| Bull trout (Salvelinus confluentus) distribution and abundance were evaluated using resource selection functions in the Kakwa River watershed, Alberta. Presence of bull trout was more likely in higher stream orders, streams with low levels of fine sediments and low timber harvest. This model was used to evaluate responses of bull trout occurrence when timber harvest was simulated at 10%, 25%, 50% and 75% increases across the watershed. In each simulation, bull trout occurrence declined by 20% to 60%.; Zero-inflated poisson regression was used to show that bull trout abundance was higher at sites on higher stream orders, elevation, distance fished and fine sediment. Results from this research suggest risk to persistence of bull trout when timber harvest levels and road densities increase. In each case, increases in these anthropogenic perturbations resulted in loss of bull trout occurrence and density. Land management decisions should incorporate these landscape-level responses by bull trout if this species is to persist. |
