© Joseph Dougherty. All rights reserved.
Oncorhynchus tshawytscha (Walbaum, 1792)
Chinook salmon may spend one to eight years in the ocean (averaging from three to four years) before returning to their home rivers to spawn. Chinook spawn in larger and deeper waters than other salmon species and can be found on the spawning redds (nests) from September through to December. After laying eggs, females guard the redd from four to 25 days before dying, while males seek additional mates. Chinook salmon eggs hatch, depending upon water temperature, 90 to 150 days after deposition. Egg deposits are timed to ensure the young salmon fry emerge during an appropriate season for survival and growth. Fry and parr (young fish) usually stay in fresh water 12 to 18 months before traveling downstream to estuaries, where they remain as smolts for several months. Some chinooks return to the fresh water one or two years earlier than their counterparts, and are referred to as "jack" salmon. "Jack" salmon can be half the size of an adult chinook salmon, and are usually released by sportsmen, but kept by commercial fishermen.