Executive Summary 



The 2002 and 2003 reporting period was a time of continued drought in the 

 Blackfoot Watershed. The drought began in 2000 and involved elevated summer water 

 temperatures, below normal mid-summer and winter flow conditions, and extreme 

 wildfires. The drought contributed to fish population declines in the Blackfoot River and 

 many tributaries. Despite the drought, fish populations in many restored streams 

 responded positively to riparian improvements. 



Compared with 2000, total trout densities (> 6.0") declined at two long-term 

 monitoring locations (Johnsrud and Scotty Brown Bridge) on the Blackfoot River in 

 2002. Declines occurred primarily with small-to-intermediate rainbow trout in the lower 

 river (Johnsrud section), whereas densities of larger rainbow trout increased. Westslope 

 cutthroat trout (WSCT) densities (> 6.0") remained generally stable between 2000 and 

 2002 after gradually increasing through the 1990s. Densities of Blackfoot River bull trout 

 (> 6.0"), also increasing through the 1990s, were generally stable in the lower river 

 between 2000 and 2002 (increase in the Johnsrud section and a decline in the Scotty 

 Brown section). Densities of lower Blackfoot River brown trout (> 6.0"), also increasing 

 through the 1990s, were similar between 2000 and 2002 (Results Part II). 



In 2002, we established a new Blackfoot River population survey site - the Wales 

 Creek section (river miles 60.0 to 66.2) 

 downstream of Nevada Creek. This 

 survey section supported much lower 

 total trout densities (> 6.0") than earlier 

 up-river (near Arrastra Creek) surveys 

 (Pierce et al. 2000) and lower Blackfoot 

 River survey sections (Figure 1). 

 Because of very low densities, we were 

 unable to generate population estimates 

 for bull trout, WSCT and rainbow trout in 

 the Wales Creek section. We did 

 generate an estimate for brown trout, the 

 dominant game fish in the section. 

 Brown trout densities were very low 

 compared with the lower Blackfoot River 



Oensity/1 000 feet 



Scotty Brown Wales Creek 



>6.0 inches 



Figure I. Estimated trout population densities for three 

 locations of the Blackfoot River. 2002. 



(Jonsrud and Scotty Brown Bridge) sections. Low trout densities (all species) in the 

 Wales Creek section apparently result from weak recruitment, which likely stems from 

 low juvenile densities, reduced water quality and fisheries-impaired (habitat) tributaries in 

 this section of the Blackfoot River (Maguire 1991, Ingman et al. 1990, Pierce et al. 2001, 

 Results Part IV). 



During the drought of 2002 and 2003, fisheries monitoring on 19 project streams 

 (Results Part III) showed a wide range of population responses. In general, populations 

 declined during the drought; however, we found several populations at higher densities in 

 streams where restoration projects were implemented during drought compared with pre- 

 project (and pre-drought) conditions. These results confirm the importance of correcting 

 human-caused limiting factors in streams as a means of increasing the resistance of 



