Chum usually return to their birth rivers to spawn after 2-4 years at sea. They are the last salmon in the season to return from the ocean. When in freshwater, chum feed on insects and other small creatures. Streams, coastal wetlands and estuaries are very important for chum salmon. On top of natural dangers from predators, some dangerous human activities are poor farming and forest practices, changing the flow of rivers, pollution and destruction of coastal wetlands and estuaries which are very important habitat for chum salmon who spend many months there before migrating out to sea.
Coho salmon are smaller and slimmer than the chinook salmon.
Coho salmon can reach up to one metre in length and weigh up to 14 kilograms but usually they weigh between 3 to 6 kilograms. Adult coho spawn from November to January and the eggs hatch the next spring. Young salmon, called fry, stay in their birth streams for over a year. After spending three years in the ocean, most adult coho return to their birth rivers to spawn. Some male fish return after just two years.