Though chum salmon once had a wide geographic distribution extending as far south as California, currently the southern extent of their distribution is only to the mid-Oregon Coast. Historically, they contributed up to 50% of the biomass of Pacific salmon. Chum migrate only a short distance from the ocean, entering freshwater after fall rains raise river levels, and juveniles migrate to salt water immediately after hatching. Consequently, chum are sensitive to conditions in estuaries and coastal habitats. They typically spend 3-5 years in the ocean before returning to spawn.
There are two evolutionarily significant units (ESUs) for chum salmon in Oregon: the Pacific Coast ESU and the Columbia River ESU, both of which span both Oregon and Washington. Chum have been extirpated from the Oregon portion of the Columbia River ESU.
No data are currently available for chum.