The Chinook Salmon has 17 distinct Evolutionarily Significant Units, (ESU) in the US only, two of which are endangered and seven of which are threatened.
Sacramento River Winter Run,
Upper Columbia River Spring Run
Snake River Fall Run,
Snake River Spring/Summer Run,
Central Valley Spring Run,
Central Valley Fall Run
S. Oregon/N. California Coastal,
Upper Klamath Trinity,
Mid Columbia Spring Run,
Upper Columbia Summer/Fall Run,
Deschules Summer/Fall Run
Many agencies have been set up to protect this species, including the Pacific Fisheries Management Council, the North Pacific Fisheries Management Council, and the National Marine Fisheries Service. The federal Magnuson-Stevens Act was made to protect the Essential Fish Habitat, the waters and substrates necessary to fish for spawning, breeding, feeding and growing to maturity. The Sustainable Fisheries Act has amended the Magnuson-Stevens Act.
The main causes for the declining fish populations are overfishing, damming and diverting water, habitat destruction, and introducing hatchery populations. Overfishing has decreased population sizes enough that all other causes, along with natural predation, can have extreme effects, and population sizes decrease rapidly. Damming causes decline because it blocks adults from returning to their birthplace and because smolts often get sucked into the turbines of hydroelectric dams and are killed. Diverting water away from salmon streams causes water temperature to rise, reducing the oxygen carrying capacity of the water. Temperatures could also become fatally high in the summer. Reduced water levels could expose eggs in the winter, or flows could be too low to carry smolts out to sea. Habitat destruction, including logging, clearing rivers, pollution, and wetlands destruction, take away shade and necessary protection for juveniles. After logging has changed runoff patterns, streams may contain too much silt and become uninhabitable. Pollution can cause many physiological problems, including increased susceptibiity to pathogens. Introducing hatchery populations adds to the decline because the introduced populations interbreed with the native populations and can reduce resistence to disease (Pacific States Marine Fisheries Commission, 1996; National Wildlife Federation, 2002; NOAA, 2001; University of Wisconsin Sea Grant Institute, 2002; Arkoosh and Collier, 2002).
US Federal List: endangered
CITES: no special status
State of Michigan List: no special status