YCT Multi-state Assessment February 10, 2003 



headwater streams. Hanzel's assessment was mostly qualitative and he made little effort to 

 quantify numbers of streams or miles occupied. Hadley (1984) completed an assessment of YCT 

 using Montana Fish, Wildlife and Parks' computerized database as an information source. Use 

 of the database allowed for a partitioning of YCT information into categories that were used to 

 gain a better understanding of YCT populations in Montana. Hadley (1984) reported that YCT 

 were believe to exist in 324 km (203 miles) of stream based on information contained in the 

 database at that time. Hadley also stated that the database was likely incomplete because at the 

 time it didn't contain information from Federal agencies nor have all the information from 

 department personnel. The significant difference in miles of occupied stream habitat between 

 the assessment (203 miles) completed by Hadley (1984) and our assessment (1,417 miles) is 

 likely do to insufficient data being available within the State's database at the time Hadley 

 completed her review. During the last 20 years there has been a substantial investment of time 

 and energy to prove better information of YCT distributions within Montana. As a result, many 

 more stream reaches have been inventoried and tested genetically, fri addition, the statewide 

 database has been updated on a regular basis of at least by-annually and included data from all 

 sources. 



Kruse et al. (2000) reported on the status of YCT within the Greybull and Shoshone River basin 

 of northwestern Wyoming. Their assessment was very detailed and provided information on 

 YCT distribution from 182 streams (1,705 km; 1,066 miles) within the two river basins. As part 

 of the Wyoming workshop for our assessment, the information collected by Kruse (2000) was 

 entered into the database which greatly strengthened the information on current YCT 

 distributions in Wyoming. In similar fashion, the work of Mark Novak, USDA Forest Service 

 and Wyoming Department of Game and Fish in the upper Snake River basin was included within 

 our assessment. 



Thurow et al. (1988) provided an assessment of YCT status and ecology within the Idaho portion 

 of the native range. Their work concentrated on many of the major tributary drainages to the 

 Snake River in Idaho (i.e. Blackfoot River, South Fork of the Snake River, Teton River and 

 Willow Creek). Specific quanfification of the amount of stream habitat occupied by YCT was 

 not pro\'ided but there were statements indicating the YCT were present in most streams and 

 stream reaches within these tributaries but there was a significant effort to quantify population 

 levels for streams occupied by YCT. Meyer et al.(2003) completed a very important follow up 

 assessment of many streams sampled in the 1980's by Thurow et al. (1988) and others. This 

 later sampling repeated population quantification at 77 pair sites following the same sampling 

 protocol to the extent possible. Meyer et al. (2003) found that population abundance had 

 remained relatively stable, at most paired sites, over the last 10-20 years. Only five of the sites 

 sampled in the 1980's did not contain YCT (Meyer et al.(2003). The sampling design of this 

 recent study made it impossible to provide definitive conclusions regarding YCT distribution and 

 population abundance outside of the study sites. 



Designated Conservation Populations 



There were two types of conservation strategies represented by the YCT "conservation 

 populations" (Appendix F). One strategy was linked to conserving genetic integrity and 

 reducing the influence of competitive species by isolating YCT populations (Kruse et al. (2001 ). 

 The other strategy emphasized maintenance of connectivity among YCT populations by 



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