WCT Multi-state Assessment February 1 0, 2003 



included current occupation by salmonids, historical journal entries, scientific reports, and 

 evidence of basin transfers by headwater stream captures. All stream and river habitat was 

 included within the historical range unless explicitly excluded by the fishery professionals. Our 

 delineation of historical range refines previous assessments of historical range. The amount of 

 historical range we estimated was then used as the baseline to compare to the current status. 



Barriers to Fish Movement 



Since barriers to upstream fish movement have important implications for both historical range 

 and current status, barriers that were believed to significantly affect distribution of WCT were 

 located and identified. Geological (i.e. bedrock waterfalls, naturally dry channel segments, etc.) 

 and anthropogenic barriers were located and classified. Geological barriers were considered 

 when potentially excluding lotic habitats from the historical range. Anthropogenic barriers were 

 considered when assessing current distributions and various risks to conservation populations. 

 Only barriers of believed significance were included; however, much of the area had not been 

 surveyed for barriers. Significance of barriers as they related to risk and consei-vation of WCT 

 was rated (Appendix B). 



Current distribution 



For the purposes of this assessment all stream segments of habitat currently occupied by WCT 

 within their historical range were included and some, but not all, stream segments occupied by 

 WCT outside historical range were included. We stratified the results to clearly show status 

 within and outside historical range. Stream segments where WCT populations were supported or 

 maintained by stocking were not included in current distribution; however, stream segments that 

 may have been stocked with WCT in the past, but currently were maintained exclusively by 

 natural reproduction were included. All waters that supported WCT and appeared on the LLID 

 hydrography layer, regardless of level of introgression, were included; however, the genetic 

 status of each stream segment was classified (see below). In addition to genetic status, a 

 determination was made on the relative abundance of WCT inhabiting each stream segment. 

 These results were summarized by length of habitat occupied and not by number of stream 

 segments occupied. Number of stream segments was not a meaningful measure because this 

 number does not equate to number of populations and lengths of stream segments varied widely. 

 The stream segment information was aggregated within the "conservation population" 

 assessment (see below). 



Genetic Status 



Seven classes identifying genetic status for stream segments were applied (Table 1). Five classes 

 were used for those stream segments that had been genetically tested and two classes for those 

 where no genetic testing had been done (Table 1). Genetic sampling involves many complex 

 issues that can make clear interpretation and reporting of results difficult, especially within 

 standardized databases (Appendix D). We will briefly address a few of these issues here, but 

 suggest reading Appendix D for more detail. 



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