Science Spotlight

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

Market Squid Reproducing. Photo credit: Mark Conlin Photography


Highest value marine fisheries, 2015-2019 - click to enlarge


Squid fishing fleet near Monterey. CDFW photo by Carrie Wilson - click to enlarge


Squid fishing fleet at night. CDFW photo by Carrie Wilson - click to enlarge

Arriving on the heels of the farm to fork movement, the COVID-19 pandemic has disrupted supply chains and altered product demand, which has inspired businesses to restructure and Californians to pay particular attention to where their food comes from. Many understand that almonds, artichokes or lettuce are grown in their own backyard, mostly in the Central or Salinas Valleys. But when residents are asked about wild-caught food sources coming from the ocean, tuna, salmon or perhaps rockfish might immediately come to mind. While those are indeed popular fisheries, the largest of California’s commercial fisheries actually target invertebrates, not fish!

Invertebrates are animals without a backbone, such as the tidepool favorites, sea stars and anemones. But there are many more invertebrates around the world, both swimming and sedentary, that are highly sought after for food – and their popularity is on the rise. California’s largest marine commercial fisheries in terms of volume and value are market squid and Dungeness crab, with well over 100 million pounds landed and more than $30 million in revenue in a typical year for the squid fishery.

Market squid, the invertebrate known to diners as the popular dish calamari, use ocean currents, jet propulsion and prehistoric instincts to travel up and down the continental shelf of California. These slippery siblings of octopuses live very short lives (less than nine months) and produce heaps of eggs, somewhere on the order of 2,000 to 7,000 per female!

When conditions are right, squid show up in droves to reproduce in coastal waters. After reproducing for just a few short days, they die as a natural part of their life cycle. This means the entire population replaces itself in less than a year. These qualities lend to a high volume of squid available for fishermen, cost-effective management and a sustainable fishery. Squid are also used as bait to catch a wide variety of fish species and can be found at many coastal tackle shops or on live bait barges, mostly in Southern California.

If you see very bright lights from groups of boats on the water at night, it is likely the squid fishing fleet in action. Fishermen have used this technique for more than a century because squid are attracted to the lights, which mimic the moonlight. As described in an historic Fish Bulletin from 1965, the market squid fishery began in Monterey around 1863. The early fishing methods involved rowing a skiff with a lit torch at the bow to aggregate the squid. Then, two other skiffs would maneuver a large net around the school.

In today’s fishery, squid are typically caught using a purse seine, a large circular net which is “pursed” at the bottom to contain the school. Once the school of squid is brought closer to the vessel, a long tube is then used to suck the squid out of the net and onto the boat.

Only a limited number of vessels may fish for squid in California, and during the weekends (from Friday afternoon to Sunday afternoon) squid fishing is closed to allow for uninterrupted reproduction. In many fisheries, highly sophisticated mathematical models are used to estimate the available population for an upcoming season and ultimately to decide how many fish can be sustainably caught. Because market squid are short-lived, highly responsive to ever-changing environmental conditions and do not behave like most fish, traditional models are ineffective.

For this reason, the fishery is monitored using the egg escapement method, which is essentially an estimate of how many eggs are released prior to female squid being caught. By comparing the average number of eggs that a female squid will produce to squid samples collected at the docks, biologists can calculate how many eggs were produced each year. This is used to look for trends or major shifts in how the squid fishing fleet is interacting with the stock. Biologists continue to explore ways to pair egg escapement information with population estimates, environmental variables, fishing behavior and economics.

Fishing for market squid is a long-standing tradition in California and normally provides for a large export market. But a number of recent factors, including the COVID-19 pandemic, have inspired stronger local markets for many fisheries, such as squid. This means more restaurants, businesses and consumers are buying directly from the docks, shortening the distribution chain. Boat captains, crew, processors, distributors and diners eagerly await the arrival of squid, especially around spring and summer on the central California coast when fishing is generally the most successful. If history repeats itself, vessels will move to Southern California in the fall and winter, where the Channel Islands tend to be the hot spot for squid fishing. But in response to a changing climate, the range for this species is likely to expand northward, forcing the fishing industry and the biologists studying squid to adapt as well!

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

The burned paw pad of a bear found in the wake of the Bear (North Complex).


Wildlife veterinarians document the bear’s injuries prior to treatment.


Burn treatment protocol includes the use of sterilized fish skins as a natural bandage for damaged tissue.


Wildlife veterinarians assess a mountain lion that was burned in the Bobcat Fire.


The burned paw pad of a mountain lion found in the wake of the Bobcat Fire.

In early December 2017, wildlife veterinarians from the UC Davis School of Veterinary Medicine and CDFW teamed up to try to save the life of a black bear that sustained third-degree burns in Southern California’s Thomas Fire. The innovative treatment involved the use of tilapia skins as natural bandages for the bear’s paw pads while she recovered from her injuries at CDFW’s Wildlife Investigations Laboratory (WIL) in Rancho Cordova.

Before the month was out, two more victims of the Thomas Fire joined her – a second burned bear, and a young mountain lion. The fish skin treatments were successful and all three patients survived – the bears were released back to the wild, and the orphaned lion cub, which was deemed too young to survive on its own, was placed in a sanctuary. In August 2018, the Carr Fire near Redding sent a fourth burned ursine patient to the lab, which was again treated and successfully released.

The veterinary science was groundbreaking, and the opportunity so very exciting for the team involved, especially the project’s leads, UC Davis’s Dr. Jamie Peyton and CDFW’s Dr. Deana Clifford.

Unfortunately, these four cases were just the beginning, with additional wild animals being burned in the Carr and Camp fires. The 2020 fire season in California has been even more severe, with more than 7,700 individual fires consuming 3.7 million acres of wildlife habitat so far. On Sept. 11, the WIL received its first burn patient of 2020, a 370-lb. male black bear from the aptly named Bear Fire (which later became the North Complex Fire) in Butte County. On Sept. 21, the second patient, a female mountain lion from the Bobcat Fire in Los Angeles County, arrived. On Sept. 30, a 520-lb. male bear was brought in from the Zogg Fire in Shasta County.

“Both bears and the lion are receiving our burn protocol, including the fish skin bandages, and we are optimistic that their burns will heal so that they can be released,” Dr. Clifford said. “But it’s likely that we will receive more wildlife with burns … we are only halfway through the regular fire season.”

As California’s wildfires grow in intensity, size and frequency, our state’s wildlife veterinarians are being forced to reexamine the big picture -- how wildlife are faring, to what extent we should intervene and what our capacity is to do so.

“While we know what a devastating effect wildfires have on our human population – and, to a lesser degree, domestic animals – our knowledge about how wildfires affect wildlife (non-domestic animals) during and immediately after the disaster has been so limited,” Dr. Peyton said. “There’s always been this prevailing mindset that ‘they’ll get out of the way,’ or that they can manage if left alone, but that needs to change. With the increase in frequency and severity of disasters, wildlife cannot escape. Without human interference, these animals will suffer and succumb, due not only to their injuries but also to the loss of food, water and habitat. It is our obligation to provide the missing link for the wildlife that share our home.”

A successful response to this developing need will require resources – time, money, and professional expertise. In an effort to build these resources quickly and efficiently, CDFW and the UC Davis School of Veterinary Medicine have drawn up a proposal for a wildlife search and rescue, field triage, transport and long term rehabilitation care system for injured wildlife resulting from wildfires.

The Wildlife Disaster Network, as it’s been dubbed, is modeled after the Oiled Wildlife Care Network (OWCN) – a similar structure created in 1994 to mobilize volunteers and professionals to help save shorebirds and other wildlife that are injured during coastal and inland oil spills.

The new Wildlife Disaster Network will include veterinarians, wildlife biologists, ecologists, trained animal care volunteers and rehabilitation centers that follow the four core principles already set by the OWCN: readiness, response, research and reaching out. There will also be field reconnaissance in the aftermath of fires, conducted by UC Davis-affiliated staff, with the approval and oversight of Incident Command, when conditions are deemed safe to do so. In addition, they have established a hotline for first responders, utility workers, and the general public to call in for assistance with coordinating care for injured wildlife: 1 (800) 942-6459 (1-800 WHC-OIL-9).

“The idea is to create a collaborative process – which works within any existing emergency incident command structure – that brings experts together to respond to injured animals and prevent suffering,” Dr. Clifford said.

In addition to easing the suffering of animals that are trapped by wildfires in California’s changing climate, the vets hope that the Wildlife Disaster Network will allow for California’s wildlife veterinarians and disaster response professionals to add to their knowledge, and promote further collaboration with others to share this knowledge. The long-term impacts on wildlife from these massive disasters are also largely unknown and in critical need of further investigation and intervention, especially in areas with threatened species. All of the data collected by the participants of the Wildlife Disaster Network – such as necropsy reports on the animals who do not survive their injuries – will help build a framework of scientific knowledge that didn’t previously exist.

Initially, equipment used in this effort will be loaned on an as-needed basis by the OWCN and CDFW. Ongoing financial support for this effort will be through fundraising from private donors via a gift fund to be established by UC Davis.

“These animals in need of care are a visible, tangible and poignant reminder that climate-changed induced wildfires are impacting our wildlife and ecosystems,” said Dr. Clifford. “They remind us that each of us should continue efforts to reduce the impacts of climate change.”

Donations to the Wildlife Disaster Network can be given online at the California Wildlife Conservation General Support website or by calling the UC Davis School of Veterinary Medicine, Office of Advancement, at (530) 752-7024.

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

CDFW photos