patterns can be explained by small sample size, variations in the hydrograph, and the 

 subsequent condition of migration corridors during the spawning out-migrations. For 

 example in October 2002, Blackfoot River flows near Bonner ranged from -560 to 410 

 cfs. Under these below normal conditions, bull trout remained in Copper Creek 

 presumably to avoid isolation in intermittent reaches or marginal wintering areas. In 

 contrast. October flows in 1996 ranged from -700 to 650 cfs during which time four 

 radioed bull trout exited Copper Creek. Isolated and marginal wintering areas near the 

 mouth of the Landers Fork may also influence this wintering behavior (Swanberg and 

 Bums 1997; Pierce et al. 2002). 



Spawning occurs in discrete areas, where groundwater inflows provide a 

 significant warming influence during winter compared to downstream non-spawning sites 

 where mid winter anchor ice formation common (this report. Results Part FV). These 

 upwelling areas have been shown to be important to embryo survival and the timing of 

 emergence (Weaver and Fraley 1991). 



Two of three Copper Creek fish survived the winter, and moved downstream 

 during spring runoff, to the middle Blackfoot River near original capture locations. The 

 forth bull trout that migrated into Copper Creek in 2003 did not survive the Snow-Talon 

 wildfire. The acute affects of wildfire (and possibly fire fighting activities) appear to 

 result in high mortality of bull trout in Copper Creek, based on sharp declines in redd 

 counts (USPS data - this report Executive Summary). These losses (and potential post 

 fire impacts) underscore the risks posed by catastrophic events on what is essentially the 

 only fluvial spawning population for the entire upper Blackfoot watershed (Swanberg and 

 Bums 1997, this report). This population appears to possess distinct life history traits 

 necessary for population resiliency and long-term population viability. Isolation of a 

 portion of the population caused by natural dewatering makes this population even more 

 vulnerable to catastrophic events such as severe wildfire (Swanberg and Bums 1997; this 

 report) and other disturbance. Fortunately, this study identified Copper Creek fluvial bull 

 trout between Lincoln and Nevada Creek - far below the area of anticipated post-fire 

 impacts. These fluvial fish should provide a higher level of resiliency than previously 

 reported (see Swanberg and Bums 1 997). 



We tracked only one non-spawning migratory bull trout. This sub-adult fish 

 captured near Lincoln Gulch, entered a spring creek tributary in April, presumably to 

 avoid high flows, a common movement pattem in the Rock Creek watershed (Eric 

 Reiland, FWP personal communication). It returned to its capture location in the 

 Blackfoot River in June where Ln remained imtil killed by a predator in October. This 

 fish remained in the river during summer in a reach where maximum summer 

 temperatures were < 65 "F, or - 5 to 12 ° F lower than Blackfoot River below Nevada 

 Creek (Appendix I). By contrast, a majority of migratory non-spawning fish in the lower 

 river ascend cooler tributaries in mid-summer presumably to avoid unfavorable summer- 

 time temperatures of the lower Blackfoot River (Swanberg 1997). 



Oiu- study documented the mortality of five bull trout (50 %). Sources included 

 one mammal, one suspected poaching, one to the Snow-Talon wildfire, and two 

 unknovms. Increases in visible avian inflected scars (talon and beak scars) on bull trout 

 were observed by FWP biologists during field sampling during the drought period. Bull 

 trout have also been observed holding in "vulnerable" habitats, including shallow waters 



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