Appearance
Chinook Salmon, scientifically known as Oncorhynchus tshawytscha and commonly referred to as King Salmon, are the largest of the Pacific salmon, often exceeding 30 pounds. They are distinguishable from other salmonids by their robust, streamlined bodies, silver sides, and a blue-green back. During spawning, their coloration changes to a dark olive or reddish hue. Other identifying features include black spots on the upper half of their body, dorsal fin, and both lobes of the tail fin, and black gums at the base of their teeth.
Ecology
Chinook Salmon are anadromous, meaning they migrate from ocean environments to spawn in their natal freshwater streams or rivers. Their complex life cycle begins in freshwater streams and rivers, where they spawn in clean, cold, well-oxygenated water with gravel beds. Females create nests in the gravel beds called redds, where they lay eggs. Due to their size, Chinook Salmon are capable of spawning in larger gravel than most other salmon.
The young fish, called alevins, remain in the gravel and feed off their yolk sacs before emerging as fry to feed on small invertebrates such as insects and crustaceans. As they grow, fry develop into parr, which undergo physiological changes to become smolts as they prepare for their migration to the ocean. Juvenile Chinook Salmon will spend one year rearing in the riverine environment, before migrating to the ocean. Once in the ocean, they grow rapidly, feeding primarily on fish. After one to five years, they return to their natal rivers to spawn. This migration completes their life cycle. Chinook Salmon migrating to the Upper Columbia travel hundreds of miles and pass through seven to nine dams, depending on where they were born.
Juvenile Chinook are preyed upon by fish such as whiting and mackerel, and birds such as Bald Eagles and seagulls, while adult salmon face predation from marine mammals such as orcas and sea lions and larger fish like sharks. Salmon are also a primary food source for the endangered Southern Resident killer whales. After spawning, the carcasses of Chinook Salmon provide essential nutrients to river ecosystems, enhancing the growth and survival of newly hatched salmon by contributing nitrogen and phosphorous to streams.
Threats
Upper Columbia Chinook Salmon face numerous threats. These include habitat degradation from logging, mining, agriculture, and urban development leading to sedimentation and pollution as well as reduced habitat availability. Dams and culverts block access to spawning grounds and alter water flows, making migration challenging. Climate change affects their habitat by increasing stream and ocean temperatures and changing precipitation patterns.
Currently, two species of Chinook Salmon are listed as endangered under the Endangered Species Act (ESA), including the Upper Columbia River spring-run Chinook. Seven species are listed as threatened, and three are candidates for listing.
Conservation
Conservation efforts in the Upper Columbia focus on habitat restoration, fish passage improvements, hatchery programs, and regulatory protections. The role of UCSRB is to develop and coordinate implementation of the Upper Columbia Spring Chinook and Steelhead Recovery Plan. Habitat restoration projects aim to improve riparian areas and floodplains, remove barriers to migration, improve water quality, and enhance habitat complexity. Collaborative initiatives among government agencies, non-profits, Tribes, and landowners in the region enhance these efforts.
