Science Spotlight

Forensic Specialists Kelly Carrothers (l) and Ashley Spicer, from the California Department of Fish and Wildlife, remove samples from tusk at the La Brea Tar Pits, in Los Angeles.  

In Southern California, there are two facilities that offer fascinating looks at the types of animals that roamed the land millions of years ago. The Western Science Center in Riverside County is home to 100,000 fossils and artifacts, all unearthed during construction of a nearby reservoir. The La Brea Tar Pits in neighboring Los Angeles County serves a similar purpose, storing a staggering 35 million prehistoric specimens discovered in and around the natural pits that continue to seep asphalt in the area.

Both facilities gladly open their doors to tourists and school field trips. Recently, they also welcomed two California Department of Fish and Wildlife forensic scientists, who traveled from Sacramento to collect samples of ivory tusks taken from Mammoths and Mastodons for a very specific purpose. Ashley Spicer and Kelly Carrothers came to collect the samples to take back to CDFW’s Wildlife Forensics Lab in Sacramento. The lab itself serves a number of purposes. In this case, the staff are collecting ivory samples for DNA testing and identification, under the auspices of a state law (AB 96) that makes it illegal to trade ivory or rhinoceros horn.

The Wildlife Forensics Lab maintains a species database that helps identify the origin of all kinds of ivory samples. The ability to pinpoint the source of any given ivory sample is critical when it comes to prosecuting criminal cases brought against suspected ivory traffickers.

“Mammoth and mastodon are species that are protected under AB 96 – you cannot commercialize them,” explained Spicer. “Examining the DNA allows us to identify the species of origin for any ivory-bearing species -- mammoth, whale, walrus, warthog or hippo. So, we can first distinguish whether a sample is ivory or not ivory, and whether it’s a fake or synthetic. If it is genuine ivory, then we can test it to see what was the species of origin.”

A key element of AB 96 was the closing of a loophole in previous laws. That loophole allowed the continued sale of tusk from mammoths and mastodons, because those animals were extinct. The exemption gave traffickers the chance to fraudulently claim that they were trafficking in legal material. Now that all forms of ivory trafficking are illegal – regardless of whether the species of origin is extinct – CDFW officials hope that an expanded DNA database will be the key to shutting down the ivory trafficking trade in California.

“The laboratory capability we have today helps us differentiate between ivory taken from an elephant that was poached in Africa within the last few years vs. ivory that was from an extinct species like a mammoth or a mastodon,” said Captain Patrick Foy of CDFW’s Law Enforcement Division. “This is huge for us – (now) we can actually prosecute these cases and convict these criminal poachers, to make the cases we couldn’t make 10 years ago,” said Foy.

CDFW is particularly grateful for the opportunity to obtain samples from the two Southern California facilities noted for their extensive fossil collections. “To be able to work with them (Western Science Center and La Brea Tar Pits) is a really exciting collaboration,” said Spicer. “These samples will be used for forensic testing methods, and ultimately for forensics case work that will help preserve some of our most precious natural resources.”

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CDFW Photos. Forensic Specialists Kelly Carrothers (l) and Ashley Spicer, from the California Department of Fish and Wildlife, examine tusk at the Western Science Center in Riverside County.

A healthy steelhead trout surveyed at Pescadero Creek Lagoon Complex in 2017


The aftermath of a winter sandbar breach 2014. These nearly annual breaches resulted in large die-offs for the lagoon’s steelhead.


A manual breach of Pescadero Creek Lagoon Complex. Managed breaches of the lagoon can prevent fish kills caused by turbulent natural breaches. Photo Courtesy of UC Davis School of Veterinary Medicine

There’s a dichotomy in the way Pescadero Creek Lagoon Complex in coastal San Mateo County has both supported—and been detrimental to—steelhead trout for much of the past 25 years.

On one hand, the lagoon complex—the largest tidal marsh between Elkhorn Slough and the San Francisco Bay estuary—boasts high growth rates for Central California Coast Steelhead. The lagoon system allows the species, which is federally listed as endangered, to reach a size that increases their likelihood of surviving at sea. Steelhead also use the system for juvenile rearing and resting during migration.

On the other hand, nearly every year since the mid-1990s, the lagoon faced harsh fall/winter sandbar breaches that filled the system with oxygen-depleted water and spread toxic sediment produced by the breakdown of organic matter like plant material in the absence of oxygen.

These breaches often resulted in large die-offs for the lagoon’s steelhead population. Historically, population estimates have reached as many as 17,000 steelhead rearing into the fall.

“It was a one-two punch where fish faced lack of oxygen and got hit with harsh toxic compounds. It was really unfortunate because the lagoon system works so well to grow steelhead, but we were losing the production every year,” said District Fisheries Biologist Jon Jankovitz.

Efforts to actively manage breaches began in 2012, but were stalled in 2014 and 2015 when the steelhead population was diminished due to drought conditions. In 2015, the California Department of Fish and Wildlife (CDFW) and the National Oceanic Atmospheric Administration (NOAA) partnered with the Department of Parks and Recreation (DPR), which owns much of the land associated with the complex, in adopting a monitoring and management plan.

In 2016, a significant fish kill caused by a turbulent sandbar breach prompted further action. CDFW, NOAA and DPR resumed active management to improve water conditions and prevent the deadly breaches.

The restoration team installed a sandbar dam at a major channel to slow the release of oxygen-depleted water and sediment into the system. Staff also preemptively manually breached the lagoon mouth on occasions when they anticipated a harmful natural breach.

Jankovitz conducts weekly water quality monitoring and twice-monthly dry-season fish sampling to inform management decisions. He produces an annual report on the health of the steelhead population and a summary of seasonal water quality transitions.

So how has active management faired? There hasn’t been a significant fish kill since 2016.

“We’ve saved the steelhead population for the last couple of years. We’re fortunate for the success we’ve had so far,” said Jankovitz.

Another mark of success has been the documented presence this year of sexually mature holdovers, meaning steelhead that were reared in the lagoon for two seasons even though they were large enough to smolt (i.e. migrate to sea).

“This obviously couldn’t happen if there was a fish kill the year prior. These holdovers represent a life history strategy that may fill in gaps during down reproductive years or periods of poor ocean conditions,” said Jankovitz.

There’s a long-term restoration plan in the works which would likely involve structural changes, such as relocating culverts and breaching levees, to alter the dynamics of how much tide flows in and out of the system. The plan includes a sediment removal project that was implemented in 2019 to increase fish passage.

Ultimately, CDFW and DPR would like to keep the system thriving without active management. “We don’t love breaching the lagoon manually because it can be stressful for fish and other aquatic species,” Jankovitz said.

Meanwhile, fostering an environment in Pescadero Creek Lagoon Complex that supports a large population of fast-growing steelhead continues to be top priority.

“Aside from being a native California species with a long history of recreational and angler use, steelhead are a great biological indicator of the health of streams and lagoon systems. The ecology of these systems would likely fall apart without them,” Jankovitz said.

Photos courtesy of CDFW District Fisheries Biologist Jon Jankovitz and the Bodega Marine Lab at University of California, Davis. Top Photo: District Fisheries Biologist Jon Jankovitz with a healthy Pescadero juvenile steelhead.

Media Contact:
Ken Paglia, CDFW Communications, (916) 322-8958

Faded black and white photos are all that’s left of the Owens River Gorge’s glory days as a trophy brown trout fishery. Biologists expect the fish to make a comeback following near-annual pulse flows that begin in September to improve habitat.




CDFW crews electrofish the Owens River Gorge two times per year to assess the health of the river’s brown trout.

From boom to bust to decades of angler indifference, few California fisheries have experienced such wild swings of fortune as Mono County’s Owens River Gorge.

The latest chapter in the long saga of the Gorge unfolds this month when the Los Angeles Department of Water and Power (LADWP) sends a relatively brief burst of water known as a “Channel Maintenance Flow” down the 10-mile stretch of river between the Upper Gorge Power Plant and Pleasant Valley Reservoir to benefit fish habitat.

From Sept. 9 to Sept. 17, water flows will rise from the relatively placid 35 to 55 cubic feet per second (cfs) typical in the Gorge to 680 cfs before gradually ramping back down. Access to the Gorge will be closed by LADWP during the nine-day “pulse flow” event for public safety.

The temporary boost in water flow represents the successful resolution of decades of legal battles involving LADWP, Mono County and CDFW. The high flows are expected to breathe new life into the Owens River Gorge ecosystem and its once-storied brown trout fishery. Court settlements mandate the pulse flows continue almost annually -- 18 out of every 20 years.

The flows are intended to replicate seasonal scouring that occurred naturally in the Gorge long before dams, power plants and water diversions were constructed in the last century. In fact, these alterations dried up the Owens River Gorge from 1953 to 1991 until years of litigation restored some minimal flows and attempts to restart a once-fabled brown trout fishery.

The Owens River Gorge is paradoxical – so close yet so far away. Just northwest of Bishop and within sight of Highway 395, it is difficult to access with limited and steep trails to reach its waters 500 to 900 feet below the rim. Since water returned to the Owens River Gorge in 1991, it has been more popular with hikers and rock climbers than trout anglers.

It was a much different story prior to the construction of the Long Valley Dam in 1941, which created Crowley Lake, and the subsequent addition of a number of power plants along the stretch of river. Before then, the Owens River Gorge was a destination brown trout fishery with a worldwide reputation. So good was the fishing it was one of the few waters in California with limits based on weight – 25 pounds plus one fish per angler per day.

CDFW Environmental Scientist Nick Buckmaster is based in Bishop and conducts twice-yearly electrofishing surveys in the Gorge along with macroinvertebrate sampling.
“Right now, the fish populations are pretty stunted,” Buckmaster said. “We just don’t have large brown trout in the Gorge anymore.”"

The Gorge is home almost exclusively to wild brown trout and the populations are high. Buckmaster estimates between 1,500 to 5,000 trout per mile, numbers that compare favorably to many blue-ribbon trout fisheries in the state.

“The problem is they are all small. Their growth really slows down around 5 inches, and most of the fish in the Gorge are less than 8-inches long. Their growth really plateaus,” he said. “By the time they get to 8 inches, they are geriatric fish.”

Buckmaster explained that brown trout undergo an important life change once they reach between 8 and 14 inches in size. They mostly stop eating aquatic insects and transition into apex predators, preying on other fish and just about anything else of substance they can eat. The diet change leads to rapid growth and turns them into a prize for any trout angler skilled enough to catch them.

Plateauing at 5 inches, however, most of the brown trout in the Owens River Gorge never reach that important developmental milestone or achieve it only toward the end of their lives.

“If you want big brown trout, they need something to eat,” Buckmaster said. “And they usually need a lot of something to eat.”

CDFW fisheries biologists expect the pulse flows to provide just that by dramatically altering the ecosystem. The big burst of water will scour pools and restore the deep-water holding and ambush habitat needed by large brown trout. The flows will flush out years of accumulated sediment, exposing gravel beds critical for trout breeding while fostering a broader diversity of aquatic life than what’s present in the Gorge today.

Mayflies and stoneflies are largely absent from the ecosystem, and caddisflies – safely encased and underneath rocks in their larval stages – provide a limited food source. Small populations of native Owens suckers exist in the Gorge. Their numbers are expected to grow with an increase in aquatic insect life following the pulse flows, incidentally providing important forage for growing brown trout.

The high waters will inundate and benefit riverside riparian growth, offering shade and cover and additional insect habitat. The flows also are expected to flush out invasive  New Zealand mud snails that have infested the Gorge over time. The snails provide little benefit to fish and are a source of competition for other macroinvertebrate life.

Buckmaster said biologists could see positive changes in the Gorge as quickly as three months after the flows. And bigger brown trout could start turning up in Buckmaster’s electrofishing surveys – and at the end of anglers’ lines – as early as next year.

CDFW Photos. Top Photo: CDFW scientific aids Christi Kruse and Emma Hewitt identify some of the macroinvertebrate life taken from the Owens River Gorge.

Rock Creek, where Shasta Crayfish were released by hand July 15.


Shasta Crayfish await delivery into their new home in Rock Creek. The Shasta Crayfish is a small- to medium-sized crayfish found only in northeast California.


Establishing populations of Shasta Crayfish in suitable water bodies that are inaccessible to invasive crayfish is the central effort in conserving the species.


The mix of 28 Shasta Crayfish introduced into Rock Creek included both juveniles and adults of varying sizes.

A 20-year, multiagency effort to find a safe haven for California’s only remaining native crayfish culminated recently with the release of 28 Shasta Crayfish (Pacifastacus fortis) into a restored section of Rock Creek in Shasta County.

The Shasta Crayfish has been in decline and under assault for decades from the pervasive, nonnative, invasive Signal Crayfish (Pacifastacus leniusculus), which not only outcompetes it for food and habitat but renders Shasta Crayfish females largely infertile through interbreeding. Found only in northeastern California, the Shasta Crayfish was listed as an endangered species by both the state and federal governments in 1988.

It was all smiles and optimism for a brighter future July 15, however, with the release of the 28 adult and juvenile Shasta Crayfish into a formerly dry, meadow portion of Rock Creek on property owned by Pacific Gas and Electric Company. That portion of Rock Creek, just six-tenths of a mile long, now flows with a reliable supply of cool, clear water with habitat enhancements that include rock clusters and riparian plantings.

Restoration of Rock Creek was completed in 2016 through a partnership with PG&E, CDFW, the U.S. Fish and Wildlife Service and the biological consulting firm Spring Rivers Ecological Sciences LLC.

Spring Rivers scuba divers collected Shasta Crayfish from the bottom of nearby Crystal Lake in June. Crystal Lake is believed to hold the most genetically robust population of Shasta Crayfish left in the wild but a population that’s also in decline as a result of the invading Signal Crayfish. The Shasta Crayfish were quarantined for 42 days before release into their new home.

Key to the Shasta Crayfish’s recovery as well as its biggest obstacle is establishing populations in waters inaccessible to the invasive Signal Crayfish. The refuge at Rock Creek was 20 years in the making by the time the site was identified, project proposals prepared and approved, permits secured, partnerships formalized, restoration work completed and the Shasta Crayfish translocated last month.

Restoration of the creek involved major construction removing a diversion dam upstream and rerouting a pipeline that supplied CDFW’s Crystal Lake Hatchery with water downstream. The location was deemed ideal as CDFW’s fish hatchery would block any Signal Crayfish in Crystal Lake from moving up into the restored portion of the creek.

In their new Rock Creek refuge, the Shasta Crayfish will be closely monitored. The hope is that they can serve as a sustainable, genetically diverse source population for future introductions.

CDFW Photos. Top Photo: Divers carefully released Shasta Crayfish by hand into their new home July 15. Prior to release, biologists measured and recorded their size and other data.

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Media Contact:
Peter Tira, CDFW Communications, (916) 322-8908

A tagged Amargosa vole. (National Geographic stock photo)


The “soft release structures” built for the voles were constructed in their natural habitat, giving the captive-bred animals time to adjust to the outdoors. (Photo courtesy of UC Davis School of Veterinary Medicine)
 

Wildlife veterinarians recently hit an important milestone in their collective efforts to conserve a tiny endangered mammal native to the Mojave Desert. The population of Amargosa voles (Microtus californicus scirpensis), restricted to one small town in Inyo County, is now perilously small, due to habitat destruction, climate change and water diversions created to benefit humans. With much of the voles’ natural habitat now decimated, scientists estimate that fewer than 500 currently exist in the wild. (Read the original California Department of Fish and Wildlife Science Spotlight on Amargosa voles).

Co-led by CDFW Wildlife Veterinarian Dr. Deana Clifford and UC Davis Veterinarian Dr. Janet Foley, the Amargosa vole recovery program started in 2012. After the population became nearly extinct in 2014, a captive breeding program was launched at the UC Davis School of Veterinary Medicine as a last-ditch effort to save these tiny creatures, which are a key link in the food chain in their native habitat.

Since the breeding program’s inception, 364 voles have been born and weaned. Several small-scale trial releases have been attempted over the last few years, leading the scientists to identify a clear problem: the animals raised in captivity didn’t necessarily know how to behave in the wild. “The colony animals were a little pampered,” said Foley, referring to the first few trial releases. “They didn’t seem to have the skills to thrive on their own.”

So how to teach a pampered vole to fend for itself? The team members tried several approaches, finally solving an important piece of the puzzle last month. The key was to introduce captive-bred animals to their wild counterparts – and let the former learn from the latter.

The team chose to pair six captive males from the facility at UC Davis with six wild caught females. The voles were introduced to each other for 10 days in temporary indoor cages in Shoshone Village to see which pairs appeared compatible for mating.

Once voles had established pairs, they were moved outdoors. Large dog runs were carefully constructed in their marshland, over the native bulrush that provide shelter and food for the voles. Each run was lined with hardware cloth in order to contain the voles and keep out predators (including coyotes, bobcats, snakes, numerous bird species, bullfrogs, house cats and stray dogs).

For the next 21 days, the new vole pairs continued to get to know each other. Project staff used pit tags – basically telemetry microchips – to monitor their movements and to ensure that they were thriving.

“We used an antenna array around the feeding station, which connects to a computer, so we could watch how they move,” Foley explained. “Most of the time they’re under the bulrush so you can’t see them with the naked eye … but we were amused to see that they’re really not that shy. One male built a tunnel in his natural habitat, but when staff was nearby, he would come out and look right at us before he grabbed food and went back in.”

At the end of 21 days, the kennel doors were opened, allowing the voles to venture out on their own. Foley says that the team was somewhat surprised to see that the pairs generally continued to come and go from the kennels, demonstrating a comfort level with the makeshift shelter. More importantly, at least one of the pairs produced a litter, and several of the other females may be pregnant.

At some point, the team will remove the kennels entirely, at least until the next captive release occurs, likely sometime next spring or summer.

Foley said that she views the July release as a rousing success – not just because the animals are thriving, but because of the body of knowledge the team learned from this experience. “It was really important for us to learn that the colony animals could learn survival skills from their wild counterparts,” she explained. “It was a gamble, and the fact that it worked is so exciting.”

The team will continue to use this technique for the foreseeable future. Ultimately, the goal is to create sustainable populations of Amargosa voles in several different areas. “If there’s a big fire, it could wipe out every marsh in the area,” Foley says. “Our work – and the techniques we are working to perfect -- will help ensure their survival.”

The captive breeding program is one part of a larger joint effort between agencies, universities and nonprofits to save the Amargosa vole. “Together with our partners at the US Fish and Wildlife Service, BLM, UC Davis and UC Berkeley, Shoshone Village and the Amargosa Conservancy, we are conducting habitat restoration, translocations, genetics and health monitoring and community engagement,” Clifford added. “What we’ve learned here not only helps voles, but also helps conserve the other species that rely on these fragile desert marshes.”

Photos Copyright UC Davis School of Veterinary Medicine. Top Photo: One of the recovery team staff members monitoring the vole’s outdoor enclosure during the introductory period. (Photo Courtesy of UC Davis School of Veterinary Medicine)

Media contacts:
Kirsten Macintyre, CDFW Communications, (916) 322-8988
Trina Wood, UC Davis Communications, (530) 752-5257