By Ted Sommer and Jeffrey Mount

Introduction

The conservation of freshwater biodiversity has emerged as a global challenge. The loss of habitat and the changing climate are reducing the viability of native freshwater species worldwide—and California is no exception to this. For decades the state has struggled to protect its native species.  Today, roughly half of California’s native freshwater plants and animals are vulnerable to extinction by the end of this century (Howard et al. 2015; Moyle et al 2022).  Rapid changes in climate are making it harder to conserve these species.  

Californians have shown an enduring commitment to protecting native species. Numerous efforts are underway to meet that challenge.  All Californians benefit when their freshwater ecosystems—meadows, streams, lakes, rivers, floodplains, wetlands, marshlands, estuaries—are healthy enough to support multiple human uses as well as biodiversity. But rapid changes in climate, along with historic land and water uses, are making it increasingly likely that many native species will disappear, and new, less-desirable ecosystems will appear.  Urgent action is needed. 

In this California WaterBlog post, we summarize a recent PPIC report that describes innovations that will help the state protect native biodiversity under climate change. We propose the adoption of climate-smart conservation frameworks and tools in all efforts to protect and restore native species. This includes utilizing a portfolio of actions—some controversial and experimental—along with a willingness to take risks. We hope that this report inspires scientists, engineers, resource managers, decision makers, watershed groups, and many others to take urgent action before we lose our legacy of freshwater biodiversity.

Climate-Smart Conservation Frameworks

The traditional approach to species conservation often focuses on protecting or restoring critical habitat for listed species. This is where existing laws, enacted more than 50 years ago, have the greatest leverage. But with limited exceptions, efforts are concentrated on a few regulatory levers—especially flows—and they do not explicitly address the rapid changes currently underway, much less actions necessary to adapt to these changes. And less than 6% of the species identified as vulnerable to extinction this century are currently protected by Endangered Species Acts (based on data in Howard et al. 2015).  

We propose a shift in strategy. Climate change adaptation should be explicit in all facets of freshwater ecosystem and biodiversity management. And where possible, the focus should shift away from listed species and toward native biodiversity and ecosystem health as the primary objective. 

In our review of the literature on this subject, we found that the National Wildlife Federation’s Climate-Smart Conservation Framework (Stein et al. 2014) offers a helpful way to organize climate adaptation plans and guide actions during their implementation. This kind of framework can and should be incorporated at all levels, including statewide efforts like the California Salmon Strategy; regulatory efforts such as Species Recovery Plans, Biological Opinions, and Water Quality Control Plans; and ongoing watershed-scale conservation planning throughout the state. 

A Portfolio Approach to Climate-Smart Conservation

In many freshwater conservation efforts, the choice of actions tends to be narrow, often reflecting regulatory agencies’ perceived authority (e.g., addressing only flow and water quality through regulation). Given the pace and geographic complexity of climate change, and uncertainties over ecosystem response, it is essential that a full range of tools be considered in climate-smart conservation. And given the urgency of the need for response, all options should be on the table, including emerging tools that are experimental or controversial.  

Through a series of workshops with experts, we developed a suite of strategies and tools that can populate a portfolio of climate-smart conservation actions. We identified 17 different tools that fall into two general management strategies: habitat support, including actions to improve the abundance and quality of habitat; and species support, including actions to improve the abundance and genetic diversity of vulnerable species. We also recognize that natural selection and human intervention may be insufficient to prevent extirpation and extinction of some species. For this reason, we propose five contingency actions as a parallel strategy to habitat and species support. Table 1 summarizes the strategies and tools and provides real-world case examples currently in use in California. The technical appendix to our report describes these strategies and actions in detail, and gives additional examples. 

Habitat support tools expand the amount and quality of habitat necessary to support native biodiversity. These are the most-used tools in conservation management and are most likely to have ecosystem benefits. Our toolbox therefore highlights many of the traditional approaches such as flow and substrate improvements, greater food production, habitat diversity and function, and temperature and water quality improvements. But we also describe much more experimental approaches such as the use of different technologies for applications such as non-native species control. 

Species support tools go beyond habitat improvements and focus more narrowly on specific taxa. For many native species, multiple factors—including low population size, extensive habitat loss, and the rapid pace of climate change—make it difficult to rebuild population size and diversity, leading to a high likelihood of extirpation or extinction without these types of intervention. Species support falls into three general categories: 

• Distribution support promotes the reconnection of species to sources of shelter, food, and opportunities for reproduction, as well as maintaining genetic diversity.  This includes not just helping species move past barriers, such as dams, but also the controversial practice of translocating species outside of their historic range. 
• Population support involves interventions to bolster population size. This includes reducing sources of mortality (i.e., restrictions on harvest, excessive predation, loss of species at water diversions), disease remediation, and population supplementation through hatcheries. 
• Genetic support seeks to take advantage of existing genetic diversity or to introduce more genetic diversity into populations to aid their adaptation to changing conditions. Many existing strategies, such as habitat support and distribution support, play an important role in maintaining genetic diversity and resilience, but additional tools—many highly controversial—may be needed when populations become genetically homogenous or numbers are low. Genetic support includes protecting genetic diversity (particularly of wild species) by reforming hatchery practices and locations, as well as some of the most experimental conservation tools: selective breeding in hatcheries, epigenetics and the introduction of new genes; and promoting hybridization to improve resilience.  

Contingency actions should be an integral part of the climate-smart conservation portfolio given the high likelihood of extirpation and extinctions of some species. These actions include filling in the numerous gaps in knowledge about native species before they are lost (e.g. diets, behaviors, physiology, habitats), along with tissue archives, genetic libraries, and seed banks. Contingency actions also include planning for the loss of some species and the new mix of native and non-native species that will be supported by changed or even novel ecosystems.  

Contingency actions are rarely discussed by the conservation community or by fish and wildlife managers because it implies “giving up.” We do not view it this way, since contingency actions also provide critical information for conservation needed to avoid extinction. In a worst-case scenario, they also create the possibility of future reintroductions of species.  But we also need to develop contingency management plans for future novel ecosystems, where the current regulatory focus on listed species may become irrelevant due to extirpation or extinction.

Conclusion

Climate change is happening faster than scientists predicted.  The year 2023 was the warmest in recorded human history and it appears that 2024 will be as well. The pace of change, along with poor existing habitat conditions in many California watersheds, is speeding the decline in native biodiversity. Time is running out to “bend the curve of biodiversity loss” and there needs to be a greater sense of urgency to act. 

Despite these dire statistics, we were encouraged to find many real-world examples of conservation innovations that could be used to develop climate-smart portfolios. And there is strong support for tackling the impacts of climate change at all levels of government. But California may not have the luxury of taking years to make new adaptation plans. We therefore recommend that while planning for the future, it is also important to act now by implementing pilot programs, experimenting with many of the tools outlined here, and immediately starting a statewide historic conservation program for freshwater species, including tissue archives, genetic libraries, and seed banks. We need to act like we are running out of time—because we are. 

Ted Sommer is a PPIC Caltrout Fellow at the Public Policy Institute of California.  He was previously Lead Scientist for California Department of Water Resources, where he worked on statewide water issues for over three decades.  He has published extensively on California native fishes, food webs, rivers, estuaries, floodplain, tidal marsh, invasive species, and hydrology.

Jeffrey Mount is a senior fellow with the Water Policy Center at the Public Policy Institute of California. He is an emeritus professor of Earth and Planetary Sciences at UC Davis and Founding Director of the Center for Watershed Sciences. He is a fluvial geomorphologist by trade.

Table 1. Management Toolbox for Climate-Smart Portfolios

Additional Reading

Grantham, T., J. Mount, S. Yarnell, and E.D. Stein. 2020. Making the Most of Water for the Environment: A Functional Flows Approach for California’s Rivers. Public Policy Institute of California.

Howard, J., K. Klausmeyer, K. Fesenmyer, J. Furnish, T. Gardali, T. Grantham, et al. 2015. “Patterns of Freshwater Species Richness, Endemism, and Vulnerability in California.” PLoS ONE 10(7).

Mount, J., Brian Gray, Karrigan Bork, James Cloern, Frank Davis, Ted Grantham, Letitia Grenier, Jennifer Harder, Yusuke Kuwayama, Peter Moyle, Mark Schwartz, Alison Whipple, and Sarah Yarnell. 2019. A Path Forward for California’s Freshwater Ecosystems. Public Policy Institute of California.

Moyle, P., A. Sturrock, and J. Mount. 2022. Technical Appendix A: California’s Freshwater Fishes: Conservation Status, Impacts of Dams, and Vulnerability to Climate Change in Storing Water for the Environment. Public Policy Institute of California.

Null, Sarah, Jeffrey Mount, Brian Gray, Kristen Dybala, Gokce Sencan, Anna Sturrock, Barton “Buzz” Thompson, and Harrison “HB” Zeff.  2022.  Storing Water for the Environment.  Public Policy Institute of California. 

Sommer, Ted, Jeffrey Mount, Brian Gray, Letitia Grenier, Jennifer Harder, and Gokce Sencan. 2024.  Climate-Smart Tools to Protect California’s Freshwater Biodiversity.  Public Policy Institute of California. 

Stein, B.A., P. Glick, N. Edelson, and A. Staudt. 2014. Climate-Smart Conservation: Putting Adaptation Principles into Practice. National Wildlife Federation, Washington, D.C.