But there are lots of differences between them too in how they look and in how they live. Average adult chinook are about 90 centimetres long and weigh 14 kilograms. Chinook lay their eggs, or spawn, in late summer to late fall in larger and deeper streams than other salmon. Young salmon usually stay in their birth river for 1 to 18 months. Then they travel towards the ocean where they stop to spend time in estuaries, where they remain up to 189 days.
Estuaries are places at the mouth of a river where fresh water and salt water mix.
There are usually lots of wetlands in which to hide and lots of food to eat. After leaving the estuary, chinook salmon spend 1 to 8 years at sea before returning to their birth stream to spawn. Chinook feed on insects and other small creatures while young and mostly on other fish when older. Poor forestry practices, dams and water diversions that change the river are very dangerous to young salmon as well as natural predators like birds and other fish. Destruction and pollution of estuaries is also a big problem.