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.
Most coho fry feed on underwater insects and small fish. Poor forest and farming practices can cause erosion which is washing away of dirt which can cover up spawning beds or smother eggs. Migrating coho salmon also face dangers from dams and from low water levels when water is taken for farming or for making electricity. Pink salmon can be up to 76 centimetres in length and weigh up to 5.5 kilograms but on average, pink salmon usually weigh from 1.5 to 2.5 kilograms. Pink salmon begin to move downstream towards the ocean almost right after hatching from their eggs and coming out of the gravel.