83 



TABLE 25. Estimated numbers (N/1000 ft) and biomass (lbs/1000 ft) of brown 

 trout by age groups in the Pipeorgan Section (8513 ft) of the 

 Beaverhead River between 1967 and 1976. Rainbow trout were too 

 scarce to estimate. 80% confidence interval in parenthesis. 



Brown Trout 



N/1000 Ft Lbs/1000 Ft 



IV & IV & 

 I II III Older Total I II III Older Total 



1967 Oct. 24 59 83 (±22) 136.5 136.5 (±38.4) 



1968 Apr. -- 51 24 21 96 (±23) 143.2 143.2 (±37.9) 



Oct. 88 60 27 175 (±39) 64.0 111.7 74.4— 250.1 (±69.4) 



1969 Oct. 83 96 18 <1 197 (±34) 52.6 167.5 47.8 .7 268.6 (±51.8) 



1970 Mar. -- 64 54 4 122 (±16) 47.2 83.8 9.9 140.9 (±17.7) 



Oct. 34 108 33 175 (±27) 22.6 174.9 80.4— 277.9 (±51.5) 



1971 Mar. — 32 74 32 138 (±37) 24.3 94.0 56.3 174.6 (±40.4) 



Oct. 72 35 70 177 (±29) 36.3 37.8 152.3— 226.4 (±41.0) 



1972 Mar. -- 72 43 51 166 (±21) 45.9 54.8 103.4 204.1 (±30.0) 



Sept. 33 47 26 29 135 (±28) 19.9 79.0 58.6 90.2 247.7 (±64.2) 



1973 Oct. 8 32 28 14 82 (±14) 4.8 53.0 75.0 49.3 182.1 (±34.3) 



1974 Mar. — 9 37 28 74 (±14) — 7.0 62.2 65.7 134.9 (±26.1) 

 1976 Mar. — 91 80 171 (±36) — 62.9 122.3— 185.2 (±35.6) 



