Electronic Thesis and Dissertation Repository


Master of Science




Dr Yolanda Morbey


The timing of smoltification in juvenile anadromous salmonids is important to ensure individuals match their preparedness with their migration timing and the optimal conditions in the environment. I performed the first study of smoltification in adfluvial juvenile Chinook salmon naturalized in the Laurentian Great Lakes. In a hatchery study, I found that juveniles from one of these populations have similar patterns of smoltification timing to individuals from anadromous populations. Their Na+/K+ ATPase activity, a common indicator or smolt status, peaked at 7.7 μmoles ADP/mg protein/hour on July 1 in freshwater. During the peak period, individual body size was not a good predictor of ATPase activity (R2 = 0.05, P = 0.168). This is evidence that body size is not as important to an individual’s decision to smolt and out-migrate as seasonal timing. My study also provides a valuable data set for future studies investigating rapid adaptation in Pacific salmon introduced into adfluvial environments.