek. 

 The adjacent subpopulations include those found in the Blackfoot River and the Upper Clark 

 Fork River. Fish are blocked from upstream migradon by Milltown dam, severing connectivity 

 with the rest of the Clark Fork River. The population staus of the nearby populations is 

 functioning appropriately in the Blackfoot River and functioning at unacceptable risk in the 

 upper Clark Fork River. Therefore, this indicator was rated as functioning at risk. 



4) Persistence and Genetic Integrity: Adjacent subpopulations in the Blackfoot and upper Clark 

 Fork Rivers are not functioning appropriately. Their population sizes are depressed, they are 

 persisting in areas of reduced habitat capability, in the presence of competing and hybridizing 

 species, and isolated from downstream populations by Milltown dam. Bull X brook trout hybrids 

 do exist in Rock Creek and brook trout do dominate in a number of the subwatersheds used by 

 bull trout for spawning. This indicator is rated as functioning at risk. 



Habitat Pathways: The following descriptions correspond to the 19 habitat indicators listed on 

 the f^S Matrix of Diagnostics/Pathways and Indicators for bull trout (USFWS 1998). Each 

 habitat indicator is described and rated at the appropriate scale - typically at the subwatershed 



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