Seasonal dynamics of juvenile coho salmon (Oncorhynchus kisutch) in wetlands of the North Thompson River, British Columbia

Freshwater fish such as juvenile salmon may rely on dynamic and diverse habitats. The importance of freshwater wetlands to juvenile coho salmon in large river networks is not well known. I studied three wetland sites along the North Thompson River from May 2021 – May 2023 to understand how seasonal variation in wetland connectivity and water quality influence juvenile coho salmon habitat use. I used monthly mark-recapture sampling to estimate juvenile coho salmon abundances. Seasonal dynamics of juvenile coho salmon in wetlands was intertwined with connectivity and abiotic conditions. Juvenile coho salmon recruited as age 0 to wetlands during spring high flows but used wetland habitats year-round. Periods of high density, low oxygen, and high temperatures were associated with lower growth and abundances. This research advances understanding of the importance of wetlands and how they contribute to a mosaic of shifting habitats for juvenile coho salmon.