SCIENCE NEWS: Adventures in Bay-Delta data; Survival of migrating juvenile salmon depends on stream flow thresholds; Effects of artificial lighting on salmon survival; Steelhead workshop summary now available; and more …

Science Stories: Adventures in Bay-Delta data

One of life’s greatest joys is playing with data. However, not everyone has the time or experience needed to make fancy graphs. Fortunately, availability of on-line web applications that allow people with no data analysis experience to visualize status and trends of data across space and time has exploded in recent years.  One of the first data visualization tools was the mapping widgets on the CDFW website. These maps allow you to plot the catch for different fish species as different size bubbles, and have been available since the late 1990s ... ”  Read more from the IEP blog here:  Science Stories: Adventures in Bay-Delta data

Survival of migrating juvenile salmon depends on stream flow thresholds

Juvenile salmon migrating to the sea in the Sacramento River face a gauntlet of hazards in an environment drastically modified by humans, especially with respect to historical patterns of stream flow. Many studies have shown that survival rates of juvenile salmon improve as the amount of water flowing downstream increases, but “more is better” is not a useful guideline for agencies managing competing demands for the available water.  Now fisheries scientists have identified key thresholds in the relationship between stream flow and salmon survival that can serve as actionable targets for managing water resources in the Sacramento River. The new analysis, published May 19 in Ecosphere, revealed nonlinear effects in the flow-survival relationship, meaning it changes in stepwise fashion, with significant jumps in survival rates at two key steps. ... ”  Read more from UC Santa Cruz here:  Survival of migrating juvenile salmon depends on stream flow thresholds

Effects of artificial lighting on salmon survival

As a favorite snack of many predatory species, a Chinook salmon (Oncorhynchus tshawytscha) smolt’s best chance at survival is to sneak by undetected. One key adaptation is their tendency to migrate at night concealed by darkness. However, the Sacramento-San Joaquin Delta of today is very different from that traversed by Chinook a century ago. Contemporary estimates of survival rates for salmon passing through the Delta are as low as 5%, and this is thought to be a major reason for declines in Central Valley Chinook populations. Human alterations such as introducing invasive predatory fish, spreading exotic aquatic vegetation, and leveeing the Delta’s waterways have caused dramatic changes to the ecosystem, but one factor that has received less attention is our penchant for lighting up the night, which may literally be shining a spotlight on beleaguered Chinook salmon smolts. … ”  Read more from FishBio here:  Effects of artificial lighting on salmon survival

Trending downward: California’s 2020 salmon season

It’s time for our annual summary of the Pacific Fishery Management Council (PFMC) Review of Ocean Salmon Fisheries. After surprisingly high returns in 2019, the California Chinook salmon population in 2020 failed to meet expectations (although was still larger than the depressed population levels seen following the recent drought). Each year, the PFMC publishes a report on the previous year’s salmon fisheries along the West Coast. The report details harvest totals and socioeconomic benefits for the California ocean fishery, as well as escapement totals, or the number of salmon that “escaped” the fishery and returned to the Central Valley. The report also provides an opportunity to compare these numbers with the preseason prediction that was used to set harvest regulations for that year. … ”  Read more from FishBio here:  Trending downward: California’s 2020 salmon season

Steelhead workshop summary now available

The Delta Science Program hosted the Monitoring Steelhead Populations in the San Joaquin Basin Workshop, February 17-19, 2021.  At the workshop participants reviewed the management challenges and monitoring framework for Oncorhynchus mykiss and explored analytical approaches to measure the impact of management actions on San Joaquin Basin steelhead.  Key takeaways from the discussion centered on needs related to sampling methodology, access, funding, coordination, and data and analysis. Suggested management actions included the establishment of clear benchmarks, development of hypotheses and conceptual models, synthesis of existing conditions, and the enhancement of monitoring with an emphasis on data prioritization.”  Read the report at the Delta Stewardship Council website here: Steelhead Workshop Summary

CalTrout sponsors the 2021 Virtual Salmonid Restoration Conference

Established as a scientific leader on fish and water issues in the state, CalTrout roots its projects in research to drive innovative, science-based solutions to the state’s resource issues.  In April 2021, CalTrout sponsored and presented at the 2021 Virtual Salmonid Restoration Federation (SRF) Conference. The annual Salmonid Restoration Federation Conference offers an unparalleled opportunity for professionals, academics, and scientists to present their research to a large audience of fisheries restoration enthusiasts.  The SOS II: Fish in Hot Water Report was a staple reference during the conference. Researchers continue to look to this publication as the pinnacle, in-depth report detailing the status of California’s 32 native salmon, steelhead and trout. This report also guides our 5 Key Initiatives, strategies that guide our on-the ground-restoration including: Protect The Best, Reconnect Habitat, Integrate Wild Fish and Working Landscapes, Steward Source Water Areas, and Restore Estuaries.  Several CalTrout researchers presented at the 2021 SRF conference speaking on topics from dam removal to fish food webs. … ” Check out the recordings and description of the talks from Cal Trout here:  CalTrout sponsors the 2021 Virtual Salmonid Restoration Conference

Smelt Science at the 11th Bay-Delta Science Conference

During the 11th Bay-Delta Science Conference held virtually from April 6-9, one session focused on studies of delta (Hypomesus transpacificus) and longfin smelt (Spirinchus thaleichthys), two tiny fish species that are vital components of the food web and indicators of ecosystem health. Conserving and recovering their declining populations requires understanding how smelt respond to changing environmental conditions, and developing models to evaluate the efficacy of monitoring and management actions. The conference’s Smelt Science session highlighted a need to reconsider the current ecological understanding of these species, as well as new tools to help inform management and recovery actions. … ”  Read more from FishBio here: Smelt Science at the 11th Bay-Delta Science Conference

Studies find sierra fuel treatments benefit trees and streamflow, though not together

Predicting the effects of forest fuel treatments is difficult and uncertain — it is unclear whether the treatments are more helpful to forest health or streamflow. According to new research by disturbance ecohydrologist Ryan Bart and his colleagues at the Sierra Nevada Research Institute (SNRI), the answer is both, though not at the same time.  Fuel treatments for forest management include prescribed burns, tree thinning and pruning, for example, each of which are done to reduce fire risk and severity. Bart recently conducted two studies to examine the effect of these fuel treatments in the Sierra Nevada on both the streamflow in rivers and overall forest health of the trees.  “The focus of these two papers was trying to understand how and when water made available from fuel treatments is allocated to forest health and/or streamflow,” Bart said. “Many studies have investigated these issues separately, but they have rarely been examined in tandem. This is important because fuel treatments cannot provide full hydrologic benefits to both forest health and streamflow simultaneously. They can be allocated to forest health or to streamflow, or partially to both.” … ”  Read more from UC Merced here: Studies find sierra fuel treatments benefit trees and streamflow, though not together

Long-term monitoring shows successful restoration of mining-polluted streams

Many miles of streams and rivers in the United States and elsewhere are polluted by toxic metals in acidic runoff draining from abandoned mining sites, and major investments have been made to clean up acid mine drainage at some sites. A new study based on long-term monitoring data from four sites in the western United States shows that cleanup efforts can allow affected streams to recover to near natural conditions within 10 to 15 years after the start of abatement work.  The four mining-impacted watersheds—located in mountain mining regions of California, Colorado, Idaho, and Montana—were all designated as Superfund sites under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), which helps fund the cleanup of toxic-waste sites in the United States. … ”  Read more from UC Santa Cruz here: Long-term monitoring shows successful restoration of mining-polluted streams

Salamander sleuthing: Turning over rocks helps conservation efforts of secretive species

On a chilly, rainy day in Northern California, a 3-inch-long web-footed salamander crawls out of a rock crevice, its sticky toes clinging to an outcrop on a forested slope. While most cold-blooded animals are dormant in cooler weather, several species of salamanders are the exception to this amphibian ‘rule’ and actually require these conditions to become active above ground.  Ranging from Shasta Lake to the Klamath-Siskiyou Mountains of northern California and southern Oregon, the Shasta, Siskiyou Mountains and Scott Bar salamanders live similar lifestyles. All of these salamanders are lungless, needing moist conditions to breathe through their skin. They spend both cold winters and hot, dry summers hiding under logs, deep within rock crevices, or inside limestone or other rocky caves. They only become active above ground most often at night during short periods in the late fall and spring, and during the winter when temperatures are above freezing, and humidity is high.  For these thin, nimble amphibians, their choice of living quarters is ideal. ... ”  Continue reading at the US Fish and Wildlife Service here:  Salamander sleuthing: Turning over rocks helps conservation efforts of secretive species

What to do with fish when the river runs dry

” ... Salmon cross barriers that other animals can’t, transforming physiologically as they move between fresh and salt water and back again on a mind-blowingly epic migration. Yet these evolutionary feats are not serving them well in the modern age. Since European contact, a third of the 1,400 distinct salmon populations along the west coast have gone extinct. Dams and development hinder migrations. Overfishing in the oceans and rivers cuts into population numbers, too. Now this resilient silver fish is facing a new, possibly insurmountable challenge. A warming climate is drying and disconnecting waterways they’ve traveled for millennia. As far as we know, a salmon has no evolutionary trick for surviving a dried puddle.  This has led salvagers, like Bernhardt, to make a last-ditch effort to keep a run alive. The practice is mostly ad hoc and volunteer-run, with government agencies giving implicit permission by practicing it themselves. A few wildlife agencies on the west coast of the United States have run fish salvages since the 1950s, like the California Department of Fish and Wildlife’s network of concrete collection facilities and fleet of oxygenated trucks that move endangered fish around water pumps in the Sacramento-San Joaquin River delta. As the climate warms and threatens freshwater habitat, more governments will likely adopt the practice.  Normally, this might be a success story, except no one really knows if salvage succeeds. Is a salvaged fish truly saved? … ”  Read more from Hakai Magazine here: What to do with fish when the river runs dry

The bright side of the green crab

The first thing to know about the green crab is that it isn’t necessarily green. Fresh out of the ocean in southwestern Nova Scotia, it can appear brown, or red, or yellow. What is distinctive is its spiked shell that tapers at the top into 13 spines, like a crown worn by the leader of an invading army—which is appropriate enough, since the second thing you need to know about the green crab is that it’s one of the planet’s most aggressive invasive species.  In its path toward world domination, the European green crab—which, as the name suggests, originally hails from Europe, as well as North Africa—has acquired a lot of titles: “cockroach of the sea” and “one of the 10 most unwanted species in the world.” In Nova Scotia, fisherman Jeff Roy has come up with his own moniker.  “I’ve nicknamed them sea ticks, because they’re just as lively,” he says. “They’ll give you quite a bite, too, when they grab ahold of you.” … ”  Continue reading at Hakai Magazine here: The bright side of the green crab

Restoration efforts can brighten an ecosystem’s future, but cannot erase its past

An expansive project led by Michigan State University’s Lars Brudvig is examining the benefits, and limits, of environmental restoration on developed land after humans are done with it.  Experts estimate there are up to 17 million square miles of land worldwide that have been altered by humans — through cultivation say — and then abandoned. That’s more than four times the size of the continental United States. Once humans change a landscape, their impacts linger long after they’ve moved on. However, humans can heal some of that damage by working to restore the land to its natural state. … ”  Read more from Science Daily here: Restoration efforts can brighten an ecosystem’s future, but cannot erase its past

Missing the middle: the importance of regional-scale field research

Hundreds of biological field stations exist across the globe, supporting highly local, single-site projects as well as endeavors spanning continents. Yet few are networked on a regional scale. Likewise, current funding structures do not support regional science research over the long term. These omissions hamstring efforts to understand the climate crisis and its impacts plants and animals.  According to a new paper in the journal BioScience, regional field studies are the Goldilocks of climate change ecology: just right for examining the impacts of the climate crisis on plants and animals. “Many of these questions can only be answered at an intermediate, regional scale. That’s the scale that is really important to organisms and their populations, because they involve dispersal and evolution,” says coauthor Laurel Fox, a professor of ecology and evolutionary biology at UC Santa Cruz. … ”  Read more from UC Santa Cruz here:  Missing the middle: the importance of regional-scale field research

Slow research to understand fast change

In a world that’s changing fast, the Long Term Ecological Research (LTER) Network can seem almost an anachronism. Yet the patience and persistence that have generated 40 years of careful, reliable science about the Earth’s changing ecosystems may prove to be just what’s needed in this rapidly shifting world. We can’t wait for a crystal ball — and we don’t have to. By harnessing decades of rich data, scientists are beginning to forecast future conditions and plan ways to manage, mitigate, or adapt to likely changes in ecosystems that will impact human economies, health and wellbeing.  The National Science Foundation established the LTER Network more than 40 years ago to provide an alternative to funding models that favored constant innovation over continuity. The model has proven to be extraordinarily successful at both.  This month, in the Ecological Society of America’s open-access journal Ecosphere, LTER researchers present examples of how changing populations — of fish, herbs, trees, kelp, birds and more — both reflect and influence the structure and resilience of ecosystems. … ”  Read more from the Ecological Society of America here: Slow research to understand fast change

Maven’s XKCD Comic Pick of the Week …



About Science News and Reports: This weekly feature, posted every Thursday, is a collection of the latest scientific research and reports with a focus on relevant issues to the Delta and to California water, although other issues such as climate change are sometimes included. Do you have an item to be included here? Submissions of relevant research and other materials is welcome. Email Maven

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