| Abstract/Description or Keywords |
A habitat alteration exists as a result of three dams which now influence Arrow Lakes Reservoir: Keenleyside Dam, Mica Dam, and Revelstoke Dam. These dams have permanently altered the pre-existing ecosystem and have impacted native fish populations such as bull trout. Critical informaton is needed to manage bull trout effectively including identifying natal spawning and rearing habitats, determining age of initial migration to the reservoir, and defining overall stock structure. We determined the chemical composition of bull trout otoliths collected from the Arrow Lakes Reservoir (Nakusp creel survey), the Halfway River, Greeley Creek, McDonald Creek, Illecillewaet River, Incomappleaux River, Caribou Creek and Kellie Creek using Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS). The goal of this study was to develop a model for Arrow Reservoir bull trout that determines stock structure, migration timing, and location of spawning and rearing habitats for both current and future otolith samples. The results indicated that otolith chemistry analysis, through LA-ICPMS, is a useful technique for studying life history characteristics of fishes, specifically bull trout in the Arrow Lakes Reservoir. Strontium, Ba, Mg, Li and Mn provided symmetrical results throughout the otolith and the incorporation of these elements into the otoliths appears to be consistent over time. Most bull trout ages 1+ to 3+ years demonstrated significant movement among smaller tributaries in their larger rearing environment and reservoir entry occurred at approximately age 3+ for most of the individuals in this study. Validated classification accuracy using Discriminant Function analysis of juvenile bull trout was 94%. Seven out of nine unknown adult bull trout collected were classified to their natal tributaries while one individual was found to originate in the Arrow Lakes Reservoir. This study was effective in demonstrating that microchemical analysis of fish otoliths combined with Discriminant Function analysis is an effective stock assessment too for Arrow Lakes Reservoir bull trout. |
