5-Year Review : Summary and Evaluation of Central Valley Spring-run Chinook Salmon Evolutionarily Significant Unit

Many West Coast salmon and steelhead (Oncorhynchus sp.) stocks have declined substantially from their historic numbers and now are at a fraction of their historical abundance. There are several factors that contribute to these declines, including: overfishing, loss of freshwater and estuarine habitat, hydropower development, poor ocean conditions, and hatchery practices. These factors collectively led to NMFS listing of 28 salmon and steelhead stocks in California, Idaho, Oregon, and Washington under the Federal Endangered Species Act (ESA).