Juveniles rear briefly in estuaries. Most Oregon chums migrate to the Gulf of Alaska for ocean rearing. Adults spawn at 3 to 5 years of age. Spawning occurs in lower mainstems, concentrated on large gravel bars. Adults are unable to pass even minor barriers.
Some coastal cutthroats migrate to the ocean.
But others may migrate only to the estuary or river main- stems, or they may not migrate at all. Those that do go to the ocean migrate out in the spring, stay only a few months close to shore, then return in the fall. The ones that migrate may rear in fresh water for several years before going to the ocean. They spawn in the winter and early spring, using small pockets of gravel. They may spawn more than once.