Hydraulic and Habitat Spatial Correlations: Qualitatively (Figure 6A) there appears to be a positive correlation
between spawning location and both high maximum velocity and high maximum depth. To test this observation we
performed a spatial correlation between spawning location and maximum velocity and maximum depth by shifting
velocity and depth each over a 1.0 rkm range both upstream and downstream by 0.1 rkm increments (Figure 7). The
resulting correlations, reported as R
2 values and with significance at the 99
th percentile, while not particularly robust
show broad regions of positive correlation centered on the position of maximum velocity and depth. In addition, the
correlations fall off faster when shifting the velocity and depth downstream. Correlations calculated between the
average velocity and average depth but not reported here, were not as conclusive. The correlation results suggest
that the sturgeon are keying in on regions of highest velocity and greatest depth. This relationship has been
presented in many other studies of sturgeon spawning habitat. However, in this study we present a slight modification by suggesting that there is not a particular threshold velocity or even a specific range of velocity
sturgeon key on, rather, all other things considered such as sufficient discharge and temperature, they appear to key
in on the highest velocity and depth within the spawning region for the given discharge that is occurring when the
fish are physiologically ready to spawn. This apparent behavior suggests that fish, when ready to spawn, will seek
out the best perceived location to deposit eggs given the current environmental conditions. Under current flow
conditions the sturgeon must move through many of these high velocity or high depth regions before entering the
braided reach. Figure 6B shows simulated maximum velocity for four modeled discharges (values reported in figure explanation) which represent a range of flows close to the pre-dam mean annual peak flow (2200 cms) with both pre-dam high
and low Kootenay Lake stages. Prior to this study it has been hypothesized that higher pre-dam Kootenay Lake
stages damped velocities in the meandering reach and encouraged sturgeon to move into the braided reach. The
limited number of simulations performed in this study shows that while the velocity may be slightly reduced in the meandering reach under higher lake stages compared to lower lake stages, the variability in velocity remains. However another interesting pattern emerges from the simulations; the maximum velocity in the meandering reach
under the highest flows approach that of the maximum velocity in the transition reach thereby reducing the velocity
contrast that exists between the two reaches at lower flows. This reduction in velocity contrast is enhanced under higher Kootenay Lake stages. Perhaps the additive affect of high discharge and high lake levels reducing the velocity contrast in the transition reach rather than reducing the velocity in the current spawning reach encouraged
the fish to move up into the braided reach during pre-dam flow conditions where there was extensive suitable
substrate.