Habitat-Specific Foraging by Striped Bass (Morone saxatilis) in the San Francisco Estuary, California: Implications for Tidal Restoration

University of California, Davis (UC Davis) | December 1st, 2022

Non-native predatory fish strongly affect aquatic communities, and anthropogenic habitat alterations can exacerbate their effects. Loss of natural habitat, and restorati

Non-native predatory fish strongly affect aquatic communities, and anthropogenic habitat alterations can exacerbate their effects. Loss of natural habitat, and restoration actions that reverse habitat loss, can modify relationships between non-native predators and prey. Predicting how these relationships will change is often difficult because insufficient information exists on the habitat-specific feeding ecology of non-native predators. To address this information gap, we examined diets of non-native Striped Bass (Morone saxatilis; 63 to 671 mm standard length; estimated age 1 to 5 yrs) in the San Francisco Estuary during spring and summer in three habitat types—marsh, shoal, and channel—with the marsh habitat type serving as a model for ongoing and future restoration. Based on a preyspecific index of relative importance, Striped Bass diets were dominated by macroinvertebrates in spring and summer (amphipods in spring, decapods and isopods in summer). In spring, diets were relatively consistent across habitats. In summer, marsh diets were dominated by sphaeromatid isopods and shoal/channel diets by idoteid amphipods and decapods. Striped Bass consumed a variety of native and non-native fishes, primarily Prickly Sculpin (Cottus asper) and Gobiidae. The highest importance of fish prey was in the marsh in spring (~ 40% prey weight), and fish prey comprised less than 25% prey weight in all other season/habitat combinations. Linear discriminant analyses suggested that marsh foraging was prevalent in Striped Bass collected in other habitats, mostly because of the predominance of marsh-associated invertebrates found in the stomachs of individual Striped Bass collected outside the marsh. Striped Bass diets differ across habitats, with marsh foraging important to Striped Bass regardless of collection location. This information can be used to forecast the potential utilization of restored habitats by this non-native piscivore.

Haven or Hazard: The Ecology and Future of the Salton Sea

Pacific Institute | February 1st, 1999

California’s Salton Sea is a fertile oasis in the hostile desert of south-eastern California. It has been adopted by millions of birds migrating along the Pacific Flywa

California’s Salton Sea is a fertile oasis in the hostile desert of south-eastern California. It has been adopted by millions of birds migrating along the Pacific Flyway and also attracts human anglers and boaters. Rehabilitating the Salton Sea presents a huge challenge to the local, state, and federal officials that share responsibility for its health, as well as the health of those in surrounding communities. Originally published in February 1999,  Haven or Hazard: The Ecology and Future of the Salton Sea looks in detail at the condition of the Sea, the threats to the area, and possible solutions to protect its value for animals and people.

Hazard’s Toll: The Costs of Inaction at the Salton Sea

Pacific Institute | September 3rd, 2014

The declining Salton Sea will impose massive public health and environmental costs on local residents and Californians generally, as described in the Pacific Institute re

The declining Salton Sea will impose massive public health and environmental costs on local residents and Californians generally, as described in the Pacific Institute report Hazard’s Toll. The continued failure to protect and preserve the Salton Sea, worsening air quality and the loss of valuable ecological habitat – combined with diminished recreational revenue and property devaluation – could cost as much as $70 billion over the next 30 years. The high costs of California’s 2007 plan for the Salton Sea have inhibited deliberation and deterred any meaningful investment in revitalizing the Salton Sea. Many decision-makers assume that delaying action at the Salton Sea will result in business as usual, with no additional costs. Hazard’s Toll makes clear that this is not the case. Because the Salton Sea has changed over the past decade and will soon enter a period of very rapid decline, the costs of inaction are escalating rapidly. Even at the low end of the costs estimated in Hazard’s Toll, the long-term social and economic costs of a deteriorating Salton Sea could approach $29 billion, well in excess of the project cost of the state’s plan. The consequences of continued inaction at the Salton Sea will be felt most directly by the 650,000 people who live in harm’s way of the Salton Sea’s dust, as well as by the birds and other life that depend on the lake. Hazard’s Toll estimates the costs of these consequences, for the first time. These considerable costs demonstrate the urgent need for action at the Salton Sea. The report also highlights a large number of important data gaps that should be addressed in the near future. Despite many decades of study and the impending decline of the Salton Sea, we still lack information on many factors affecting life and the economy in the region. These factors, combined with general uncertainty about population growth rates, climate change, and changing hydrologic conditions, suggest that the above estimates indicate a general magnitude of potential future costs, rather than precise projections.

Health of Native Riparian Vegetation and its Relation to Hydrologic Conditions along the Mojave River, Southern California

U.S. Geological Survey (USGS) | July 15th, 1999

Height-related changes in forest composition explain increasing tree mortality with height during an extreme drought

Nature Portfolio (Springer Nature) | July 7th, 2020

Recently, Stovall et al. showed that during an extreme drought, remotely sensed mortality of tall trees was more than double that of short trees. They interpreted this t

Recently, Stovall et al. showed that during an extreme drought, remotely sensed mortality of tall trees was more than double that of short trees. They interpreted this to be a consequence of inherently greater hydraulic vulnerability of tall trees, and suggested that tall-tree vulnerability should generalize more broadly. Here we reassess their conclusions using contemporaneous, ground-based data from near their study sites. We find that 90% of trees belong to taxonomic groups showing declining, not increasing, mortality with height, and that the overall increase in mortality with height is instead a consequence of height-related changes in forest composition, not intrinsically greater vulnerability of tall trees. Similar mechanisms likely explain mortality patterns at Stovall et al.’s sites, and, regardless, we show that their conclusions should not be accepted in the absence of robust tests of alternative mechanisms.

Hetch Hetchy Restoration Study

California Department of Water Resources (DWR) | July 17th, 2006

The restoration of Hetch Hetchy Valley on the upper Tuolumne River has once again captured the public’s imagination. In order to provide for an informed dialogue about

The restoration of Hetch Hetchy Valley on the upper Tuolumne River has once again captured the public’s imagination. In order to provide for an informed dialogue about this issue, the Resources Agency has objectively evaluated the many Hetch Hetchy Valley restoration studies produced during the past two decades. In so doing, the state also recognized the great value and benefit of providing a central clearinghouse of all Hetch Hetchy restoration work. Moreover, in conducting the study, the state provided a neutral, public forum to discuss issues related to Hetch Hetchy restoration, such as water supply and water quality, flood management, cultural resources, environmental impacts, energy generation, and recreation. In all, several hundred people participated in a July 2005 workshop in Sacramento and at other stakeholder meetings throughout the state. In addition, many interested Californians provided written comments for our consideration. This final report is a comprehensive analysis of Hetch Hetchy Valley restoration studies. But even as a comprehensive analysis, we find, first and foremost, that much study remains to be done because there are major gaps in vital information. For example, objectives for replacing the water supply for the Bay Area, dam removal methods and impacts, and considerations of the public use and benefit of a restored Valley remain largely undefined. Another critical, missing element is a formal public involvement process to engage agencies, Native American tribes, stakeholders and other interested parties in this issue. While we offer no formal recommendation about next steps, it is clear that further investigations into Hetch Hetchy Valley restoration cannot be led by the State of California alone. Federal participation will be important to help shape future studies and to work with the San Francisco Public Utilities Commission, tribes, and the public on any next steps in this process. Moving forward, the Resources Agency’s role in studies and planning for Hetch Hetchy will be consistent with the state’s approach to other significant natural resources such as the Sacramento-San Joaquin Delta or the Salton Sea — to protect the public trust by ensuring that these natural places are protected and utilized for the benefit of all Californians.

How freeing rivers can help California ease flood risks and revive ecosystems

Los Angeles Times | February 20th, 2024

Natural floodplains — the lush green lands along rivers that historically flooded, retained water, and nourished life in the heart of the valley — were mostly drained

Natural floodplains — the lush green lands along rivers that historically flooded, retained water, and nourished life in the heart of the valley — were mostly drained and converted to farmland generations ago as the state’s waters were dammed and diverted. Today, an effort to bring back some of those floodplains is flourishing at the 2,100-acre Dos Rios Ranch Preserve near Modesto, where workers years ago planted native trees on retired farm fields and removed berms to create space for water to spread out again.

Human contributions to evapotranspiration mitigate swings in dry-to-wet year transitions

Nature Portfolio (Springer Nature) | January 9th, 2026

California’s food and economic security depends on water availability, particularly under increasingly extreme climate scenarios. A key component of the water balance i

California’s food and economic security depends on water availability, particularly under increasingly extreme climate scenarios. A key component of the water balance is evapotranspiration, the combination of soil and surface evaporation and plant transpiration. Evapotranspiration is influenced by natural drivers (e.g., climate, vegetation cover) and human intervention (e.g., irrigation, land management). Here, we analyze the transition between one of California’s driest years (2022) to an exceptionally wet year (2023) to assess evapotranspiration responses to climate extremes. Despite increased precipitation, total statewide evapotranspiration changed less than 10%. In 2022, human contributions accounted for 30% of statewide evapotranspiration and 80% in managed lands. In 2023, natural evapotranspiration increased, and human contributions fell by 30%, yet still comprised nearly 50% of evapotranspiration in managed areas. Our findings underscore the enduring role of human activity on California’s hydrology, even during wet years, and demonstrate a framework to separate natural and anthropogenic controls on evapotranspiration.

Human Impacts Dominate Global Loss of Lake Ecosystem Resilience

American Geophysical Union (AGU) | June 5th, 2024

Human Use of Restored and Naturalized Delta Landscapes

University of California, Davis (UC Davis) | October 31st, 2016

Current legislation and state plans for the California Delta call for large-scale restoration of aquatic and terrestrial habitats, which will require significant changes

Current legislation and state plans for the California Delta call for large-scale restoration of aquatic and terrestrial habitats, which will require significant changes in land uses and cultural patterns to achieve. Yet landscapes that are restored for habitat for other-than human species will remain subject to human uses. This report looks at how human presence can and will continue after restoration, and considers how these uses can be best reconciled with cultural, ecological and adaptive management goals. Our one year study builds off other research projects that have explored the California Delta from an integrative human-environment perspective. It uses a landscape planning approach that attempts to push beyond single sectoral methods, seeking a holistic integration of multiple goals and land use agendas spanning across ecological, social, economic and political domains. This report’s findings are based on surveys, interviews, review of existing Delta planning literature, field work and specific landscape case studies. In general, our research supports the advancement of a reconciliation approach, which seeks synergies between ecosystem needs and the desires of those who live, work and play in the Delta, both now and in the future.