YCT Multi-state Assessment February 10, 2003 



Introduction 



Within the last 20 years several status assessments have been conducted for Yellowstone 

 cutthroat trout {Oncorhynclms clarki bouvieri; YCT) over part' or all of their historic range 

 (Behnke 1979: Hadley 1984; Varley and Gresswell, 1988; Thurow et al. 1988; Gresswell 1995; 

 May 1996; Kruse et al. 2000; Meyer et al 2003). Many of these assessments were either 

 conducted over only a portion of YCT historic range, involved only a few experts with specific 

 detailed knowledge of the assessment area, or suffered from a lack of consistency in the sources 

 of information used. TTiis report updates the past assessments using a protocol that was 

 consistently applied throughout the historical range of YCT. We assessed the historically 

 occupied range, current distribution, general abundance and genetic status, and risks for YCT 

 throughout their historical range. Fisheries professionals from Montana, Idaho, Wyoming, 

 Nevada and Utah (state agencies. Park Service, USPS, BLM, tribal, private, etc.) provided the 

 information for this assessment. State fisheries staffs identified and designated "conservation 

 populations", but information from many different sources was used to assess risks and threats to 

 these populations. TTie information for this status update was primarily compiled during the later 

 part of 2001. While this assessment provides consistent and relatively current information on 

 YCT that can be used by the PWS in relation to their responsibilities under ESA. the longer- 

 term, and probably more significant use of this assessment, is as an information base to be used 

 by individual states and other agencies, working collaboratively, to assess, plan and prioritize 

 their ongoing and ftiture YCT conservation efforts. 



The five states where YCT occur have the primary responsibility under their respective state 

 laws to manage and conserve YCT. Within specific portions of YCT range. Tribal governments 

 and the National Park Service assume managerial authority for conservation and management of 

 YCT. The Forest Service, BLM and other federal land and resource management agencies play 

 an essential role because of a responsibility for management of aquatic habitats on federal lands 

 and for coordination of land uses consistent with laws, rules, and regulations. The FWS is 

 charged with administration of the federal Endangered Species Act (ESA) and they concluded 

 that the petition to list YCT did not contain sufficient or substantial information to indicate that a 

 listing may be warranted. It is mutually beneficial for the above parties to work together to: 

 further the collective knowledge, implement conservation actions, and provide the best scientific 

 information to further YCT conservation. 



Analysis Area 



The analysis area included all of the known historical range of YCT within the western United 

 States. We relied primarily on Behnke ( 1 992) to delineate the likely historical range (Figure 1 ). 

 This area includes, from east to west, the upper portions of the Yellowstone River drainage 

 within Montana and Wyoming and the upper Snake River drainage in Idaho, Wyoming, Nevada 

 and Utah. This assessment does not provide an assessment of YCT that have been introduced 

 into areas outside of the historical range. 



Executive summary of YCT status assessment completed for Montana in 1999. Author: Bruce E. May. 



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