The Chinook salmon, Oncorhynchus tshawytscha, is the largest species in the pacific (Oncorhynchus) salmon family. Other commonly used names for the species include king salmon, Quinnat salmon, spring salmon and Tyee salmon. Chinook are an anadromous fish native to the north Pacific Ocean and the river systems of western North America ranging from California to Alaska. They are also native to Asian rivers ranging from northern Japan to the Palyavaam River in the Siberian far east, although only the Kamchatka Peninsula supports relatively persistent native populations. They have been introduced to other parts of the world, including New Zealand and the Great Lakes. A large Chinook is a prized and sought-after catch for a sporting angler. The flesh of the salmon is also highly valued for its dietary nutritional content, which includes high levels of important omega-3 fatty acids.

The Chinook is blue-green,red or purple on the back and top of the head with silvery sides and white ventral surfaces. It has black spots on its tail and the upper half of its body. Its mouth is often dark purple. Adult fish range in size from 33 to 36 in (840 to 910 mm) but may be up to 58 inches (1,500 mm) in length; they average 10 to 50 pounds (4.5 to 23 kg), but may reach 130 pounds (59 kg). The current sport-caught world record, 97.25 pounds (44.11 kg), was caught on May 17, 1985 in the Kenai River (Kenai Peninsula, Alaska). Some were found dead at well over 100 lb. The commercial catch world record is 126 pounds (57 kg) caught near Rivers Inlet British Columbia in the late 1970s.x