With rising temperatures and a greater demand on water resources, NOAA Fisheries has identified reintroduction, or the intentional movement and release of endangered salmon back into their historical upstream habitat, as the only way to ensure their long-term conservation and recovery.
Today, steelhead and two populations of salmon (winter-run and spring-run Chinook) in California’s Central Valley are listed as threatened or endangered under the federal Endangered Species Act. These salmon and steelhead, known as salmonids, require cold water to survive hot summers, but dams block access to historically high quality habitat in high elevation areas, and the only habitat available to these fish is often of poor quality.
Dams Have Cut Off Salmonids
Barriers such as dams have cut off salmonids from 95% of the historical habitat. Dam construction between 1894 and 1968 has prevented fish from reaching high-elevation mountain streams where water is kept cool by melting snow. Instead, today fish are stuck below the dams on the valley floor. When salmonids spawn, their young depend on cold, clean water to survive. If they are restricted to lower elevation spawning areas below a dam, warmer water threatens their continued survival and leaves them highly vulnerable to the effects of a warming climate.
Reintroducing Endangered Fish Populations
Recovery of endangered fish populations in the Central Valley cannot be achieved without re-establishing populations back into the historical habitats that they are adapted to. In 2014, NOAA Fisheries released a recovery plan, analyzing the state of these species and detailing steps that were necessary for their recovery:
- They must be able to survive changes in annual precipitation due to climate change. Too much or too little water can be fatal during the wrong time of the year;
- Each year enough adults must return and spawn to support the population of the next generation; and
- There must be multiple populations in different rivers and streams from the northern to the southern portions of their range so that catastrophic events (such as disease and wildfires) don’t wipe out the entire species at once.
In order to meet these needs, NOAA Fisheries determined that reintroducing these species into their native habitat, coupled with the restoration of native floodplains, is essential to support healthy, resilient populations. With no way of getting upstream on their own, the endangered salmon must depend on us to get them there.
To learn more about reintroductions:
- Returning Winter-run Chinook salmon to the Native Habitat above Shasta Dam
- California Fish Passage: Frequently Asked Questions
- How Dams Affect Water and Habitat on the West Coast
- Designating Experimental Populations under the Endangered Species Act: Section 10(j)
- First Reintroduced Salmon Return to California Rivers in a Critical Step Towards Recovery
- 2021 Species in the Spotlight Winter-run Summary
Current Reintroduction Efforts
Winter-run Chinook Salmon above Shasta Dam
NOAA Fisheries is working with key federal, state, and tribal partners to return native Sacramento River winter-run Chinook salmon to chilly rivers above Shasta Dam where they once thrived. Reintroduction is essential to recovering these fish. Establishing populations in high-elevation habitats with cold water will reduce the overall risk from destructive events (catastrophic wildfire, prolonged drought, chemical spills, volcanic eruptions, etc.) and improve their overall resilience to impacts associated with climate change.
Winter-run Chinook salmon are one of the NOAA Fisheries Species in the Spotlight because they are in danger of going extinct. They are the only Chinook salmon species that migrate in the winter as adults and then spawn in the summer. They only live in one place, the upper Sacramento River.
Shasta and Keswick Dams block winter-run Chinook salmon from their historical habitat, limiting them to the lower reaches of the Sacramento River below the dams. On the floor of the Central Valley, air temperatures can average nearly 100 degrees Fahrenheit during the summer months, which affect water temperatures. Sacramento River Winter-run Chinook salmon spawn from late April to mid August, earlier than most species. Appropriate water temperatures are crucial to salmonid egg survival. This means that Sacramento River Winter-run Chinook salmon eggs are especially susceptible to warm water temperatures since they must survive the hot summer months. Cold water releases from Shasta Dam help offset the effect of warm water on salmon eggs and fry as long as enough cold water is available behind the dam. This can become tenuous during drought conditions.
During the 2012-2016 drought, Shasta Dam lost its cold water pool which resulted in warm water releases to the winter-run Chinook salmon spawning grounds on the Sacramento River near the City of Redding, California. The warm water resulted in the death of between 95-98% of eggs and recently hatched salmon incubating in their redds (nests). In contrast, water temperatures in the McCloud River above Shasta Dam remained suitable throughout the drought; if the fish had been able to access these waters, survival rates would have been much higher.
Current reintroduction efforts are focused on Sacramento River winter-run Chinook salmon because they are endangered. A successful reintroduction of Sacramento River winter-run Chinook salmon would also benefit Central Valley spring-run Chinook salmon and Central Valley steelhead. Both of which are also blocked from their historical habitat by the same dams.
Battle Creek Winter-Run Chinook Jumpstart Project
In 2018, 215,047 juvenile fish from Livingston Stone National Fish Hatchery were released into Battle Creek with the hopes that they would expedite a planned reintroduction effort into that tributary in the Upper Sacramento Watershed. As of January 2021 over 1,000 subadult and adult fish returned, showing a successful start to establishing a population outside of the mainstem Sacramento.
Establishing a self-sustaining population of Sacramento River Winter-run Chinook salmon in a second watershed (in addition to population in Sacramento River), such as Battle Creek, is a high priority and a major component of the Central Valley salmonid recovery plan.
Spring-run Chinook Salmon into the San Joaquin River
Central Valley spring-run Chinook salmon disappeared from the San Joaquin River after the construction of Friant Dam left portions of the San Joaquin River dry. In 1988, environmental groups sued the U.S. Bureau of Reclamation for violating California Fish and Game code 5937. They claimed that Friant dam did not direct enough water into the San Joaquin River to keep fish populations below the dam in good condition. On September 13, 2006, a settlement agreement was reached to restore and maintain fish populations in “good condition” and created the San Joaquin River Restoration Program (SJRRP).
For over ten years the agencies and individuals in the SJRRP have been working to reintroduce Central Valley spring-run Chinook to the San Joaquin River. In 2019 adult spring-run returned to the river and for the first time in over 65 years they were allowed to complete their life cycle in the southern extent of their range. This budding population still faces many challenges but three consecutive years of adult returns is the beginning of a reintroduction success story and will help to boost recovery and resiliency of Central Valley spring-run Chinook. Visit the SJRRP’s website to learn more.
Spring-run Chinook Salmon into the Yuba River
Following construction of Englebright Dam in 1941, spring-run Chinook salmon (and steelhead) were blocked from accessing high-elevation, cool-water habitat in the upper Yuba River. Currently, the population returns to the lower Yuba River and spawns below Englebright Dam. The feasibility of a successful reintroduction effort has been the subject of many studies and evaluations by a wide consortium of partners for almost twenty years. NOAA Fisheries and the California Department of Fish Wildlife are working with a variety of partners to build on past efforts and determine the most cost-effective methods for initiating an upper Yuba River reintroduction program, guided by the best available science and management techniques.
To pave the path forward for reintroduction, NOAA Fisheries has initiated a rule-making process under section 10(j) of the ESA to address stakeholder regulatory concerns of a Central Valley spring-run Chinook salmon reintroduction. This effort demonstrates a strong commitment to ensuring the future success of a reintroduction while protecting landowners and other stakeholders and their current lawful activities. Although funding for reintroduction has not yet been identified, we believe formulation of a plan guided by science can ultimately be funded. The quality and abundance of habitat above Englebright Dam offer exceptionally promising possibilities for the successful reintroduction of an independent population of spring-run Chinook salmon.