Average weight is 10 - 45 pounds, with a record of 126 pounds. The chinook has a greenish back, silver sides, and a silver belly. Its mouth is black. The fish darken as they mature. By the time the males are ready to spawn, they are almost black and their snouts have twisted into hooks.
Chinook usually mature in their third or fourth year.
However, it can be as early as the second year or as late as the eighth. The fish return to the Columbia in the fall, spring, and summer. Some types of chinook linger in deep pools in the river until the water is just right for moving on to their spawning grounds. Chinook are known as long-distance swimmers and will travel to the farthest reaches of the Columbia to spawn. They can release 3,000 - 7,000 eggs.