Mitigation for the Construction and Operation of Libby Dam

Burbot per Trap Day
3
2.5
2
1.5
1
0.5
1995-2003
Model
Y = -0.387 + 4.014*X
r 2 = 0.47; p = 0.04
0
0 0.1 0.2 0.3 0.4 0.5 0.6
Catch per Net
Figure 39. The relationship between mean burbot catch per net for spring sinking gillnets on
Libby Reservoir and burbot catch rates (fish/trap day) of baited hoop traps in the stilling
basin below Libby Dam 1995-2003.
Total Fish Abundance
The long-term trends in total fish abundance in the reservoir reflect the changes that
have occurred in the reservoir since impoundment. Total catch (fish per net) for spring gillnets
has significantly increased since impoundment (Figure 40; r 2 = 0.104; p = 0.09; Table 9) is
indicative of an increase in the biomass of species that prefer reservoir habitats: peamouth
chub, suckers, northern pikeminnow, etc. However, there is no significant trend in total catch
(fish per net) for fall gillnets (Figure 40; r 2 = 0.003; p = 0.76; Table 10). Species composition
for the catch of fall and spring gillnets has remained relatively stable since 1988 (Table 11).
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