WCT Multi-state Assessment February 10, 2003 



system primarily on information compiled by Willock (1969). Hanzel's (1959) inclusion of 

 many of these areas was based on creel census information that he acknowledged was of 

 questionable value due to the inability of some anglers to differentiate between cutthroat trout 

 and other species. While Willock (1969) found WCT "limited to the cooler waters of the North 

 Fork of the Milk River" in Alberta. Canada, he points out that the North Fork of the Milk is 

 connected to the St. Mary's River in the South Saskatchewan system via the St. Mary's Canal 

 that flows from the St. Mary's to the North Fork. We have included the St. Mary's drainage in 

 the historical range, but excluded the Milk because WCT originating from the St. Marj's may 

 have colonized the North Fork of the Milk through the St. Mary's Canal. Whether the 

 headwaters of the Milk River were historical WCT range will probably never be known with 

 certainty. 



The Upper Musselshell was included in many previous assessments as part of the historical range 

 of WCT (Hanzel 1959; Behnke 1979 and 1992; Shepard et al. 1997; U.S. Fish and Wildlife 

 Service 1999). but we excluded this 4*^ code HUC based on the fact that neither historical nor 

 current fish surveys found any WCT populations in this HUC and we have several anecdotal 

 accounts, including one historical newspaper article (Castle News. April 26, 1888). and Hanzel's 

 thesis (1957) indicating that this portion of the Musselshell drainage was barren offish until 

 stocking occurred in the late 1800's. probably by U.S. Army troops (letter to B. Shepard from R. 

 Behnke 1996). WCT populations currently occur within two tributaries to the lower Musselshell 

 River. Box Elder and Flatwillow creeks. We suspect that the WCT population in Half Moon 

 Creek, a tributary to Flatwillow Creek, originated from a drainage divide transfer from the Judith 

 River drainage, while the Collar Gulch population in Box Elder Creek was probably stocked (see 

 above in Results). 



We estimated that slightly over 33,000 miles of habitats in Montana historically supported WCT 

 and that the South Saskatchewan, Missouri, and Columbia basins contained about 0.5%, 51.6%, 

 and 47.9% of the historical range, respectively. Liknes and Graham (1988) conservatively 

 estimated that approximately 25,500 km (15,845 miles) of stream habitats in Montana were 

 historically occupied by WCT, based primarily on earlier work by Liknes (1984), and that the 

 Saskatchewan, Missouri, and Columbia basins contained about 0.9%, 44.7%, and 54.4% of the 

 historical range, respectively. While Liknes and Graham's estimates of the total historical 

 habitat occupied by WCT in Montana was less than half the amount we estimated, the 

 proportions of this habitat that were distributed in each of the three major basins were similar. 

 The difference in total length of historical habitat may have been related primarily to the 

 different scales at which these assessments were done (1 :250.000 for Liknes and Graham's 

 assessment and 1 : 1 00.000 for this assessment). 



Van Eimeren (1996) estimated that Montana contained just over 57.000 miles of historical WCT 

 habitat. Shepard et al. ( 1 997) estimated that approximately 93.000 km (57.780 miles) of habitats 

 in the Missouri basin of Montana were historically occupied by WCT. We estimated that about 

 1 7.500 miles of habitat within the Missouri River basin of Montana were historically occupied. 

 While this difference was large. Shepard et al.'s earlier (1997) assessment included many 4"' 

 code HUC's that we excluded. Milk Headwaters, Willow, Bullwhacker-Dog, Box Elder, and 

 Upper and Middle Musselshell. Shepard et al. also made no effort to exclude any habitats within 

 those areas they believed were historically occupied. The discrepancy between Van Eimeren's 



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