Atmospheric rivers (ARs) drive hydrometeorological variability, influencing precipitation, river
discharge and water temperature. This study quantifies how ARs contribute to precipitation and
hydrology in the Gaat Héeni (Silver Salmon River) Watershed, a key migration corridor for
Sockeye Salmon. I integrate ERA5-Land reanalysis and the SIO-R1 AR catalog with in-situ
hydrometric measurements and biological monitoring data, including video observations at a
waterfall barrier and escapement counts from a weir. This approach enables me to evaluate how
AR-driven changes in hydrologic conditions subsequently influence Sockeye Salmon migration
success.
Sockeye Salmon jump success, modelled using logistic regression, was primarily influenced by
river discharge, with peak success occurring at 10–12 m³ s⁻¹ discharge levels. Jump success at
SR3-3 declined at discharge levels above 16 m³ s⁻¹ or below 9 m³ s⁻¹. Although water
temperatures of 13–15 °C coincided with optimal jump success, water temperature was not a
statistically significant predictor, reducing confidence in its influence relative to discharge.
Results show that AR events contributed between 15.9% and 39.1% of seasonal precipitation
from 1991 to 2023, with the highest contributions in fall (37.9%) and winter (24.1%). During the
2024 monitoring season, an AR event on 22–24 July triggered a discharge surge from 8.7 to
30.0 m³ s⁻¹ within two days, reflecting the watershed’s rapid hydrologic response. Centroid lag
analysis revealed a median discharge lag of 1.6 days following AR-driven precipitation,
underscoring the sensitivity of discharge timing to ARs.
