A Fishmas Carol: Ghosts of Salmons’ Pasts

by Kelly Neal

Figure 1: Artistic rendering by Mark Clark of California from space during the 1850s. Source: Big Think

Here is a story not quite like the one you have heard before, but echoes a similar tune as traditional lore. California salmon are at a precipice with conservation attempting to mitigate threats of climate change, habitat loss, and genetic simplification. Yet today, we have the knowledge and tools to create a future for California’s salmon.

All California native fishes are tied to the region’s unique hydrology. Over evolutionary time, our salmon have diversified in return run timing, egg hatching, and juvenile stage seaward migration to create the Central Valley Chinook Salmon complex (Herbold et al. 2018, Figure 1). This bet-hedging strategy results in an ecological “portfolio effect” for salmon species that minimizes boom-bust cycles in population dynamics (Carlson et al. 2011). This evolutionary strategy worked well for long periods, even during huge historic mega-droughts and massive floods.

Figure 2: Life-cycles of Central Valley salmon with and steelhead, highlighting that salmonids are inside the freshwater environment all year. This life-history variation spreads extinction risk and brings resilience to salmon overall through a portfolio effect. Source: CH2M Hill for the California Rice Promotion Board

Salmon in California were historically so abundant that they sustained entire Nations of Native Americans for the whole year, and there were supposedly so many fish that one could walk across rivers without touching water, only the tops of returning salmon adults (Smithsonian Magazine 2008). Native Americans traditionally viewed salmon as immortal; each annual cycle brought spectacular mass death scenes of salmon in rivers, yet the following year, rivers would again be filled with thousands more returning fish. Tribes would ritually place bones of each season’s harvest back in the river to safeguard this cyclic phenomenon. Catches of salmon along the California coast by commercial fishers in the late 1800s often would overwhelm local canneries. These tales, not unlike those my own grandpa would tell me, only scratch the surface of the historic ecological and cultural connection of salmon to California waterways. This is the ghost of salmon’s past, and it is a haunting reminder of how quick such magnificent feats of nature can be lost.

Figure 2: Hydraulic mining in the foothills of the Sierra Nevada in the 1870s. Source: USGS

Now we face the ghost of salmon’s present: the aftermath of rapid, exploitative Western expansion in California. People often think of miners panning for gold when they think of the gold rush, but intense extraction methods such as dredging entire riverbeds and hydraulic mining washing down entire moutainsides fundamentally altered river channel composition and quality downstream. These extraction methods washed ~64 million cubic yards of sediment into the largest estuary on the west coast: the San Francisco Bay Delta (Department of the Interior, 1917). This estimate doesn’t account for immense loads of sediment deposited upstream, infilling channels and critical floodplain habitat. With mining came the commencement of dam building, which quickly blocked access to major salmon spawning habitat at all scales. Decades of overfishing, worsening climate change, and habitat simplification, have remade a landscape mismatched to that salmon have spent thousands of years evolving within.

Rapid human modifications have quickly led to the present and greatly diminished state of California salmon runs; runs genetically simplified and worsening as time progresses. Runs were so low in both 2008 and 2009, that commercial salmon fishing was banned off the coast of California, and runs that once numbered in the millions now struggle to reach baseline stock replacement. This year in Butte Creek, a record 10 degree increase in water temperatures amid spawning habitat caused a mass mortality event: of the approximate 16,000 Spring-run salmon that returned to the creek, at least 14,500 died before they could spawn. For a field research project, my field partner (Matt Salvador) and I quickly discovered this fall that simply acquiring enough salmon carcass tissue samples would be a challenge because of the low numbers. Despite the stunning and photogenic landscape around us, I was saddened how multiple trips were needed to find any signs of carcasses. During years with decent snowpack and manageable summer temperatures, this river is typically full of bodies from successful Spring-run spawners.

Figure 4: Butte Creek in October 2021, lacking carcasses in the warm waters. Source: Kelly Neal

Not all is lost for California salmon, as many reconciliation efforts are afoot by researchers, environmental organizations, government agencies, tribes, and landowners. Reintroduction efforts of spring-run Chinook salmon into the San Joaquin River have shown promise: in 2019 for the first time in 65 years, adult salmon have returned to the San Joaquin River to spawn. Collaboration between farmers, ecologists, and nonprofits that comprise the ‘Nigiri Project’ have been working over the past decade to demonstrate a potential for winter-flooded rice fields to provide rearing habitat for juvenile salmon. In Putah Creek, there is increasing evidence that runs of salmon might be recovered by hatchery strays, provided salmon habitats are thoughtfully rehabilitated.

As in the traditional tale, the ghost of salmon’s future is ambiguous. We are at a crossroads in California salmon conservation. Though we recognize salmon will not return entirely as they once did, the hope is to create a future where salmon and human civilization can co-exist, and perhaps even thrive. Much science, management and freshwater habitat conservation is needed to achieve this, as future projections highlight that native California salmon cannot persist with current operations (Moyle et al. 2017). A resilient California salmon future will require sacrifices and immense work by all Californians, as we all depend upon the water that salmon so desperately need. We have been acting like Ebenezer Scrooge, unwilling to make the difficult choices needed to protect vulnerable salmon populations out of inconvenience and greed.

To what extent new tools and science can combat effects of future droughts, warming oceans, and already simplified genetic portfolios remains to be seen. What is certain is that salmon, and the incredible ecosystems and services they support, will perish without substantial protection efforts. Conservation efforts must accelerate, and be supported by policy to ensure a future that includes California salmon. Salmon play an integral role in the California landscape, ecologically, culturally, and commercially, and should remain so in the future. I still have hope for these incredible fish – creatures that have one of the most complex and fascinating life cycles known. This collective hope rests on the shoulders of all Californians, whom I implore to find ways they can to support a future with California salmon in it.

Kelly Neal is a Junior Specialist researcher at the Center for Watershed Sciences working on projects related to Central valley Chinook salmon conservation.

Figure 5: Jumping among a school of spring run Chinook salmon in a cold water refugia pool in Butte Creek, spring 2021. Source: Carson Jeffres

Further Reading



Carlson, S.M., and W.H. Satterthwaite. 2011. Weakened portfolio effect in a collapsed salmon population complexCanadian Journal of Fisheries and Aquatic Sciences 68: 1579-1589.

Herbold, B., S.M. Carlson, R. Henery, R.C. Johnson, N. Mantua, M. McClure, P. Moyle, and T. Sommer. 2018. Managing for salmon resilience in California’s variable and changing climateSan Francisco Estuary and Watershed Science 16(2).

Moyle, P.B., R. Lusardi, and P. Samuel. 2017. SOS II: Fish in hot water. Status, threats and solutions for California salmon, steelhead and trout. 

About andrewrypel

Andrew Rypel is an Associate Professor and the Peter B. Moyle and California Trout Chair of coldwater fish ecology at the University of California, Davis. He is a faculty member in the Department of Wildlife, Fish & Conservation Biology and Co-Director of the Center for Watershed Sciences.
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