Science Spotlight

  • June 20, 2022
Tanker truck used to transport fish.

CDFW staff with tanker truck used to transport smolts

Sportfishing boat on San Francisco Bay.
The Salty Lady sportfishing boat hosted Richmond youth

Smolts being released into bay through pipe.
Smolts being released into Richmond Harbor

Image of pipe used to transport fish from tanker truck.

Scientist on top of tanker truck.

Fall-run Chinook salmon smolt.
Fall-run Chinook salmon smolt

Moments after the sun set on Richmond Harbor’s Brickyard Cove on June 19, CDFW and its partners released approximately 200,000 hatchery raised juvenile fall-run Chinook salmon (known as smolts) into the bay.

The release was part of a larger effort to truck approximately 19.7 million fall-run Chinook salmon to locations in the San Francisco Bay, San Pablo Bay and lower portions of the Sacramento-San Joaquin Delta. CDFW has two more smolt releases planned for the week of June 20. Since beginning the effort in mid-April, staff have completed three to six releases per week.

Sunday night’s release was a collaboration with the City of Richmond, Golden State Salmon Association and Richmond Police Athletic League. The team invited a group of young people from Richmond to watch the release from a 56-foot sportfishing boat called The Salty Lady, the use of which was donated for the event to offer youth a glimpse into fishery operations.

“These kids definitely got a unique opportunity and a front row seat to watch this release,” said Senior Environmental Scientist Jason Julienne, supervisor over CDFW’s North Central Region hatcheries. “I hope it gets them interested and excited for fish and fishing, with the hopes of catching one of these fish when they return as adults in a few years.”

The goal of the releases is to improve survival of the salmon smolts by helping them bypass 50 to100 miles of hazardous river conditions caused by three consecutive years of drought in the Central Valley. CDFW fisheries biologists tracked flows and water temperatures in the fish's usual migration corridors and recognized that survival would be a challenge without intervention.

“We want to help ensure some of these fish survive to contribute to commercial and recreations fisheries, as well as hatchery and natural area production in the coming years,” said Julienne.

The smolts, raised at CDFW’s Feather River Fish Hatchery in Oroville, were eight to 10 months old when released. At that age, the smolts are developmentally ready to handle the salinity of bay waters. The Brickyard Cove location in Richmond was chosen because of its favorable tides and proximity to deep waters.

“We try to use outgoing tidal movements and the cover of darkness to help get these fish oriented in the right direction toward the Pacific Ocean, and reduce predation,” said Julienne.

All fish from yesterday’s release were marked and implanted with coded wire tags so CDFW can track their returns and determine how they contribute to fisheries and production in coming years.

For more information read CDFW’s news release on the trucking operation.


Categories: Science Spotlight
  • June 3, 2022
Crystal Lake Hatchery Manager Tim Baker shows off a plump Eagle Lake rainbow trout prior to spawning.

Crystal Lake Hatchery Manager Tim Baker shows off a plump Eagle Lake rainbow trout prior to spawning lakeside this spring.

CDFW crews electrofish Eagle Lake to capture rainbow trout for spawning.

Eagle Lake rainbow trout
CDFW crews electrofish the shores of Eagle Lake to gather the rainbow trout needed for spawning.

For the third consecutive spring, fisheries biologists with the California Department of Fish and Wildlife (CDFW) have slowly trolled the mineral-rich waters of Eagle Lake in Lassen County in electrofishing boats, netting the stunned, sizeable rainbow trout that float to the surface.

Their progeny will help ensure the future of this unique native species and will support CDFW’s trout stocking efforts statewide. Eagle Lake rainbow trout (Oncorhynchus mykiss aquilarum) are the only trout species capable of surviving in Eagle Lake’s high alkaline, high pH waters. The subspecies of rainbow trout does especially well when stocked into less harsh environments throughout the state.

Spring electrofishing is becoming a new normal at Eagle Lake amid reoccurring drought and climate change. Dropping lake levels and low water flows have prevented the Eagle Lake rainbow trout from accessing their primary spawning grounds in the Pine Creek tributary and forced fisheries biologists to modify annual spawning activities.

CDFW has had to largely abandon its fish trap and egg collection station at Pine Creek, which in wet, snowy years feeds into the northwest sector of the huge lake, the second largest natural lake in California. Instead, for the past three springs, CDFW has set up a makeshift spawning facility lakeside at the Gallatin Marina, the one accessible boat launch left from which to launch CDFW’s electrofishing boats.

The lower 25 miles of Pine Creek is a seasonal stream with intermittent flows, part of the reason CDFW first established a fish trap and egg collection station there in the 1950s to help perpetuate a rainbow trout subspecies endemic to Eagle Lake.

Commercial fishing in the late 1800s and early 1900s combined with the diversion of Eagle Lake water for agricultural use and overall environmental degradation in the early part of the 20th century caused Eagle Lake’s rainbow trout population to plummet and spurred the need for human intervention.

Drought conditions and climate change in the 21st century are the latest challenges impacting the rainbow trout and their ability to access Pine Creek and spawn naturally.

The lower stretch of Pine Creek has had insufficient flows to accommodate spawning five times in the past 10 years. There was a striking absence of snow on the shores, roads and mountains surrounding the lake this spring when CDFW’s spawning operations took place.

In April, CDFW conducted a fish rescue in Pine Creek, removing more than 100 rainbow trout and combining the fish with those collected by the electrofishing efforts. All the fish were returned to Eagle Lake immediately after spawning.

During the course of its six-week spawning season, CDFW collected more than 1 million eggs and spawned 380 pairs of trout. The eggs were fertilized lakeside at Gallatin Marina and taken to CDFW’s Crystal Lake Hatchery in eastern Shasta County. Genetic diversity was carefully cataloged and maintained by spawning different year classes of fish on a one-fish-to-one-fish basis. Each year class of hatchery reared fish is identified by a distinguishing and different fin clip.

Of those offspring, 180,000 trout eventually will be returned to Eagle Lake in 2023 to support the destination sport fishery there.

The remainder of those eggs and trout will be distributed far and wide in one fashion or another – some as eggs shipped to other CDFW hatcheries, some of those as trout planted for recreational fishing, others raised and kept as broodstock in yet other CDFW hatcheries. Eagle Lake rainbow trout are stocked into 305 bodies of water in 48 counties for recreational fishing in places as diverse as McCoy Flat Reservoir in Lassen County and Chollas Lake Park in San Diego County.

“You put these fish anywhere else in less harsh conditions and they do really well,” explained Paul Divine, CDFW’s district fisheries biologist for Modoc and Lassen counties who has overseen spawning at Eagle Lake since 2008. “That’s another thing that makes them ideal for our hatchery program. You can pretty much plant them anywhere. They also live longer than a typical rainbow. We’ve seen fish in the 7- to 8-year-old class. The oldest one we’ve documented was 11 years old.”

The 1 million eggs collected this spring, however, means fewer Eagle Lake rainbow trout overall. In normal, non-drought years, CDFW is able to collect 1.5 to 2 million eggs from its Pine Creek facility.

Eagle Lake rainbow trout are one of 10 species of native trout that qualify for CDFW’s Heritage Trout Challenge, which recognizes anglers who catch California’s native trout in their historic watersheds.

Eagle Lake itself is rather unique in that it only supports native fish. The lake’s inhospitable waters have doomed the introductions of 11 different non-native species between 1879 and 1956, including largemouth bass, lake trout and catfish.

Within those waters, the Eagle Lake rainbow trout is joined by three species of native minnows and one native sucker – the Eagle Lake Tui Chub, speckled dace, Lahontan redside and the Tahoe sucker.

Eagle Lake opened to fishing May 28, 2022. Fishing will remain open through the last day in February 2023. Anglers are limited to two trout per day and four in possession with no special gear restrictions.

“They are super fun to catch. They are a great fighting fish,” said Divine. “And I don’t think you could find a better fish to put on the table. They are excellent to eat.”

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

Categories: Science Spotlight
  • April 22, 2022
3 black bears in a transportation trailer.

Triplets released in Mariposa County

A black bear in a transportation trailer.
Plumas County release

Four orphaned bears were released back into the wild last week after spending the past six months at a wildlife rehabilitation facility in San Diego.

Three of the bears—triplets—were released back to national forest land in Mariposa County on April 14 just a few miles from where they were found last fall, when a bear presumed to be their mother was found shot dead nearby. The fourth bear, rescued from the Dixie Fire last year, was returned on April 15 to its home range in Plumas County. The black bears were born in winter 2020 and are now yearlings.

“We released them as far as we could from human-occupied areas to give them the best chance at living in the wild,” said CDFW biologist Mark Abraham, who coordinated the Mariposa County release. CDFW biologists George Harse and Tim Kroeker were also on the Mariposa County release team.

The bears were fitted with GPS collars which will track their movements and provide data that CDFW can use to inform wildlife management decisions.

“We hope to get useful data from the collars about where they go and what they do,” said Harse. “We’re curious to see how long the triplets stay together before going off on their own. Once bears disperse, they typically don’t hang out with family members.”

Black bears in California stay with their mothers for up to two years while learning to forage and survive. All four bears released last week were orphaned as cubs and didn’t have the opportunity to fully learn those skills. Since last fall the bears have been receiving care at San Diego Humane Society’s Ramona Wildlife Center.

CDFW Biologist Stacy Anderson, who coordinated the Plumas County release, was cautiously optimistic that the bears would succeed in their return to the wild.

“The cubs from Plumas County were brought in due to devastating impacts from the 2021 Dixie Fire. After receiving medical treatment and acquiring ample fat reserves they are now good candidates for release back to their native habitat,” said Anderson. CDFW biologist Sara Holm was also part of the Plumas County release team.

The public can report bear concerns to local law enforcement or to CDFW through its Wildlife Incident Reporting system. Public safety concerns should immediately be reported to law enforcement.

If you see a bear or bear cub, do not approach it. Adult bears, when out foraging, may leave offspring at a safe location for up to a day at a time. Seeing a bear cub by itself does not indicate that it is an orphan or that intervention is necessary.

For more information visit CDFW’s Keep Me Wild page on black bears:

Media contact:
Ken Paglia, CDFW communications

Categories: Science Spotlight
  • April 15, 2022
puma cub on trail

Photo by Kristen Perry, Midpeninsula Regional Open Space District

An orphaned, severely underweight mountain lion cub was rescued by CDFW on Sunday, April 10, and taken to the Oakland Zoo where it is currently receiving treatment.

The cub was first spotted on April 5 by a hiker on a trail in Thornewood Open Space Preserve near Woodside in San Mateo County. The hiker took a photo of the cub from a safe location and shared it with staff at Midpeninsula Regional Open Space District (MidPen), which manages the preserve.

Scientists were unsure if the cub’s mother was still in the area and began monitoring trail cameras to gather information. On Friday, they received a photo of the cub lying down on the trail near where it was seen before.

Veterinarians at CDFW’s Wildlife Health Lab saw the photo and immediately knew that the cub was malnourished and likely an orphan.

A CDFW team composed of biologists Garrett Allen and Megan Senour and wildlife officer Max Holland responded but did not initially find the cub. MidPen staff continued monitoring cameras throughout the weekend. CDFW wildlife officer Gabrielle Stauffer also joined the response team.

On Sunday, the team received a phone call from MidPen saying they found the cub lying down near the same location. CDFW returned to the trail and this time the cub was still there. Senour approached the cub with a catchpole while Allen and officers stood by as backup. Senour was able to walk right up to the cub and secure it. The puma was placed in a safe enclosure and transported to the Oakland Zoo.

“The cub was aware of its surroundings but either didn’t have the strength to run from us or didn’t want to try. It was easier to capture than we expected, which goes to show how rough of shape it was in,” said Allen.

The female cub is estimated to be about four months old. She was covered in fleas and ticks and weighed less than half the normal bodyweight of a healthy cub her age. The Oakland Zoo has a full veterinary staff and is treating the lion with plenty of fluids and nutrients to give it the best shot at recovering.

CDFW senior veterinarian Dr. Deana Clifford noted that the department typically takes a measured approach to wildlife interventions.

“It’s usually best to keep wildlife wild, but we do occasionally see situations where intervention is warranted. When these situations occur, we have great strategic partners like our colleagues at the Oakland Zoo and Midpeninsula Regional Open Space District,” said Clifford.

The public can report mountain lion sightings to CDFW through its Wildlife Incident Reporting system. Public safety concerns should immediately be reported to local law enforcement.

In urban areas throughout California, there are multiple threats to mountain lions including car strikes, toxins and illegal take. The Santa Cruz mountains offer suitable puma habitat including in parts of San Mateo, Santa Clara and Santa Cruz counties. However, it’s rare to see a mountain lion because they are elusive creatures.

“If you do see a mountain lion, do not approach it. Adult pumas, when out hunting prey, may leave offspring somewhere safe for up to days at a time. Seeing a young animal by itself does not indicate that it is an orphan or that intervention is necessary,” said Allen.

CDFW greatly appreciates the time that staff at MidPen spent assisting with the effort. From checking cameras daily to searching for and locating the cub on Sunday, the capture would not have been successful without their assistance. Although the kitten was in critical condition when rescued, it is responding well to veterinary care at the Oakland Zoo, and staff are cautiously optimistic she will make a full recovery, although she is likely to stay in captivity.

Wildlife Incident Reporting System:
Mountain Lions in California:

Categories: Science Spotlight
  • March 30, 2022
Close up of a young, healthy looking gray fox after rehab efforts

Fox finishing out rehabilitation and being prepped for release at Sierra Wildlife Rescue. Photo © Jackie Young

Anesthetized fox with burned paws lying on an exam table, with burned paws showing
Injured fox at Sierra Wildlife Rescue being prepped for initial debriding and cleaning of injured paws. Photo © Sierra Wildlife Rescue
Close up of a young gray fox with singed fur and whiskers, being held by a person
Injured fox shortly after being removed from under a porch in Pollock Pines. Photo © Sierra Wildlife Rescue

Each year, Californians filing their individual state income taxes can choose to donate money from their refunds or payments to the California Department of Fish and Wildlife’s (CDFW) Native Wildlife Rehabilitation Fund, line 403 on state tax form 540. Money from this Fund is then distributed through a CDFW competitive grants program that helps California rehab facilities support activities such as veterinarian treatment, animal care, facility maintenance and conservation education.

Sierra Wildlife Rescue (SWR) rehab facility in El Dorado County is a recipient of this funding, and recently helped a young, badly burned and injured California gray fox (kit) recover and be released back into the wild.

The kit was discovered hiding under the porch of a home in Pollack Pines on Sept. 6, 2021, after its residents returned from being evacuated from the Caldor Fire. The kit was estimated to be three to four months old, emaciated, burned and had extreme damage to its paws. 

“It took three days for our team to get the fox out from under the porch,” said Debbie Buckles, board president of SWR. “Once we got it out, we could see that not only was she singed, but she lost ear tips, and her feet were basically burned to the bone.”

SWR is usually called in on El Dorado County cases where injured, orphaned or sick wildlife are concerned. Their mission is to rehabilitate wildlife with minimal human/wildlife interaction in hopes to better the chances of a successful release back into the wild.

“We anesthetized her and debrided and cleaned the wounds,” said Dr. Marsha Birdsall, volunteer veterinarian with SWR. “Once she was bandaged up, we transferred her to one of our home rehab facilities. These are homes of our volunteer rehabbers that have larger properties with larger outdoor enclosures.”

At the home rehab facility, the fox was able to heal in an outdoor environment and be monitored by wildlife cameras set up around the property. This helps ensure that the animal will not imprint on people or begin to rely on human interaction while being monitored.

After nearly eight weeks, the fox’s injuries were getting better, but with some setbacks. Her burned and damaged skin and paws were healing, but she lost every paw pad, claw and several toes. SWR was concerned the lack of claws, paw pads and toes would make it difficult to return the kit to the wild.

“Our action plan in general is to return these animals to the wild,” said Buckles. “But we were concerned she wouldn’t be able to catch live prey or protect herself from larger animals.”

Thinking the fox would not be able to hunt or climb trees to avoid predators without her claws and toes, SWR reached out to their grant partner CDFW to see if the department knew of another facility that would take the kit in as an educational animal.

CDFW contacted Sonoma County Wildlife Rescue in Petaluma, and on Dec. 14, 2021, the kit was transferred to their facility where the team planned for it to live out its days at their outdoor facility. What the Sonoma County rehab team saw the kit doing while monitoring their property’s wildlife cameras, no one saw coming.

“The fox started showing signs that she could catch prey,” said Buckles. “She also found a way to climb. She would wrap her limbs around the tree, like a hug, and shimmy her way up.”

Sonoma County Wildlife Rescue began continuously conducting live prey testing with the fox, and it continuously would hunt and eat the prey. By mid-February, despite not having front or back claws, the fox was digging, climbing, hunting and grooming itself effectively.

“Now knowing the fox can hunt, climb, defend and groom itself we made the decision to bring her back from Sonoma County Wildlife Rescue and release her back into the wild in El Dorado County,” Buckles said.

The fox was released back into the wild in El Dorado County on March 2, 2022, after nearly six months of being rehabbed.

“We don’t usually name the animals in our care because they are not our pets, they’re wild animals,” said Buckles. “… but this fox overcame so much, and we were all so invested in her making it back to the wild that we now call her Phoenix, because there’s a story that says the Phoenix bird rises out of the ashes. That’s what this fox did, it rouse out of the Caldor Fire ashes.”

CDFW’s Wildlife Rehabilitation Program currently works with more than 80 permitted rehab facilities (PDF) like SWR and Sonoma County Wildlife Rescue across the state. For the 2022 grant cycle alone, CDFW has distributed $547,000 to these facilities for them to continue their work in their communities.

“These facilities along with their satellites and army of volunteers are the ones who put in the long, hard hours year after year to successfully rehab injured, orphaned or sick animals and birds of California,” said Heather Perry, CDFW’s Wildlife Rehabilitation Program Coordinator. “When tax-filers make the choice to contribute to the Native Wildlife Rehabilitation Tax Fund, their support allows for grant funding that SWR, Sonoma County Wildlife Rescue and many of our other permitted rehab facilities utilize to fund their work. The story of the Caldor Fire fox is just one example of what we can do when we all work together.”  

For more information on the Native Wildlife Rehabilitation Fund, please visit

*According to CalFire records, the Caldor Fire started on Aug. 14, 2021and was active for 67 days. The fire burned through nearly 222,000 acres in El Dorado, Amador and Alpine Counties and destroyed 1,003 structures.

Media contact:
Leticia Palamidessi, CDFW Education and Outreach, (916) 708-8517

Categories: Science Spotlight
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