A 0.13- to 0.23-inch [0.33- to 0.58-cni) mesh net was stretched across the stream to 

 block fish from moving out of the sampling area prior to the explosion. The net and the 

 effectiveness of prima cord assured an unbiased collection of close to 100 percent of 

 the fish population within each sample area. All collected fish were identified and 

 total length measured. 



Fish in lower Lodgepole and Curtis Creeks were also collected with a Smith-Root 

 type V electrof isher in 1974. The stream was stratified into 26-foot (7.9-m) sample 

 sections. A net was used to block the downstream end of each study plot so fish could 

 not escape downstream. Each reach was electrofished upstream and then back downstream. 



The upstream and downstream collections were kept separate and all fish identified 

 and measured. The two separate population numbers were then regressed to gain an 

 estimated total population using the two-catch method described by Seber and Le Cren 

 (1967). 



These two streams were continuously electrofished to determine how fish community 

 structure changed as distance from the river and channel elevation increased. Curtis 

 and Lodgepole Creeks were electrofished completely from their mouths 1,144 yd (1,046 m) 

 and 1,733 yd (1,585 m) respectively upstream. 



RESULTS OF TRIBUTARY SURVEY 



Tributary Streams Used by Salmon 



Summer chinook salmon, although considered primarily a river fish, utilize most of 

 the tributaries in the upper 50 miles (80 km) of the SFSR for rearing and minor spawning 

 Of the seven secondary and 16 primary tributary streams sampled for fish, one secondary 

 and 11 primary streams contained chinook salmon (table 1) . (Primary tributaries empty 

 directly into the SFSR, while secondary tributaries empty into a primary tributary) . 



Chinook salmon could occur in other streams, but manmade blocks keep them out. 

 Our random sample design could have caused us to miss some reaches containing chinook 

 salmon. Tailholt Creek contains rainbow trout but no chinook salmon because a dam 

 blocks this stream. The first sampling station on Four-Mile Creek was 0.5 mile (0.8 km) 

 above the mouth and even though no chinook salmon were found in or upstream from this 

 area it is possible they could rear downstream from this point. Both Cougar and Six-Bit 

 Creeks are relatively large tributaries and based on findings in adjacent tributaries 

 were expected to rear chinook salmon. However, salmon were not found in any of the 

 sample areas. 



Stream Reaches Most Used by Salmon 



Fifty-eight percent of the juvenile summer chinook salmon were rearing in stream 

 reaches within 440 yd (400 m) of the river (table 2). In Tyndail, Trail, Dollar, Black- 

 mare, and Fitsum Creeks, some of the larger streams in the study area, chinook salmon 

 were found only in the first 440 yd (400 m) of stream. If stream size had been a 

 dominant factor it would be expected that chinook salmon would rear further up these 

 streams than they did. 



4 



