Rewilding Baby Salmon Using Indigenous Knowledge

The Winnemem Wintu Tribe and fish biologists have designed a groundbreaking salmon egg incubator that mimics the conditions of California’s McCloud River.

In July 2022, the Winnemem Wintu Tribe as well as several fish and wildlife agencies celebrated the reintroduction of Chinook salmon to the McCloud River in far Northern California for the first time since World War II. That was when federal officials removed Winnemem Wintu people from their ancestral homes along the river and erected the 602-foot Shasta Dam, blocking the salmon’s migration path and flooding 27 miles of the lower McCloud.

salmon incubator on McCloud River

Winnemem Wintu hereditary Chief and spiritual leader Caleen Sisk uses an “aquascope” to examine how the salmon fry and newly hatched salmon are doing inside the hatching boxes of the incubation system the Tribe developed. Photo by Marc Dadigan.

Because mother salmon couldn’t swim up the river to dig their nests, called redds, agency staff trucked and helicoptered fertilized salmon eggs from a Sacramento River hatchery to the remote, mountainous site on the McCloud River. They then deposited the eggs into streamside incubators, which are designed to imprint the unhatched salmon with an urgent desire to return to the river’s unique water chemistry as adults. After experimenting with a barrel-like incubator, agency staff eventually moved the eggs to another device called “heath trays” because they could filter the McCloud’s potentially dangerous spouts of turbid flows.

All of this was part of an urgent effort to save California’s winter-run Chinook from extinction. After struggling for decades, the winter-run Chinook eggs suffered catastrophic death rates in the summers of 2021 and 2022 when drought and industrial diversions turned the Sacramento River into a sizzling death trap.

The glacial McCloud River water, the winter-run salmon eggs’ potential refuge, is piped and cascaded continuously through the heath trays, which resemble four tall stacks of eight enclosed dishwashing tubs stationed upright on the riverbank. While the incubator keeps the eggs cold and protects them from predators, the Winnemem Wintu’s Hereditary Chief and Spiritual Leader Caleen Sisk said she was horrified when she saw between 5,000 to 7,000 recently hatched salmon, known as fry, inside the heath trays.

In the wild, Sisk says, fry would be swimming in and around the rocks of the nest before leaving to explore the river. But inside the heath trays, hundreds of salmon were crammed together, laying sideways on top of one other without the space to move about.

“I didn’t like seeing them wiggle in there like a can of worms,” Sisk said. “I felt those salmon are going to have problems connecting and bonding with their home.”

Sisk also worried whether the juveniles would be fit enough to re-adapt to the McCloud. In 2009 federal scientists concluded the McCloud River’s frigid waters could be the endangered winter-run salmon’s best chance to survive the cascading impacts of climate change. But the river’s mountainous terrain, rapids, and flows laden with volcanic sediment are far different from hatchery raceways and the warm Sacramento River valley where salmon have spawned since the dam was constructed.

Even though the heath trays hatch salmon eggs at extremely high rates, up to 96 percent, the Winnemem Wintu Tribe, who are co-managers on the reintroduction, decided to develop their own incubator for this past summer, the second year of the project. For Sisk, the objective was not to hatch as many eggs as possible but to rear young salmon who more resemble resilient wild fish and are ready for life in the McCloud River.

Working in close consultation with the Tribe and using a hand-scribbled design by Sisk as inspiration, a team of UC-Davis fish biologists brought Sisk’s vision to life, constructing a groundbreaking system that mimics the McCloud’s river flows, rocks, and plant life. The incubator also allows young fish more time to practice swimming against swirling currents. And, rather than being released into the river en masse, the Winnemem Wintu’s baby salmon choose of their own volition when to leave the nest and enter the McCloud’s frigid flows.

The system, which the Tribe is referring to unofficially as the Nur Nature-Based incubator (Nur is the Winnemem Wintu word for salmon), hatched an estimated 40,000-plus eggs this summer and fall. While state biologists also hatched salmon eggs in heath trays this year, the general consensus based on anecdotal observations is that the Nur Nature-Based incubator appears to have nurtured young salmon that are healthy, strong, and well prepared for life in a free flowing river. More study is needed to truly evaluate the system, officials say, but the design of the incubator itself is an example of how, when Indigenous knowledge is respected, Tribes and Western scientists can collaborate to create important innovations that address the global decline of biodiversity and support local adaptation to climate change.

Dennis Coacherell, a UC-Davis fish biologist who led the construction of the incubator, said working with Sisk and the Tribe was a motivating experience of breaking down barriers between scientists and communities impacted by their research.

“Working hand-in-hand with the community to bring back a fish back to them, using our expertise with theirs, that is really the idealized version of what I want to do as a scientist,” he said.

Sisk noted that Winnemem Wintu Traditional Knowledge fills gaps in the scientific understanding of salmon, especially on the McCloud River which was bereft of the fish before contemporary scientists could ever study them. “[Western science] is missing information about the salmon life cycle and the importance of [the baby salmon’s] relationship to the river,” Sisk said. “This has been a new experience for scientists to be listening to me, to be excited to follow Winnemem Wintu knowledge.”

California's McCloud River

The McCloud River, which is fed by underground springs and glacier snowmelt from Mount Shasta, may be the last hope for endangered winter-run Chinook salmon to survive the cascading impacts of climate change. It is also the ancestral watershed of the Winnemem Wintu Tribe. Photo by Marc Dadigan.

Winnemem Wintu fishery staff

Winnemem Wintu fishery staff pose by the Nur Nature-Based incubation system. The hatching boxes are covered with sticks and leaves to provide shade for the fish and discourage birds and other predators. In the background, the state’s heath trays are visible. Photo by Marc Dadigan.

In the Tribe’s incubation system, the fertilized eggs are placed in one of three hatching boxes, which are lined with specially chosen rocks and plant medicines from the river. Using long pipes, gravity-fed water from more than 100 feet upriver is delivered into the system through long piping and sprayed in different directions across the boxes. This clears the eggs of sediment and, after they hatch, gives the baby salmon practice swimming in a complex flow environment, akin to that of the river.

When the young salmon are ready, they can traverse a little channel that cascades down into a circular tank, about four feet wide, which provides more space for swimming practice with swirling flows. From there, they can eventually swim down yet another waterslide-like channel into the river, where they’re protected in a small holding pool the Tribe constructed with large river rocks. A little opening in the corner of the pool provides a doorway for the fish to enter the wild river system when they’re ready.

Prior to their removal from the region, generations upon generations of Winnemem Wintu people constructed these holding pools up and down the McCloud as refuges for young salmon from predators and rapids, Sisk said. It’s one example of the myriad ways Winnemem Wintu people historically stewarded the once abundant McCloud River salmon runs and cultivated their deep, holistic knowledge of salmon. It was this ancestral knowledge that fueled the Tribe’s desire to create a new kind of incubator.

“These fish, in order to be wild, they have to have those relationships with the rocks [in the nest]. We know there’s a magnetism that develops between them and the rocks that gives them the drive to come back to that place as adults,” Sisk said. “The salmon also know what food and [plant] medicines are in the river to help them gain strength and gain protection against pathogens.”

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Surprisingly, many of the salmon fry have chosen to stay for several months in the Tribe’s incubation system, lingering in their pseudo-river nursery long after the state officials released their heath tray siblings into the river.

On an October visit to the site, located on a remote campground, Sisk and her staff marveled as the salmon fry in the holding pools demonstrated the elusive swimming skills that will help them evade predators. When any of them came within 15 feet of the pool, the baby salmon would immediately dart away for cover under a leafy tree branch floating on the surface.

“Any bug or food that flies onto a leaf, they’ll be able to see it from the water and jump for it. They also are ready to protect themselves from birds that fly overhead and other predators,” Sisk said.

For Chief Sisk, the Tribe’s incubator is an important manifestation of the Winnemem Wintu understanding of salmon as ancient and wise entities who carry knowledge, memory, and ecological responsibilities. Sisk said the salmon “know what to do” to restore their runs and enhance the watershed’s ecosystem if they’re protected from habitat degradation and liberated from scientific manipulation.

In recent years, the state has heavily invested in what are called nature-based solutions to climate change, and some fish biologists working on the project say the Tribe’s salmon knowledge dovetails perfectly with this new approach.

“I like working in this space where Chief Sisk has such clarity about recovering these animals by listening to what the fish tell us they need and understanding the river is the best home,” said Rachel Johnson, a federal fish biologist. “If we can’t put them in the river, making the artificial space more like the river will prepare them to be stronger.”

While the Nur Nature-Based incubator represents a successful implementation of their traditional knowledge, Sisk is adamant that the Tribe needs to regain land on their river to restore their role as the original McCloud River salmon stewards. After nearly 80 years of Shasta Dam-induced dispossession, the co-management agreement has made the Tribe’s dreams of a Winnemem Wintu-led McCloud fishery seem tantalizingly closer. The Tribe is seriously investigating how to regain land on the McCloud, focusing on the Bollibokka Club, owned by the Westlands Water District, and the US Forest Service land where the salmon reintroduction project is taking place. Currently known as Ah Di Nah campground, the Forest Service land is the site of the Winnemem Wintu’s ancestral village Way El Porhamas, a place where the Tribe’s ancestors carried migrating salmon in baskets over impassable barriers, Sisk said.

“You can’t separate the Indigenous knowledge from the land and the river. Our knowledge goes back to creation. Our language, our sacred places, our dances, our history and our relationships are all tied together with the McCloud salmon,” Sisk said.

The Tribe is also advocating for the construction of a swimway around Shasta Dam using augmented natural creeks to allow the salmon to migrate to and from the ocean. The alternative is to trap and truck them around the dam, which has had mixed results on other rivers and deprives the salmon of an important developmental experience, Sisk said.

And they are advocating for the reintroduction of Chinook salmon from New Zealand, where salmon runs were originally established by shipments of salmon eggs from a federal hatchery on the McCloud River. Because those salmon have been migrating in the mountainous, braided rivers in New Zealand with minimal interventions from hatcheries, the Tribe argues they have retained more of the wild and resilient character of their McCloud River ancestors.

“There is strength in the wild salmon,” Sisk said. “Like us, Indigenous people, they have the knowledge of the way it should be.”

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