They then make their way up through the gravel and begin migration to the sea. Once in the sea, young chum salmon remain in river estuaries for several months, then move into the open ocean in the fall and winter of their first year. Most Alaskan chum salmon stay at sea for 2 to 5 years. They occupy the Chukchi and Bering Seas, disperse west along the Aleutian chain, and south into the Gulf of Alaska. The fish feed near the water's surface at night, and range down as far as 60 meters during the day.
Some coho salmon migrate a considerable distance into Interior rivers to spawn.
Coho salmon in the Yukon River drainage have been found spawning near Old Crow on the Porcupine River- almost 2,000 miles from the sea. Most spawning streams are narrow and shallow with a gravel substrate. Coho salmon also seem to favor streams with an upwelling of ground water. The female digs a redd, consisting of several pits, and deposits her eggs in the stream gravels. Alaskan coho salmon live in streams for at least a year before migrating to the sea.