Science Spotlight

Fate has not been kind to the San Joaquin kit fox (Vulpes macrotis mutica).

Shrinking habitat caused by urbanization and agricultural expansion landed this Central Valley native on the federal Endangered Species List decades ago. California’s total population of San Joaquin kit foxes may now be down to a few thousand animals. To make matters worse, its favorite food, the kangaroo rat, is likewise endangered as the desert habitat it prefers continues to disappear.

Wildlife biologists took heart, however, in a population that seemed to be thriving within the city limits of Bakersfield. Unlike San Joaquin kit fox populations in other parts of the Central Valley range, the Bakersfield foxes adapted quite nicely to urban life. Their number – estimated between 200 and 400 animals – has evidently seemed to be holding steady and possibly increasing.

Their cute and cuddly appearance make them popular with city residents. Earlier research showed the population was healthy and genetically robust. Wildlife biologists were counting on those urban foxes to ensure the species’ survival should kit fox populations completely collapse elsewhere.

Today, those Bakersfield kit foxes are under siege, suffering from an outbreak of highly infectious sarcoptic mange. Mange – a skin condition caused by parasitic mites -- leads to hair loss, open wounds from scratching and, ultimately, death. The first case was detected among the kit fox population in March 2013, and since then, more than 200 cases have been documented. The epidemic has grown worse every year.

Given the importance of the Bakersfield population, CDFW, the U.S. Fish and Wildlife Service, the California State University, Stanislaus, the University of California, Davis (UCD), and various nonprofit wildlife groups have all joined forces to combat the mange.

Jaime Rudd, an environmental scientist in CDFW’s Wildlife Investigations Lab in Sacramento, is leading CDFW’s efforts while simultaneously writing her UCD Ph.D. dissertation on the outbreak. Rudd is researching ways to prevent mange from spreading to healthy animals, and assisting Stanislaus State’s Endangered Species Recovery Program with trapping and treating diseased foxes.

Severely diseased kit foxes are trapped and transported to the California Living Museum, a Bakersfield wildlife rehabilitation facility and zoo. There, the kit foxes are hospitalized, given life-saving antibiotics and fluids and treated with a topical pet product that kills the mites. The foxes often need months of treatment before they are healthy enough to release. And although the intervention saves individual lives, the process is costly and time-consuming – and doesn’t prevent the treated fox from getting mange a second or third time.

Rudd is making good use of her undergraduate degree in molecular biology, analyzing the DNA of the mites to see if they might be related to those in dogs and coyotes, which could be spreading the mange to the foxes.

“Essentially, we want to look at their molecular signature to see if these mites are related,” Rudd said.

Rudd is studying a group of wild kit foxes living on the CSU Bakersfield campus, which no doubt are supplementing their diet with burger bits and pizza crusts discarded by college students. Rudd is monitoring the group with trail cameras, outfitting some foxes with radio tracking collars and others with the type of preventative flea and tick collar you might use on a pet dog or cat.

“We want to evaluate the efficacy of these collars,” she said. “If they’re only going to work for two months, the collars won’t help us slow down the spread of mange, so is it really worth the effort of putting them on? But if they’re going to work for five months or more, then it might be worth the effort.”

If there is any hope sustaining Rudd and her colleagues in this important, though often disheartening, work, it’s this: “The fact we are not seeing mange in the outlying populations is cause for optimism,” she said. “If nothing else, we can at least try to keep it from leaving the city.”

The Pacific herring – much like squid and anchovy – is an important forage fish that supports a commercial fishery and provides a prey source for all manner of fish and wildlife, including whales, seals, sea lions, sturgeon, salmon, pelicans and numerous other species of birds and invertebrates.

The largest population of Pacific herring in California spawn in San Francisco Bay, and since 1972, CDFW has been responsible for monitoring and managing their numbers. CDFW uses annual vegetation dive surveys and spawn (herring eggs) surveys to calculate a population estimate each year. CDFW also uses commercial fishery and mid-water trawl survey information to look at the composition and general condition of the spawning population.

CDFW has just completed and posted online the 2016-17 San Francisco Bay Season Summary for the Pacific herring fishery. The good news is that the spawning population, estimated at 18,300 tons, is up slightly from the 2014-15 and 2015-16 seasons. But it is still far below the historical average of 49,400 tons. Less than ideal ocean conditions are cited for the below-average numbers.

CDFW closely regulates the commercial Pacific herring fishery in the San Francisco Bay, setting quotas, season dates and using the commercial catch data to help further analyze the size, age and condition of the spawning population. Typically about six inches long, the fish primarily are harvested for their roe, which is prized in Japan. CDFW maintains a blog on the species called the Pacific Herring Management News.

This summer marked the end of an incredible journey for four dozen of California’s designated state freshwater fish, the golden trout, as they returned home after 10 months away. The fish traveled more than 500 miles in tanks and buckets, by hand and by mule, en route to their native waters 9,000 feet up in the Sierra Nevada range.

The journey began last fall after CDFW scientists observed that ongoing drought conditions were severely impacting the rare trout’s mountainous habitat. A decision was made to rescue 52 fish – a representative population that could repopulate the stream and save the species if drought conditions worsened.

Golden trout are one of California’s most iconic trout species. They are native to only two stream systems in the southeast Sierra Nevada – Golden Trout Creek, and the South Fork Kern River in Tulare County. Volcanic Creek, which is home to the rescued fish, connects with Golden Trout Creek during runoff and high-water level years.

The journey began in September 2016, when fisheries biologists made the two-day trek into the mountains to gather the trout. The captured fish were transported to the American River Trout Hatchery near Sacramento, where technicians monitored them, often around the clock. After nine months at the hatchery, the fish were ready to start the long trek back to their home waters. Crew members transferred the fish from the hatchery to a fish tanker truck and hauled them more than seven hours overnight to the trailhead at an elevation of 10,000 feet in the southern Sierra.

The crew met up with a CDFW team that would escort the fish on horseback, 16 miles into the Inyo National Forest. Federal laws forbids motorized vehicles on wilderness land, which left the team no option but to transport the fish by mule train in fish cans.

The operation took tremendous teamwork from multiple divisions in CDFW and the National Forest Service. Ultimately, the CDFW team successfully returned 48 fish to their natural element. Four died in captivity over the winter. CDFW officials consider that a normal mortality rate. Scientists remain optimistic that these iconic fish will continue to thrive and perhaps even be on-track for a brighter future.

See related VIDEO.

California’s coastal waters are home to seven species of abalone, and all but one are endangered or listed as species of special concern. The white abalone in particular has been nearly decimated by overfishing and disease, and scientists can find no evidence that the remaining population is reproducing in the wild. In order to avoid loss of the entire species, CDFW and partner agencies have formed the White Abalone Recovery Consortium, which will employ captive rearing and restoration stocking efforts and extensive public outreach in order to save these animals from extinction. It will be an ongoing, long-term project, but all signs point to future success – already there are more white abalone thriving in the captive breeding program than the entire population living in the wild.

Read more about the efforts to restore California’s white abalone – and learn what you can do to help! – on the CDFW Marine Management News Blog.

The latest issue of California Fish and Game, CDFW’s scientific journal, is now available online. This century-old quarterly journal contains peer-reviewed scientific literature that explores and advances the conservation and understanding of California’s flora and fauna.

The endangered salt marsh harvest mouse (Reithrodontomys raviventris) graces the cover of California Fish and Game, Volume 103, Issue I. Researchers ventured into the pickleweed to study the tiny mouse, which is endemic to the marshes surrounding the San Francisco Estuary Bay and its tributaries. The mice were fitted with tiny radiotelemetry collars and tracked for three years. Researchers documented some curious behavior in the resulting paper, “Potential evidence of communal nesting, mate guarding, or biparental care.” The accompanying photos provide a fascinating glimpse into an active nest.

Another paper, “Documentation of mountain lion occurrence and reproduction in the Sacramento Valley of California,” explores the potential for mountain lions to exist in fragmented habitats if there is adequate connectivity with larger blocks of suitable habitat and sufficient prey. The study used camera traps to document populations of mountain lions in the Sacramento Valley’s Butte Sink, which is made up of relic riparian habitats interspersed with managed wetlands. The photos show healthy mountain lions moving through habitat that has long been considered unsuitable due to extensive agricultural and urban development.

The article, “Mussels of the Upper Klamath River, Oregon and California,” reports on sampling efforts that expand existing baseline population data on freshwater mussels in the Upper Klamath River. The sampling efforts may ultimately assist with protection, mitigation and enhancement efforts for large bi-valve species.

The final paper provides insights into the benefits deer and elk derive from licking mineral rocks. Researchers took samples of “lick sites” that were used by California black-tail deer (Odocoileus hemionus columbianus) and Roosevelt elk (Cervus canadensis roosevelti) in the Klamath Mountains, Siskiyou County. After performing a detailed analysis of the elemental content of each lick site, the researchers concluded that each lick site offers a different smorgasbord of minerals, and in varying concentrations. The study’s objective is to begin identifying, classifying, and analyzing important mineral lick sites to benefit future ungulate management efforts.

As it has for the past 103 years, California Fish and Game continues to publish high-quality, peer-reviewed science that contributes to the understanding and conservation of California’s wildlife. We look forward to witnessing the contributions of the next installment.

Download the entire Winter Issue 103 (PDF) in high resolution, or browse individual articles in low resolution.