Science Spotlight

Salton Sea, Riverside and Imperial Counties.


Surface roughening at Salton Sea.


Monitoring equipment.


Dust suppression at Salton Sea.


Fishery biologists Sharon Keeney of CDFW (r) and Shauna Bishop of Barrett's Biological Surveys look for desert pupfish.

Stretching between Southern California’s Imperial and Coachella valleys, the Salton Sea is what one might call a landmark of untraditional beauty. At 33 miles long and 5 miles wide, it’s the state’s largest inland lake, serving a crucial role as a stopover for migratory birds using the Pacific Flyway.

But the Salton Sea lacks the conventional, inviting atmosphere of other lakes on the West Coast. Its waters are rapidly evaporating, leaving another few thousand acres of dry and dusty lakebed (playa) each year. That loss of water increases the lake’s already-high levels of salinity, and it occasionally emits a pungent rotten egg odor that permeates the air. And – of particular concern to scientists – the evaporation decreases habitat for the wildlife that has historically thrived in and around this important ecosystem.

“Since its formation, the Salton Sea has been fed by irrigation runoff in the Imperial and Coachella valleys and inflow from rivers,” explained CDFW’s Salton Sea Program Manager Gail Sevrens. “But water transfers and related agreements and measures have contributed to a reduced volume of runoff, and as the water evaporates, the Sea has lowered in elevation. This has led to a shrinking, saltier Sea, and those increased areas of exposed dry lakebed can emit dust, which is of concern to local communities.”

Sevrens oversees CDFW’s participation in the Salton Sea Management Program (SSMP), which seeks to address those concerns, both for the benefit of fish and wildlife and the humans that live in the valley. The SSMP is an effort between CDFW and the California Department of Water Resources, under the direction of the California Natural Resources Agency. The partners seek to implement projects that will slow the damage and aid in recovery, primarily through the construction of approximately 30,000 acres of habitat and dust suppression projects around the Sea.

The program has several priorities:

• Making significant, visible progress in getting restoration and dust suppression projects accomplished as part of its 10-Year Plan;
• Creating a long-term plan;
• Building the team; and
• Strengthening local partnerships.

Many Californians are unfamiliar with how the current Salton Sea came to existence – it’s not an exaggeration to call this an “accidental lake.” Though large seas have formed and dried here throughout history due to natural flooding from the Colorado River, the Salton Sea in its current iteration was born in 1905 when the Colorado River breached an irrigation canal being constructed in the Imperial Valley. The escaping water slowly filled a dry lakebed nearly 300 feet below sea level. At first, developers imagined the Sea as a popular lakeside resort. But it was not to last, as without a continued, reliable source of water supply, the lake’s waters could only evaporate, reducing conditions for wildlife and nearby residents. In fact, due to agricultural runoff and evaporation, the water in the Salton Sea is approximately twice as salty as ocean water.

This fall, work began on the nearly 4,000-acre Species Conservation Habitat (SCH) project. That work will create a series of ponds at the southern end of the Sea that will include nesting and roosting islands and areas of varying water depths to serve as fish and bird habitat. At its healthiest, the Salton Sea was host to a half dozen species of fish, while 400 species of birds visited the lake while traversing the Pacific Flyway.

The SSMP projects provide dust suppression benefits. For example, temporary dust suppression measures have been taken on the south side of the Sea at the SCH site, where, through a process called surface roughening, approximately 700 acres of land were manipulated to create ridges and furrows that are perpendicular to the prevailing wind direction. Additional dust suppression and habitat restoration projects are in development for areas of exposed dry lakebed around the Salton Sea.

According to CDFW Environmental Scientist Samantha Przeklasa, the seemingly simple approach of rearranging the ground can make an enormous difference. “When the wind comes across the surface-roughening furrows, they slow the wind and catch particulate matter in the air. That matter gets caught in the little furrows, in the low spots.

(Watch this video tour of the Salton Sea with Environmental Scientist Samantha Przeklasa)

Though habitat work is just beginning, scientists are seeing the benefits for one species already. Przeklasa praises fellow CDFW Environmental Scientist Sharon Keeney for her work finding, relocating and ultimately saving desert pupfish. The only native fish species at the Salton Sea, the tiny pupfish are found in shoreline pools, agricultural drains and natural creeks. Though pupfish can survive low levels of dissolved oxygen, high salinity and high water temperatures, they won’t survive in ponds and ditches that go dry. That’s where Keeney’s work has truly made a difference.

“There are many irrigation drains across the entire Salton Sea, on the north and south. Sharon spends a lot of her time monitoring those drains to see where the pupfish are thriving, and then rescues them from small drains that may be about to completely dry up,” said Przeklasa. “From a small pond, we can get hundreds, if not thousands, of fish out of it.” The fish are relocated to nearby ponds that are fed by natural desert springs, or managed ponds. Desert pupfish have also been relocated to ponds at a local high school, UC Riverside’s Palm Desert campus, and the Living Desert Zoo and Gardens in Palm Desert. The latter has even named one of its newest desert pupfish refuge ponds after Keeney.

Ultimately it will be engineering and habitat construction that helps the pupfish and other species survive. The work being done brings joy to program manager Sevrens, who was first attracted to the unusual beauty of the Salton Sea through documentaries. Her affection for the lake grew even further while bird-watching and occasionally kayaking there.

“A lot needs to go on behind the scenes before you can actually do a project, and we are moving forward on multiple project tracks at a time,” she said. “It’s exciting to see the pieces coming together.”

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Media Contact:
Tim Daly, CDFW Communications, (916) 201-2958

CDFW Photos

The California Fish and Wildlife Journal concludes the 2020 Special Issue installments with the winter quarter’s Special Wildland Fire Issue. With this year’s unprecedented fire season, and California’s fire-adapted natural communities taking center stage in land management discussions throughout the State and beyond, this issue is especially poignant as we reflect on this past year and contemplate the incoming new year.

Unlike previous Special Issues, this issue is divided into three sections: Vegetation Treatment and Policy, Fire Impacts on Plants, and Fire Impacts on Wildlife and Water. Each section highlights a piece of the wildfire and landscape management ‘puzzle’ through an examination of fire and its impacts on California’s fire-adapted ecological landscape.

One of these unique communities, the Pine Hill Ecological Reserve in El Dorado County, is home to almost 750 plant species, some of which can only be found at Pine Hill due to its unique soil composition. Researchers from CDFW, the California Native Plant Society and Sacramento City College investigate the impacts of different fuel-reduction methods on Pine Hill Ceanothus in “Effects of a firebreak on plants and wildlife at Pine Hill, a biodiversity hotspot, El Dorado County, California” (PDF). The article examines the effects of hand clearing and pile burning on chaparral species within the Wildland Urban Interface and the secondary impacts on wildlife. The study also includes the exciting discovery of new seedlings of Pine Hill Flannelbush, the rarest and most endangered plant in El Dorado county, and a fire-obligate germinator!

Plants that depend on fire to propagate aren’t the only plant communities impacted by the long-term fire suppression practiced in the western United States. New and updated technology is helping landscape managers and scientists study and assess the pre- and post-fire impacts to landscapes using remote sensing and modeling techniques. This type of data collection and analysis helps inform scientists and policy makers on landscape and watershed-level scales and helps focus efforts to manage habitats and sensitive plant communities before and after wildfires. One such effort is presented by Sonoma County scientists in “Sonoma County Complex Fires of 2017: Remote sensing data and modeling to support ecosystem and community resiliency” (PDF). With the help of NASA and other experts the team evaluates the impacts of the 2017 fires to woody vegetation within areas that burned during wind-driven and non-wind driven events to evaluate canopy condition. Using lidar data, the team identifies important predictors for post-fire woody canopy condition, which highlights the importance of high-resolution airborne mapping technology for informing management decisions.

Management decisions include when and how to monitor pre- and post-fire events, and the CSU Monterey Bay’s study “Analysis of the impacts of the Soberanes Wildlife on stream ecosystems” (PDF) highlights the need for monitoring wildfire’s impacts on coastal streams and benthic macroinvertebrate responses to fire events. This monitoring is especially important because macroinvertebrates are the foundation for in-stream salmon and steelhead foodwebs, and the ability of these microscopic organisms to recover from wildfire also impacts the recovery of these keystone species in California’s rivers and streams.

This quarter’s Special Wildlife Fire Issue also includes examinations of impacts and responses of Roosevelt Elk forage in Humboldt County, an essay on the California Vegetation Treatment Program, amphibian responses to wildfire and other topics that span California’s rich ecological diversity.

The California Fish and Wildlife scientific journal has published high-quality, peer-reviewed science that contributes to the understanding and conservation of California’s wildlife for more than 100 years. We look forward to the continued contributions in the next decade to come.

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Media Contact:
Kirsten Macintyre, CDFW Communications, (916) 804-1714

CDFW biologists and hatchery staff overcame several obstacles for a successful 2020 kokanee salmon egg collection effort on the Little Truckee River.


Kokanee salmon eggs are collected and fertilized streamside, as shown in this 2019 photo, before being taken to a CDFW hatchery for incubation.


A temporary weir is set up along the Little Truckee River to block, catch and spawn kokanee salmon that have migrated up from Stampede Reservoir as shown in this 2019 photo. Among other challenges in 2020, CDFW staff had to conduct the annual kokanee spawn without the help of volunteers due to COVID-19-related precautions.

In spite of challenges presented by wildfires, forest closures, unhealthy air quality and the COVID-19 pandemic, CDFW staff from the American River Trout Hatchery and Fisheries Branch nonetheless conducted four successful kokanee salmon egg collections on the Little Truckee River this fall.

Slightly more than 1.3 million eggs were collected from kokanee salmon migrating from Stampede Reservoir in Nevada County into the Little Truckee River to spawn. Stampede Reservoir’s kokanee salmon serve as CDFW’s broodstock for the popular State fishery.

CDFW typically relies on volunteers from the public and angling groups to help with the annual egg collection effort – but that extra manpower was unavailable this year due to COVID-19 precautions.

“This year was unique to say the least, but this was a high priority for us,” said Jason Julienne, senior environmental scientist supervisor for CDFW’s North Central Region hatcheries. “Many of the waters that support the kokanee fishery are not self-sustaining, and depend on annual releases to provide ample opportunity for anglers.”

Due to COVID-19 concerns, this year’s egg collection involved less staff than normal, which slowed the process a bit. Typically, the team can collect all the eggs needed to support the program in two to three days. This year, it took four days, and required extensive coordination with the U.S. Forest Service in order to get special access to closed areas of the Tahoe National Forest.

“Luckily, everything came together on time and we were able to get it done,” Julienne said. “We had 12 to 15 staff participating in each of the four egg collections, as well as two staffers who remained onsite for five weeks to maintain the fish barrier weir and monitor salmon numbers coming up the river.”

The collected eggs are now being incubated at CDFW’s San Joaquin Hatchery and American River Trout Hatchery. Once the fry reach about three inches in size, they will be stocked to support recreational fishing at 15 lakes and reservoirs throughout the state. About 850,000 kokanee fry are released annually.

Kokanee salmon (Oncorhynchus nerka) are the landlocked version of Sockeye salmon native to Alaska and the Pacific Northwest. Instead of migrating to the ocean, adult kokanee inhabit large lakes and impoundments before returning to their natal streams or using gravel shorelines to spawn. Like all Pacific salmon, kokanee die after spawning, their whole life cycle spanning two to four years.

Although they only average about 12 inches in size as adults, kokanee salmon are an exceptionally popular sport fish noted for their excellent table fare. As the kokanee fishery has thrived, bag and possession limits have been increased at several lakes and reservoirs in recent years, including at Lake Pardee in Amador County, New Bullard’s Bar Reservoir in Yuba County and Trinity Lake in Trinity County.

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Media Contact:
Peter Tira, CDFW Communications, (916) 215-3858

CDFW Photos

The fall 2020 issue of California Fish and Wildlife (PDF), CDFW’s quarterly scientific journal, features a series of scientific articles on the environmental impacts associated with legal and unpermitted commercial cannabis cultivation. Once primarily hidden deep in the forests of the Emerald Triangle, cannabis cultivation activities are now occurring all over California.

Like other forms of commercial agriculture, land use practices associated with cannabis agriculture can pose a serious risk to many threatened and endangered species. Elijah Portugal and Jason Hwan, CDFW scientists, explore the environmental impacts with an article titled “Applied Science to Inform Management Efforts for Cannabis Cultivation, Humboldt County, California” (PDF). The piece focuses on the preliminary findings of a study examining the impacts of cannabis cultivation on private lands in and near remote, forested watersheds of northwestern California. This area has supported decades of illegal cultivation and today, includes both legal and illegal cannabis grows in the same watershed.

The State Water Resources Control Board’s Cannabis Cultivation Program reviews observations from the field in a part of the state that has not been historically reported on with a piece titled “Two Years After Legalization: Implementing the Cannabis Cultivation Policy in Southern Coastal California” (PDF). Some of the initial findings indicate that ninety four percent of the 519 enrollees in the Cannabis General Order are discharging their industrial wastewater to publicly owned treatment plants, while the remaining enrollees haul their industrial wastewater to a permitted wastewater treatment facility. Along with this, the unit has also supported state and county enforcement efforts and inspected numerous illegal cultivation sites and observed activities that could be detrimental to water quality and numerous fish and wildlife species.

Researchers from the University of California, Berkeley and CDFW present a piece titled “Coexisting with Cannabis: Wildlife Response to Marijuana Cultivation in the Klamath-Siskiyou Ecoregion" (PDF), which examines local wildlife community dynamics on and nearby active private-land cannabis farms. Using camera data collected between 2018–2019, scientists monitored numerous wildlife species within the Klamath-Siskiyou Ecoregion in southern Oregon. The results suggest that cannabis farms were generally occupied by smaller-bodied wildlife species, and had a higher proportion of domestic dogs, cats and human activity as compared to nearby comparison sites. They conclude that wildlife will likely have species-specific responses to cannabis cultivation and suggest the need for educational resources on wildlife-friendly growing practices.

Learn more about other cannabis research studies in this issue and what scientists are learning, including reviews of the potential impacts of pesticides, artificial light, noise pollution and trash.

For over 100 years, the California Fish and Wildlife scientific journal continues to publish high-quality, peer-reviewed science that contributes to the understanding and conservation of California’s wildlife. We look forward to the contributions of the next installment.

Media Contact:
Janice Mackey, CDFW Communications, (916) 207-7891

Unarmored threespine stickleback


CDFW staff capture UTS from a drying pool in Fish Creek. Click to enlarge


UTS removed from minnow traps in Fish Creek. Click to enlarge


Jennifer Pareti releases UTS into Soledad Canyon Creek. Click to enlarge


UTS released in Soledad Canyon Creek. Click to enlarge

Of the many large wildfires that destroyed millions of acres around California during the 2020, one blaze in particular threatened to wipe out years of fishery conservation efforts. The Lake Fire in Los Angeles County burned more 31 thousand acres and it illustrated – for the second time in four years – what lengths dedicated biologists will go to in order to preserve California’s Unarmored Three Spine Stickleback (UTS). The UTS, Gasterosteus aculeatus williamsoni, is a state and federally listed endangered species and a State of California Fully Protected Species.

The story of this rescue actually began in 2016 when a different fire – the Sand Fire – left multiple feet of sediment settling into Soledad Canyon Creek. CDFW fisheries biologists jumped into action to manually rescue about 150 UTS. The biologists transported the fish to a CDFW hatchery, where they remained for about six months while biologists planned the next move back to the wild. Fish Creek, near Castaic Lake, was selected as an appropriate spot for the relocation, and the biologists were right. The transplanted UTS have been breeding and doing well in that body of water for the last several years.

That’s until part two of this story presented itself. When the Lake Fire presented a new possibility of sediment flow into Fish Creek, the biologists again had to take action. This time, about 300 fish were collected and moved again – this time, in a sense, returning back home.

“When the Lake Fire came across, we watched in horror as the whole upper watershed burned,” said CDFW Inland Fisheries Senior Environmental Scientist John O’Brien. “We knew the situation would be dire as soon as we started getting storms this winter. Once we saw the estimations of the sediment that would come down in the system, it was clear we should take some action. We reached out to our federal partners who co-manage the species with us and we all agreed the best thing to do would be to take some of the fish – as many as we could reasonably get in one day – and bring them back to Soledad, where they came from originally. That habitat has recovered quite nicely (since 2016), so the timing was good.”

O’Brien credited the successful effort to CDFW environmental scientists Jennifer Pareti (the project lead), Russell Barabe and Matt Lucero, as well as scientific aides Marissa Groenof, Mike Stephens, Karen Boortz, Austin Sturkie and Thompson Banez.

“We used minnow traps to trap the UTS, and because we’ve had high heat over the past couple of weeks, we used nets to get them out of small, isolated pools that were drying back,” said Pareti. Like her boss, Pareti was instantly worried about the fisheries impacts when the fire began.

“Honestly, you see these fires start and you watch them take off, and we can only sit on the sidelines (while it’s happening),” she said. “Once the fire is under control, we can get in and start doing the next set of work. We have to look at what we can we do to help the resources. How can we help the fish perpetuate through this giant hurdle that’s ahead?”

Even though it was the same species of fish being moved each time into and then out of Soledad Canyon, it wasn’t literally the same fish. “They’re an annual species, which means they only live about a year,” Pareti explained. “Some of them might live into their second year, but the fish we moved are a generation or two removed from the first batch that was moved in 2016.”

Knowing they’ve helped a species that’s struggled to keep itself going brings great satisfaction to O’Brien and his staff.

“Because of the emergency situation of this fire, we weren’t able to do a really robust and thorough count, but we estimate that we took about 70 percent of the fish that were there,” O’Brien said. “They (UTS) are, along with the Southern California steelhead, the most endangered fish we have in Southern California. Those fish species are literally on the edge of being able to continue to exist. Whenever there’s a threat to a UTS population, we take it very seriously,” said O’Brien.

The team plans to continue to monitor the waters for the UTS – not just those at Soledad Canyon Creek, but also Fish Creek, which will recover from the fire damage naturally over time. “Maybe some of those fish (we didn’t capture) will survive,” said Pareti. “Ideally, that stream will provide a long-term opportunity for this species so we can help to expand the population.”

To learn more about UTS, please visit the CDFW website.

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Media Contact:
Tim Daly, CDFW Communications, (916) 201-2958

CDFW photos