Science Spotlight

CDFW Scientific Aide Aimee Taylor prepares electrofisher to harmlessly catch Paiute cutthroat trout in North Fork Cottonwood Creek.


The extremely rare Paiute cutthroat trout (PCT). Photo by William Somer for CDFW.


Aimee Taylor and Senior Environmental Scientist Jeff Weaver electrofish PCT in North Fork Cottonwood Creek.


Jeff Weaver, USFWS Biologist Chad Mellison and others take genetic samples from the fish.


The project’s lead biologist, Bill Somer, and Chad Mellison transfer the trout from CDFW’s tank truck to cans for the ride to Silver King Creek, by pack mule.


The CDFW-FWS-USFS team packs pure PCT in milk cans through the Silver King drainage.


Bill Somer releases Paiute cutthroat trout into Silver King Creek, above Llewellyn Falls.


Team members measured each Paiute cutthroat trout caught at White Mountain.

The California Department of Fish and Wildlife (CDFW), U.S. Fish and Wildlife Service (FWS), and U.S. Forest Service (USFS) have returned a rare trout species to its home water after a 71-year absence.

In 1946, poachers were decimating the Paiute Cutthroat Trout (PCT), a species whose native range was limited to a nine-mile section of Silver King Creek (Alpine County). To ensure the species’ survival, the USFS and Eastern Packers Association translocated 401 of these fish to North Fork Cottonwood Creek in Inyo County’s White Mountains. This population has persisted in isolation from other forms of trout and has recently provided important restoration options for resource managers. None of this would have been possible without the foresight of concerned biologists seven decades ago.

The conservation history of this rare trout is complex. The initial “conservation” measure was entirely inadvertent. In the early 1900s, Basque sheepherders in the area caught and transported PCT into the previously fishless portion of Silver King Creek above Llewellyn Falls. This early within-basin transfer was the salvation of the PCT, since non-native species were later introduced below the falls. The falls prevented non-natives from reaching the habitat above and protected PCT from hybridization and competition.

The FWS listed PCT as endangered under the Endangered Species Preservation Act of 1966 – the precursor to the federal Endangered Species Act (1973). The species was down-listed to threatened status in 1975, in order to facilitate management and restoration and to allow regulated angling. In 1994, CDFW, FWS and USFS began developing a restoration plan to remove non-native fishes from Silver King Creek and return the PCT to its native waters. From 2013 to 2015, the partner agencies treated 11 stream miles of Silver King Creek and three tributaries below Llewellyn Falls with a fish toxicant, rotenone, to remove all non-native fish species.

The PCT population in Upper Fish Valley, an area of Silver King Creek above the falls, has been considered a primary source for restocking the recovery area. Unfortunately, that population was heavily impacted by the extreme 2012-2016 drought. During this extended drought, lack of snow cover resulted in the stream freezing almost solid during cold snaps. In order to offset the resulting population decline, the partner agencies caught 86 pure PCT in North Fork Cottonwood Creek. On August 23, 2017, the fish were planted back into Silver King Creek above Llewellyn Falls.

Agency staff met in the White Mountain Wilderness (Inyo National Forest) and, along with volunteers and pack mules, hiked from their campsite to North Fork Cottonwood Creek. There, the team used electrofishers to retrieve descendants of the fish moved back in 1946. The fish were hauled out by mule, put in a specialized transport truck, and driven approximately 100 miles to the Carson Iceberg Wilderness. Another mule team then hauled them back to Silver King Creek. Thanks to careful handling by the collection and transport teams, every fish survived the trip home.

Due to its limited habitat, the Paiute Cutthroat Trout has been called the rarest, but most recoverable, form of trout in the United States. With the most recent success of this partnership, and due in large part to the foresight of conservationists in the past, the future looks bright for this beautiful native salmonid.

Learn more on the Paiute cutthroat trout web page.

Photos by Joe Barker, courtesy of U.S. Fish and Wildlife Service, except as noted.

Top photo:
Liz Vandentoorn, from the Inyo National Forest Region 5 Center of Excellence, leads a pack mule team and state and federal scientists to North Fork Cottonwood Creek to capture Paiute cutthroat trout and return them to Silver King Creek.

Native to the California coast and the California/Nevada state line, the Myrtle’s silverspot butterfly feeds on the nectar of the monardella flowers.


One of 33 species of birds listed as threatened or endangered by the State of California or the federal government, the western snowy plover is in jeopardy of disappearing from the dunes.


in 2017, two years after treatment, the southwest side of the herbicide treatment area shows little regrowth of invasive plants.

Sandy dunes along the California coast often feature hardy European beachgrass and a succulent, freeway iceplant, that many assume is part of the native flora. However, these groundcover plants were originally introduced in the 1800s by Gold Rush settlers who were hoping to keep sand from moving to the nearby roads, railroads and land. Today, they are invasive species that out-compete the native plants and the animals that live there.

Over the years, the invasives took over the native Tidestrom lupine and beach layia, causing them to be placed on the federally endangered species list. The endangered Myrtle’s silverspot butterfly and the threatened snowy plover are dependent on native plants like these, and today, they too are in jeopardy of disappearing from the area.

“Snowy plovers naturally select open areas to nest so that they can more easily spot predators,” said CDFW Environmental Scientist Laird Henkel. “The European beachgrass spreads quickly making the dunes less desirable as a place for these birds to nest.”

Scientists determined that removing these invasive plants would be the best way to restore the dunes and the ecosystem that depends on them. To this end, CDFW awarded $54,000 in Environmental Enhancement funds to a project on the Point Reyes North Great Beach, located in Marin County, to restore the native sand dune plants on a 13-acre area in 2015. The fund committee selected the Point Reyes application because of the success of their previous dune restoration projects.

Point Reyes National Seashore staff oversaw the removal of the invasive plants on the dunes. Their contractors spray-treated the dunes with an herbicide and uprooted the invasives by hand; they worked during times of low winds and no rain, to protect other natural plants, wildlife, nearby farms and the public from overspray.

Point Reyes scientists monitored the treated area with an easy-to-use mapping tool called photo point monitoring – an effective method of monitoring vegetation and ecosystem change. Visual surveys and the mapping program showed just a one-to-three percent regrowth of the invasive plants over time, while previous restoration projects showed much more regrowth.

“The project area represents a vital link between earlier restoration efforts near Abbotts Lagoon and new restoration efforts at the AT&T cell tower area, enabling the park to move closer towards its goal of several miles of dune habitat not wiped out by invasive plants such as European beachgrass and iceplant,” said Point Reyes National Seashore Ecologist Lorraine Parsons.

CDFW-OSPR and the Point Reyes staff consider the project’s first objective – eradicating invasive European beachgrass and ice plant – a success. Earlier this year, scientists noticed in treated areas the reappearance of wild cucumber. The reappearance of other native plants such as the mock heather, California blackberry and yarrow, and wildlife is the second objective, the success of which will be determined over time. Other treated areas in the region show beachgrass breakdown and increased native dune scrub and mat species after six years.

Photos courtesy of Point Reyes National Seashore and the U.S. Fish and Wildlife Service.

Top photo: The Point Reyes National Seashore staff oversee contractors spray-treating the dunes with an herbicide.

Working late, Mojave River hatchery staff apply FDA-certified epoxy coating to hatchery rearing ponds.


CDFW fish transportation truck at Fillmore Hatchery


Acting Mojave River Hatchery Manager Forest Williams at work


A hatchery crew releases trout into the Feather River


A fishy view of trout planting on the Feather River

The beginning of trout fishing season in Southern California is just around the corner, and CDFW biologists and hatchery staff are striving to maximize hatchery trout availability for the many anglers who will cast lines in coming weeks. Trout angling in lower-elevation waters of Southern California generally begins in November and continues through April, to correspond with colder water temperatures that can sustain stocked trout.

Precise temperatures are just one of the criteria that must be met before trout stocking begins. Currently, these conditions are approaching optimal levels, but CDFW is running about two weeks behind schedule due to unforeseen circumstances at Mojave River and Fillmore trout hatcheries, two of CDFW’s southernmost facilities.

The Mojave River Hatchery, built in 1947, raises and stocks a ten-year average of 340,000 pounds of catchable trout per year. Beginning in June of this year, extensive maintenance and facility upgrades necessitated turning off the water for a six-month period. While the completed upgrades will ultimately result in better and more efficient trout production for Southern California, the project ran about two months behind schedule. Water is scheduled to flow again at Mojave River Hatchery in late November and the hatchery will be populated with fingerling trout for fast growth. Mojave’s year-round water temperatures yield fast trout growth resulting in maximized yield in minimal time.

While the Mojave River Hatchery was closed, Fillmore Hatchery, built in 1941 on the Santa Clara River, experienced a significant loss of trout inventory intended for Southern California angling due to gas bubble disease. Gas bubble disease is a result of supersaturated gasses (oxygen, nitrogen and carbon dioxide) present in well water pumped from a deep aquifer. While Fillmore Hatchery is equipped to aerate this water and make it suitable for trout, an unknown variable (possibly a drought-depleted and then recharged aquifer) overwhelmed that ability. In an average year, Fillmore Hatchery produces about 400,000 trout for lakes and streams in Southern California. To reduce fish losses from gas bubble disease in the last several weeks, catchable fish were stocked from Fillmore to appropriate waters, and some fish were transferred to other hatcheries. Ultimately, the gas bubble disease at Fillmore resulted in a loss of about 50 percent of inventory. While emergency measures taken by Fillmore staff and

CDFW fish pathologists resulted in better conditions and lower gas super-saturation, the hatchery must be depopulated so that the issue can be addressed entirely. As soon as all trout are removed, hatchery staff and scientists will increase the gas diffusion capability of aeration towers at Fillmore, in order to handle supersaturated well water for the short and long term.

The status of these two hatcheries presented a substantial problem for trout stocking in Southern California that was solved in part by hatcheries in Central and Northern California. These hatcheries have sufficient catchable size trout to supply Southern California’s approved waters immediately and in coming weeks. Thanks to strategic planning and trout production at a statewide level, Northern and Central California can supply fish to Southern California without impacting originally scheduled trout releases in their respective areas.

Trout stocking for Southern California waters will begin this week and hatchery trucks are on the move. Hatchery staff will work quickly to distribute trout to as many approved waters as possible. Trout stocking to Southern California will initially be lighter than usual, but will likely pick back up in 2018. As Mojave River Hatchery comes back online, fish transferred to that facility will be fed and reared to maximize daily growth. We anticipate another large batch of catchable trout available for Southern California toward early spring 2018.

Hatchery staff will be doing everything possible, statewide, to maximize trout production and releases to approved waters in the coming months. Staff work diligently for the angling public and appreciate their continued support.

The statewide planting schedule is updated in real time online.

CDFW photos. Top: Steelhead trout at Mokelumne River Hatchery

Lassics lupine grows under protective cages.


Richard Macedo, Habitat Conservation Planning Branch Chief constructs a cage to protect rare, endangered Lassics lupine.


Lassics lupine grows under protective cages.

Biologists from three government natural resource agencies banded together this summer in an unusual effort to help preserve a species under threat of extinction. They lugged materials to build wire cages into the rough terrain of the remote Lassics mountains near the border of Humboldt and Trinity counties in an effort to protect their target. However, these cages were not built to trap animals; they were constructed to keep animals out.

The barren, green serpentine slopes of Mount Lassic, located in a seldom-visited part of Six Rivers National Forest, are home to one of California’s rarest plants: the Lassics lupine (Lupinus constancei). Lassics lupine is a short plant in the pea family that has bright rose-pink flowers. Only approximately 450 adult Lassics lupine plants were observed during 2017 monitoring of the species conducted by the U.S. Forest Service and the U.S. Fish and Wildlife Service, with assistance from CDFW.

Rodents such as deer mice, squirrels and chipmunks have been eating so many Lassics lupine seeds from the plants that, absent intervention, the species appears to be on the path to extinction within the next 50 years (Kurkjian et al. 2016).

Biologists believe that historical suppression of fires in Six Rivers National Forest beginning in the early 1900s may be indirectly responsible for the encroachment of forest and chaparral into Lassics lupine habitat. Fires that were put out quickly did not grow large enough to reduce encroaching forest, and therefore the forest expanded. With the encroaching vegetation came more seed-eating rodents that depend on vegetation cover for protection from predators.

In 2003, the U.S. Forest Service, U.S. Fish and Wildlife Service and other researchers began an emergency attempt to halt Lassics lupine’s trend towards extinction. Each summer, biologists set off on the laborious hike up Mount Lassic to place cylindrical wire cages over as many flowering Lassics lupine plants as possible. Each cage is anchored to the ground to prevent rodents from squeezing underneath.

The cages are remarkably effective at stopping rodents when properly installed, and they remain on the plants for the duration of the growing season. After Lassics lupine fruits have matured, they often split open suddenly and send seeds flying through the air up to 13 feet away. The cages are then removed each year before the onset of winter snow.

“Protecting endangered species is California’s policy and plants like the Lassics lupine could disappear within our lifetimes,” explained Jeb Bjerke, a biologist with CDFW’s Native Plant Program. “We should do what we can to save these unique plants for the future.”

In 2015, in the midst of an historic drought, an 18,200-acre fire spread through the Lassics, killing many Lassics lupine plants and charring the chaparral vegetation nearby. The fire had little effect on the forest that encroaches into Lassics lupine habitat, but preliminary studies suggest that the fire may have reduced rodent density in the burned chaparral. Despite the apparent reduction in rodent density following the fire, the impact from rodents eating Lassics lupine seeds remains high. Continued caging of Lassics lupine plants therefore remains critical for preventing extinction of the species until a more permanent solution can be implemented, such as significant reduction of encroaching forest. However, such efforts are expensive to plan and implement. As the primary land manager, the U.S. Forest Service would likely be the lead agency in future protective actions.

In 2016, the California Fish and Game Commission received a petition to list Lassics lupine as an endangered species under the California Endangered Species Act and the species was designated a candidate species earlier this year. CDFW is in the process of producing a status review for Lassics lupine that will include a recommendation to the California Fish and Game Commission on whether listing the species is warranted. The legislature directs all state agencies, including CDFW, to seek the conservation of endangered and threatened species.

“I hope that CDFW can continue to partner with the U.S. Forest Service and U.S. Fish and Wildlife Service to protect the Lassics lupine from extinction,” Bjerke said.

For additional information on this subject, please see:

• Report to the Fish and Game Commission, Evaluation of the Petition from Mr. David Imper and Ms. Cynthia Elkins to List the Lassics Lupine (Lupinus constancei) as an Endangered Species under the California Endangered Species Act (PDF).
• Kurkjian, H.M., S.K. Carothers, and E.S. Jules. 2016. Seed predation has the potential to drive a rare plant to extinction. Journal of Applied Ecology 54:862–871.

California Department of Fish and Wildlife photos by Jeb Bjerke

California leaf-nosed bats. CDFW photo by retired biologist Andy Moore.


Hundreds of bats in flight. ©Dave Feliz, all rights reserved.


Little brown bat with white-nose syndrome. US Fish and Wildlife Service photo.


Townsend's big-eared bat in flight. National Park Service photo.

The last seven days of October are celebrated each year as Bat Week – a time to learn about the importance of bats in our environment.

Bats are nature’s best pesticide. According to a study by the University of California, Davis, Division of Agriculture and Natural Resources, each of these small mammals eats between half and 100 percent of its own weight in insects every night. Some California species consume as many as 600 insects per hour. Imagine living with all the mosquitoes, flies, midges, moths and agricultural pests that are now consumed by bats!

In monetary terms, the natural pest control that bats provide is extremely valuable to the state’s $54 billion per year agriculture and $450 million timber industries. The bats’ appetite reduces the need for chemical pesticides, reduces crop losses and curtails the spread of crop diseases. According to the US Geological Survey, a recent economic analysis indicated that insect suppression services provided by bats to American agriculture is worth something between $4 billion and $50 billion per year.

California Department of Fish and Wildlife (CDFW) Senior Environmental Scientist Scott Osborn notes the estimate’s wide range makes it hard to know exactly how much money bats save farmers. “But even the low estimate, $4 billion, is an impressive amount,” he said. “Bats are an important part of integrated pest management systems.”

As the wildlife trustee agency in California, CDFW is engaged in several activities to help us understand the conservation status of bats in the state, as well as to address threats to bat populations. At statewide, regional and local scales, our scientists have been deploying acoustic bat detectors to determine the distribution of California’s 25 bat species. When CDFW’s bat acoustic data are combined with data collected by partners at other state and federal agencies, academic researchers and non-governmental organizations, we should have more accurate knowledge of where various bat species occur, as well as their seasonal movements.

White Nose Syndrome (WNS) is now a real threat to California’s bats. WNS is a fungal disease that is estimated to have killed more than 6 million bats in eastern North America. With the discovery of WNS for the first time on the west coast (in Washington state) last year, California is bracing for potentially devastating impacts to our bat populations. CDFW is working with the US Fish and Wildlife Service and other partners to conduct surveillance for the fungus that causes the disease, as well as develop plans to manage the disease when it arrives in California. So far, all of the samples collected from bats and their roosts in California have been free of the fungus, but increased vigilance is necessary to help ensure the disease is detected immediately when it arrives. Special measures to reduce the impact of WNS on hibernating bats may include closing caves and other roosts to visitors, because people can unwittingly spread the fungus on their clothing, shoes and gear. Ultimately, it is hoped that ongoing research into the disease will provide tools to either eliminate or control the fungus, both in the environment and in infected bats.

To learn more about the exciting world of bats and how you can “Go to Bat for Bats!” check out the Bat Week 2017 website.

Top photo: A California bat in a crevice. ©Dave Feliz, all rights reserved.