Mitigation for the Construction and Operation of Libby Dam

Table 7. Average catch of westslope cutthroat trout per floating gill net caught in the Rexford
and Tenmile areas during the fall, average length, average weight, number stocked directly into
Libby Reservoir, and corresponding size of stocked fish between 1988 and 2003. The Tenmile
location was not sampled in 200-2003.
1988 1989 1990 1991 1992 1993 1994 1995 1996
No. Caught 0.50 0.32 0.32 0.32 0.50 0.50 0.14 0.07 0.21
Avg. Length (mm) 295 264 238 261 275 260 251 314 252
Avg. Weight (gm) 249 196 146 191 211 191 156 316 161
No. Stocked none 5,779 40,376 67,387 72,376 72,367 1,360 none none
Length (mm) n/a 33 104 216 190 287 n/a n/a
1997 1998 1999 2000 2001 2002 2003
No. Caught 0.11 0.14 0.11 0.07 0.21 0.07 0.21
Avg. Length (mm) 225 267 305 302 259 305 270
Avg. Weight (gm) 128 228 296 271 175 256 206
No. Stocked none none none none none none none
Length (mm) n/a n/a n/a n/a n/a n/a N/a
Kamloops Rainbow Trout (Duncan Strain)
Kamloops rainbow trout were first introduced to Libby Reservoir in 1985 by BCMOE.
The BCMOE continued stocking approximately 5,000 fingerling Kamloops (Gerrard strain)
annually into Kikomun Creek (a tributary to the Kootenai River) from 1988-1998 (L. Siemens,
BCMOE, personal communication). Montana FWP has stocked approximately 11,000 to
73,000 Duncan strain Kamloops rainbow trout since 1988 (Table 8). The catch of Kamloops
rainbow trout in fall floating gillnets (fish per net) was significantly and positively correlated
with the number of hatchery Kamloops rainbow trout stocked in the reservoir the previous year
(P=0.0003; r 2 = 0.66; Table 8) for 1989 through 2003. However, the catch rate of Kamloops
rainbow trout in fall floating gillnets shows no significant trend (Figure 34; r 2 = 0.09; p =
0.247). Catch rates for Kamloops rainbow trout in fall gillnets has been low since 1996,
averaging only 0.07 fish per gillnet.
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