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

Freshwater fish such as juvenile salmon often rely on dynamic and diverse
habitats. The importance of freshwater wetlands to juvenile coho salmon in
large river networks is not well known. We studied three wetland sites
along the North Thompson River, British Columbia, Canada, from May 2021 –
May 2023 to understand how seasonal variation in wetland connectivity and
water quality influence juvenile coho salmon habitat use. We used monthly
mark-recapture sampling to estimate juvenile coho salmon abundance.
Seasonal dynamics of juvenile coho salmon in wetlands were intertwined
with connectivity and abiotic conditions. Age-0 juvenile coho salmon
recruited to wetlands during spring high flows and used wetland habitats
year-round. Periods of high density and low oxygen were associated with
lower growth and abundance. In addition, our study provides information on
the timing of juvenile coho salmon use of wetland habitats which can be
used to inform habitat managers of times of year that pose the greatest
risk and benefits to these fish.

淡水鱼类（如幼鲑）通常依赖动态多变且类型多样的栖息生境。目前学界对于大型河网中的淡水湿地在幼年银大麻哈鱼（coho salmon）保护中的重要性仍不甚明晰。本研究于2021年5月至2023年5月期间，在加拿大不列颠哥伦比亚省北汤普森河沿岸选取三处湿地样点，旨在探明湿地连通性与水质的季节变化如何影响幼年银大麻哈鱼的生境利用模式。研究采用月度标记-重捕采样法估算幼年银大麻哈鱼的种群丰度。结果显示，湿地内幼年银大麻哈鱼的季节动态与其连通性及非生物环境条件密切相关。0龄幼年银大麻哈鱼会在春季高流量时段补充进入湿地，并全年利用湿地生境。种群高密度与低氧条件并存的时段，往往与较低的生长速率和种群丰度相关。此外，本研究明确了幼年银大麻哈鱼利用湿地生境的时间节点，可为栖息地管理者提供该鱼类全年各时段所面临的最高风险与最优获益时机的参考依据。