staging near spawning tributaries and may not have been residents 

 of this section. 



Six electrof ishing runs were required to obtain a sufficient 

 number of fish to calculate a rainbow trout population estimate 

 in the Scotty Brown section. Despite this effort, the rainbow 

 trout estimate in this section should be evaluated with caution. 

 The confidence intervals are wide, and the ability to split the 

 population into small length groups is limited due to low 

 recapture rates. 



The density of rainbow trout in the Scotty Brown section was 

 significantly lower than previous estimates (1980 to 1985) in the 

 Johnsrud section. Although estimates for the Johnsrud section 

 are not current and are for the late spring - early summer period 

 and are not directly comparable to the Scotty Brown fall 

 estimate, the differences in population are so large that a 

 comparison is meaningful. In the size group 4.0 to 10.9 inches, 

 there were 10 times more fish in the Johnsrud section than the 

 Scotty Brown section. Similarly, the estimated population of 

 adult rainbow trout (11.0 to 18.9 inches) was seven times larger 

 in the Johnsrud section (60/1,000 ft) than the Scotty Brown 

 section (8/1,000 ft) (Figure 11). 



The low numbers of rainbow trout in the Scotty Brown section 

 is difficult to explain, particularly for the small size groups. 

 The number of trout from 4.0 to 10.9 inches was considerably 

 below expected levels considering the large number of YOY rainbow 

 trout observed in this section during 1988 (Figure 11) . 



Compared to other rainbow trout fisheries in western 

 Montana, the Scotty Brown section demonstrates much lower than 

 expected population levels for a variety of size groups (Figure 

 12). The low number (23/1,000 ft) of rainbows 4.0 to 10.9 

 inches in length indicates that the large number of YOY in this 

 river segment experience high mortality, year classes prior to 

 1988 were considerably smaller or extensive movement prior to 

 their second summer of residence occurred. There does not appear 

 to be adequate numbers of juvenile fish to provide recruitment to 

 the catchable size classes in this river segment. 



In addition to low densities of rainbow trout in the Scotty 

 Brown section, trout are in relatively poor condition compared to 

 other rainbow trout fisheries in western Montana. In each of 

 three size groups where condition factors were compared, rainbow 

 trout in the Scotty Brown section demonstrated poorer condition 

 than rainbow trout in Rock. Creek and the Bitterroot River (Figure 

 13). Size groups were selected to evaluate potential changes in 

 trout condition as a response to growth and shifts in diet. 



Ten bull trout were captured and two large adults observed 

 with six days of electrof ishing effort on the Scotty Brown 



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