The CDFW, along with several other state agencies, are taking emergency actions to save the California Chinook salmon population and reverse the effects of the drought.
LAKE SHASTA- The California Department of Fish and Wildlife announced on May 9 that it will be testing a pilot project this fall for winter-run salmon, to be able to access their historical spawning grounds, get past dams, and other challenges these waterways are presenting them.
California’s severe climate-driven drought has had a significant impact on the state’s water supply, but it’s also putting the state’s salmon population at serious risk.
Managing California’s water needs during this water supply crisis implies minimizing the impacts of drought and water management on the environment while meeting the health and safety needs of communities and supporting the economy and agriculture. The Department of Water Resources (DWR) and Department of Fish and Wildlife (CDFW) are working to respond to drought and climate change impacts on native species and ecosystems.
Scientists and fish biologists from DWR and CDFW have a long history of working together to protect and support California’s salmon populations. Collaborating through shared projects, funding, and research efforts, DWR and CDFW are identifying critical challenges facing salmon and using the best available science and technology to find ways to promote salmon health and survival.
The water from Shasta Lake coming out of the Sacramento River is shared by cities, farms, residents, and fish. Those departments are the primary water needs, and supporting the Delta ecosystem requires a balancing act among those groups and interested agencies.
“Salmon are a cold-water fish species; they need cold water, and there’s just not a cold-water supply in Lake Shasta because the water levels are low,” said Peter Tira, public information officer for the CDFW. “So, what we’ve done the past couple of years is when the salmon return to spawn, the winter-run especially, they spawn in Redding, basically below the dam at the hottest part of the year during summer, and if they are successful at spawning the water is too warm for those eggs to hatch or even for the juveniles to develop properly.”
Likewise, winter-run salmon are an endangered species and the most likely to face extinction. Their life cycle has been hard hit by climate change and drought. These fish would ordinarily swim up through Sacramento and then move up through the Sacramento River into tributaries, where water conditions are cold and conducive to spawning. They haven’t been able to do that since constructing the dams for Shasta Lake. Therefore, the salmon are stuck at the base of those dams in the middle of summer.
“So, we’re taking some emergency actions this year,” said Tira. “We’re moving winter run[salmon]… and physically driving them to the North Fork of Battle Creek, which is their historic spawning grounds; there are some barriers that prevent them from getting to that colder water, so we are physically driving them, and releasing those adult winter run to spawn.”
The CDFW is also transferring the spring-run chinook to the upper regions of Clear Creek in northern California.
“We need to make sure these fish survive,” said Tira. “They typically have a three-year life cycle, and this will be the third year of a drought, so if [California] has another bad production year, the whole species faces a threat. So we’re going to test what we call a juvenile collection system this fall along with the department of water resources so that these salmon are able to get past the dams and access their historical spawning grounds.”
There are too many predators and obstacles for the juvenile salmon; therefore, they will be collected and redistributed to Shasta Lake.
The state has embarked on dozens of projects to ensure the success of California’s salmon populations. These projects include restoring critical habitats for salmon and other fish species, improving salmon migration corridors to and from the ocean, and increasing monitoring efforts to track the status of populations better and devise new strategies to improve their status.
Significant course diversions and several channels and pumping instruments construct the Delta.
“These fish have to get through the Delta, and [improving salmon migration corridors] it’s really for when they return from the ocean and navigate the Delta,” said Tira. “So, for example, around the southern bypass, we did some vegetation removal. It’s things like putting screens up on these pumping areas so that they don’t pull in salmon or so salmon don’t get diverted into these canals and get stuck. It’s addressing their migration quarters and where they run into problems. It addresses the whole migration needs from the ocean to the rivers and back.”
Among the recent highlights:
- In April, DWR and CDFW staff began work to remove vegetation from a critical migratory path for adult spring-run Chinook salmon in the Sutter Bypass that runs parallel to the Sacramento River southwest of the Sutter Buttes. Each year, from February through June, salmon migrate through the East Borrow canal of the bypass on their way to spawning grounds near Chico. Waters are warmer in the bypass because of the severe drought and changing climate, resulting in extensive overgrowth of aquatic vegetation that impedes adult salmon migration. DWR and CDFW scientists are working to clear this migration pathway and ensure improved mobility and water quality for migrating adult spring-run Chinook salmon returning to their spawning grounds. A video of the project is available on the DWR YouTube channel.
- Further up the Sacramento River, returning salmon will find a new side-channel with gravel suitable for spawning and riverbank vegetation to help reduce water temperatures. The warming climate and dry conditions lead to increased river temperatures that can have fatal consequences for salmon. The new side-channel was designed by DWR engineers and constructed by a tribal contractor near Anderson at a location where DWR and CDFW scientists observed numerous salmon taking advantage of the calmer waters to spawn. The side channel doubles as a place where juveniles can grow and thrive after hatching and emerging from the gravel. Similar activities to improve spawning locations by applying suitable gravel have occurred in the Feather River, the Sacramento River’s largest tributary, and more are being planned.
- Also underway along two tributaries of the Sacramento River in Tehama County is an enhanced research and monitoring project for spring-run juvenile salmon in Mill and Deer creeks by CDFW biologists underfunding by DWR. These are two of a handful of streams in the Central Valley that still support the unique yearling-type juvenile salmon, which remain in the waterbody after hatching for nearly a year before beginning downstream migration and are believed to be the only salmon from these two streams that survive drought conditions and eventually return to spawn. Yearling-type juvenile salmon were plentiful in streams across the Central Valley before dam construction and were likely a critical factor in the resiliency of Central Valley salmon populations.
- A significant multi-agency effort is underway to assist the migration of winter- and spring-run adults and juveniles around dams on the Upper Sacramento River and tributaries so they can access historical spawning and rearing-habitat that has been inaccessible for decades since dam construction. This summer, DWR and CDFW will participate in an effort with multiple agencies, tribes, and interested parties to test a system intended to collect juvenile salmon as they make their way downstream – a critical component of the assisted migration process. This and other similar relocation projects are considered one of many ways to help ensure Central Valley salmon persist through the extended droughts predicted for California’s future.
- State, federal, and university scientists are working to uncover new information and develop further actions to support and protect California’s salmon. For the last two years, scientists have observed that many baby salmon are dying before they hatch or shortly after that, and discovered the cause was a thiamine deficiency in their parents resulting from a shift in the ocean food web, a phenomenon recently observed in several fish populations around the globe. While a simple thiamine bath has proven effective in alleviating this deficiency in hatchery fish, naturally spawning salmon in the rivers continue to be heavily impacted. Last spring, DWR and CDFW began thiamine treatments on the large number of adult spring-run salmon that pass through the Feather River Fish Hatchery but are released back into the river to spawn to help this already drought-stricken salmon population weather the period of altered ocean conditions.
For more information on the project, please visit the CDFW website.