Migratory diversity of juvenile salmon in a threatened estuary

Understanding how migratory species such as juvenile salmon (Oncorhynchus spp.) utilize key transition habitats such as estuaries can illuminate their vulnerability to pressures such as habitat alteration or climate change. This thesis examined the diversity of migratory juvenile salmon in the estuary of the vast Skeena River, Canada. First, I compared abundances of different species of juvenile salmon in different regions, and found that sockeye (O. nerka) and Chinook (O. tshawytscha) salmon were most abundant in areas proposed for development. These estuary salmon were genetically linked to dozens of locally-adapted populations from throughout the Skeena watershed and beyond. I also found that downstream migration timing was population-specific and related to the elevation of the different rearing lakes and distance travelled. Different populations encountered different zooplankton communities in the estuary. These results suggest that the Skeena estuary integrates multiple scales of salmon diversity, which could be compromised by impending habitat degradation.