Salmon: A Keystone Species of the Yuba River 

Why These Iconic Fish Matter More Than You Might Think 

What Is a Keystone Species And Why It Matters 

In every ecosystem, species are connected through intricate relationships — predators and prey, pollinators and plants, decomposers and the dead. While many of these species play essential roles, some exert a disproportionately large influence compared to their population numbers. These are known as keystone species. 

A keystone species is like the central stone in a traditional stone arch. Remove that stone, and the entire structure collapses. In an ecosystem, removing a keystone species can trigger a domino effect, disrupting food webs, changing habitat, and even altering the physical landscape. Keystone species help regulate populations, maintain biodiversity, and support ecosystem resilience. 

Keystone species can take many forms. Apex predators like wolves keep herbivore populations in check, preventing overgrazing. In coastal ecosystems, sea otters are a classic example; when they were overharvested for their pelts, sea urchin populations exploded, leading to overgrazing of kelp and the collapse of entire kelp forest ecosystems. This is a textbook case of a trophic cascade, showing how the loss of a single keystone species can ripple through an entire food web. Even small organisms, like certain types of bees, are keystone species because they pollinate a wide variety of plants essential to an ecosystem’s health. 

What all keystone species have in common is that their presence is critical to balance. When they thrive, ecosystems flourish. When they disappear, ecosystems unravel. 

This concept is more than a metaphor, it’s observable across biomes, from tropical rainforests to alpine rivers. And here in Northern California, few keystone species are as ecologically significant — or as culturally iconic — as salmon. 

Why Salmon Are a Keystone Species 

Salmon are more than just iconic fish; they are ecological powerhouses. These anadromous species (meaning they migrate from the ocean to freshwater to spawn) connect distant ecosystems. When salmon return from the ocean to spawn in freshwater streams, they bring with them marine-derived nutrients that fertilize entire watersheds. 

After spawning, adult salmon die, and their bodies become food for birds, bears, otters, and other wildlife. Their decaying carcasses also enrich the soil and feed insects, which, in turn, support birds, fish, and amphibians. Even trees benefit; scientists find ocean-derived nitrogen from salmon in the rings of riverside trees everywhere salmon historically swam, evidence of a deep and ancient relationship between salmon and forests.

Salmon and the Yuba River 

The Yuba River once supported one of the most abundant runs of Chinook salmon in the Sierra Nevada. For thousands of years, these fish made the long journey from the Pacific Ocean to the upper reaches of the Yuba to spawn, nourishing the river ecosystem and sustaining Native peoples. Salmon were the beating heart of the watershed, returning year after year in a life-giving cycle that connected ocean, mountain, wildlife, and human communities. 

Today, that cycle is deeply disrupted. 

Daguerre Point Dam, a century-old structure on the lower Yuba River, hinders salmon from accessing upstream spawning habitat. While fish ladders exist, they are ineffective for many salmon, especially during times of high or low flows. Just upstream, Englebright Dam is a complete barrier to migration, with no fish passage whatsoever, keeping this keystone species from 80% of its historic spawning habitat. These structures prevent salmon from reaching the cold, clean, gravel-rich tributaries where they could successfully reproduce. 

But the problems go beyond physical barriers. Water temperature is a critical factor in salmon survival. Salmon need cold, oxygen-rich water to thrive. As climate change intensifies and Sierra snowpack declines, the Yuba’s summer water temperatures are increasing, and do not match the temperature regime salmon evolved with.  Warm water can be lethal for salmon eggs and juveniles, and even adult salmon may fail to spawn if the water is too warm. 

SYRCL’s River Science team, in partnership with state and federal agencies, conducts year-round water quality and habitat monitoring on the Yuba. Our data show that summer water temperatures in the lower Yuba River have approached or exceeded the upper thermal limits for salmon survival, particularly during prolonged drought years.  

Altered flow regimes caused by upstream dams and diversions also pose a major threat. Natural flow patterns — high, cold spring pulses from snowmelt followed by lower flows in summer — are essential cues for salmon migration and spawning. However, the Yuba’s flows are now regulated largely to meet hydroelectric and agricultural demands, not ecological needs. These altered flow regimes can strand young fish, disrupt spawning, and reduce access to side channels that provide critical rearing habitat. 

Finally, climate change compounds these threats. With less snowpack, more intense droughts, and increasing wildfire risk, the Yuba River ecosystem is under growing stress. Salmon are highly sensitive to environmental change and with every degree of warming, their chances of survival diminish. Spring-run Chinook salmon in the Yuba River are at high risk of local extinction within the next 50 years if current warming and water management trends continue. 

Yet, despite these challenges, salmon continue to return to the Yuba. Their resilience is remarkable. But without meaningful restoration, protection, and action, these ancient migrations may disappear within our lifetimes. 

SYRCL’s Strategy for Salmon Recovery 

At SYRCL, we believe that the return of healthy salmon runs to the Yuba River is possible, but it will take a bold, science-based, and community-driven effort to get there. 

For over two decades, SYRCL has been a leading voice in salmon restoration in the Yuba watershed. Our strategy is rooted in collaboration, advocacy, and cutting-edge ecological science. Here’s how we’re working to bring salmon back: 

• Restoring Habitat: SYRCL leads projects to reconnect floodplains and restore side channels that provide critical spawning and rearing habitat. One of our flagship efforts is the restoration of the Lower Long Bar, a nearly 50-acre project site designed to increase high-quality habitat for juvenile salmon during key life stages. 
• Monitoring Fish Populations: Our River Science team closely monitors spawning and rearing activity at our restoration sites using tools like snorkel surveys, PIT tagging, capture-mark-recapture studies, redd counts, and temperature loggers. This data is essential for understanding where salmon are struggling and where they’re still holding on. 
• Fighting for Fish Passage: SYRCL is actively advocating to improve volitional fish passage for all native species to upstream habitat. We work with local, state, and federal partners to develop fish-friendly alternatives that balance ecological needs with human infrastructure. 
• Influencing Water Policy: We engage in regulatory and legal processes that determine how water is managed in the Yuba watershed. SYRCL pushes for water flows that are more aligned with natural patterns to benefit salmon migration and reproduction. 
• Addressing Climate Resilience: We incorporate climate science into all our restoration efforts to ensure long-term success. From advocating for cold-water releases to designing climate-adapted habitats, SYRCL is preparing the Yuba River for a warming future. 
• Educating and Empowering the Public: Through our Salmon Expeditions, community science initiatives, Wild & Scenic Film Festival school program, and restoration tours, we’re raising awareness and building a movement for salmon and river protection. 

What You Can Do: Be a Voice for Salmon 

The return of wild salmon to the upper Yuba River is not just a dream, it’s a vision of hope, resilience, and renewal. But it won’t happen without people like you. 

Here’s how you can take action today: 

• Support policy change: Stay informed about local water issues and raise your voice at public hearings, comment periods, and community meetings. We’ll help you know when and how to speak up. 
• Donate to fuel our work: Your contribution helps us fund science, advocacy, and restoration projects that directly support salmon recovery. 
• Attend a SYRCL event: Whether it’s a public Salmon Expedition, the State of the Yuba event, a Wild & Scenic film screening, or our annual Yuba River Cleanup, our events are a great way to connect with others who care. 

Together, we can restore a river that works for fish, forests, and future generations. The salmon are still coming back. Let’s make sure the Yuba is ready for them. 

Be part of the return. Be part of the movement. Be a SYRCL member.