Yukon River Chinook Run Timing
Using environmental information to inform estimates of Chinook salmon spawning runs
Yukon River Delta. Image by Earth Observatory, NASA.
The Yukon River Chinook Run Timing Project is a collaboration between the Alaska Department of Fish & Game, the National Oceanic and Atmospheric Administration, and the Alaska Ocean Observing System. The goal of the project is to forecast the timing of the Chinook salmon run in the Yukon River Delta before each run.
These forecasts are designed to help fishery managers, Yukon River community members, and other stakeholders anticipate when the Chinook run will reach the YK-Delta, and how it is likely to progress through June and July.
The forecast model draws on historical commercial catch data, results from ADF&G’s Lower Yukon Test Fishery, and environmental indicators such as air temperature, sea surface temperature, and ice cover—sourced from multiple data providers.
Project Background
Chinook salmon, known for the longest annual freshwater migration of any salmon species, typically begin arriving at the Yukon River delta sometime between June 6 and June 26. Their timing is influenced by spring conditions like ice, temperature, and wind—but these vary each year, making it difficult to predict when the first pulse will enter the river.
The Yukon River is the longest river in Alaska and the Yukon Territory, stretching 1,980 miles from its headwaters in British Columbia through northwestern Canada and interior Alaska, before emptying into the Bering Sea at the Yukon-Kuskokwim Delta.
Accurate forecasts are critical, as early or late arrivals can lead fishery managers to overestimate or underestimate run strength, affecting harvest decisions along the river and potentially impacting both downriver and upriver fishing opportunities.
The forecast model is based on the relationship previously established in Mundy & Evenson (2011) which identified a set of three environmental variables which correlate with the run timing of Yukon River Chinook: April mean air temperature at the Nome, AK airport (1961–2025), May mean sea surface temperature (1961–2025) in the nominal marine staging area just off the Yukon River Delta, and the Spring-time proportion of ice cover (1970–2025), also measured over the nominal marine staging area.
The forecast predicts the dates of three Catch Per Unit Effort (CPUE) percentiles in the Lower Yukon Test Fishery based on the historical relationship with CPUE in commercial and test fishery catches on the Yukon River Delta (1961–2023) and the previously mentioned environmental indicators.
Previous Chinook Run Timing Forecast
Post-Season Analysis
AOOS Contact
Alice Bailey
bailey@aoos.org
Additional Information
The project is led by Bryce Mecum on a volunteer basis.
Principal Investigators
