Science Spotlight

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  • June 20, 2018

Birds eye view of waterways and land

Birds eye view of waterways and land masses

In the heart of California’s Sacramento-San Joaquin River Delta lies a 3,000-acre flooded island called Franks Tract.

Before humans diked and drained Franks Tract to grow potatoes, grains, asparagus and corn, the island was part of a vast freshwater marsh. Breaches in levees flooded Franks Tract in 1937, and farmers never reclaimed the island. Franks Tract today is a nexus point of many delta uses, ranging from duck hunting and bass fishing to fresh water supply for California cities and farms.

But the island is also a hot spot for invasive plants and predatory fishes, as well as a conduit for saltwater intrusion into waterways used to convey freshwater supplies to cities and agriculture in the Delta and other parts of California. For these reasons, Franks Tract is considered a strong candidate for partial restoration.

“Franks Tract is a microcosm of many of the larger problems pervading the inner Delta, said Carl Wilcox, Delta policy advisor to the director of the California Department of Fish and Wildlife. “Some native fishes are in serious decline, improving the quality of available habitat in the Delta and increasing resilience to drought and climate change could support their persistence and recovery.”

Various partners, led by CDFW, are proposing to restore about 1,000 acres of Franks Tract to tidal marsh. The proposed restoration is consistent with the Delta Smelt Resiliency Strategy, state goals for the Franks Tract State Recreation Area, and state water quality control plans for the San Francisco Estuary. The effort also aligns with the multi-agency Delta Conservation Framework and the Central Delta Corridor Partnership.

The proposed restoration could shrink waterweeds, grow fish food, create habitat for Delta smelt and other declining species, and prevent salinity intrusion into the south Delta. It may also improve recreational opportunities for residents and visitors.

Results of hydrodynamics modeling indicate the proposed restoration would provide more fresh water to the central Delta shielding regions upstream from ocean saltwater intrusion. A 2017 UC Davis survey documented year-round use of Franks Tract and surrounding channels by locals, visitors and researchers, and seasonal use by hunters, anglers and boaters. Many survey respondents were concerned about changes in access to the water and effects on the local economy and sport fishing, which is dependent on that access. The survey yielded useful information for the next, more detailed, planning and design round including a locally proposed alternative design.

“We will continue to work with stakeholders to not only address habitat and water quality priorities, but also enhance recreational and sport fishing opportunities,” Wilcox said.

A recently released report, Franks Tract Futures: Exploring Options for Multi-Benefit Restoration and Increased Resilience in the Central Delta Corridor, summarizes the technical studies and stakeholder input that’s been collected relative to the potential restoration of Franks Tract.

If approved for further development, the Franks Tract restoration proposal would enter a second phase of planning, design and environmental review with a target end date of December 2020.

CDFW Photos.

Categories: General
  • June 11, 2018

Man holding large cardboard box in front of man holding turkey.
Tim Hermansen of CDFW carries a turkey holding box to CDFW’s Levi Sousa while John Davis clears the net.

Person holding turkey while another person holds turkey foot against wooden post.
Derek Schiewek of CDFW holds a turkey while CDFW’s Laura Cockrell measures the tarsus.

Recent efforts to determine the number of turkeys on the Upper Butte Wildlife Area have been a net success.

CDFW staff and volunteers from the National Wild Turkey Federation (NWTF) began annual turkey banding efforts in 2015 to gather information about turkey demographics and movements to facilitate better management of the population and assess future hunting opportunities. Approximately a dozen volunteers and staff have since worked on this effort two months each year, in the late winter through early spring.

Captured birds are fitted with a numbered band, and their age, gender and weight are determined before they are released. The number of times a turkey is recaptured through ongoing trapping activities, or when a hunter returns a band to CDFW, provides data about the density and the movements of the birds. Approximately 20 wild turkeys have been captured each of the past four years, using air cannons that propel nets. Last year was the sole exception, as torrential storms resulted in zero captures because portions of the property were flooded and could not be traversed with trapping equipment.

“That year was very frustrating, but part of being a wildlife biologist is going with the flow,” recalled CDFW Environmental Scientist Laura Cockrell, who is involved in coordinating and facilitating wildlife surveys on the wildlife area.

This year, walk-in traps were used for the first time to supplement the traditional use of air cannons, and the final tally was 38 turkeys banded, increasing the total number banded over the course of the project to 88. This baseline data will inform decisions on how many turkey hunters will be allowed access to the wildlife area each spring.

“Our volunteers and all our staff are what makes this project successful,” Cockrell said. “Everyone completes a safety training so we can make sure the birds are handled quickly and carefully, and then it is a lot of ‘hurry up and wait’ during the trapping operations. If we did not have a dedicated crew on this project, it would not be successful. The walk-in traps allow staff to set up trapping operations in the morning, check the site throughout the day, and process birds as they are captured.”

Also appreciative of the banding efforts were turkey hunters, who had an extra “spring” in their step this year at the Upper Butte Wildlife Area.

The 2018 spring turkey hunts recently ended after 64 hunters who hunted on Upper Butte Basin harvested 35 turkeys. During the previous three spring seasons combined since spring turkey hunts began on the wildlife area in 2015, 133 hunters participated and 47 turkeys were harvested.

All the result of field conversations between CDFW staff and fall turkey hunters.

“During the fall turkey seasons some years back, hunters at the check stations would frequently ask us when we were going to offer a spring season, which we had not done before,” Cockrell said.

At the wildlife area’s Howard Slough and Little Dry Creek units, the problem was not a lack of turkeys but rather a lack of funding to hire staff to advertise, prepare, regulate and operate the extra hunts – and a lack of scientific data to support an extra hunting season.

A collaborative effort between CDFW and the NWTF solved that problem.

In 2014, NWTF applied for and received a state grant from the Upland Game Bird Stamp Fund. The grant proposal, which was spearheaded by NWTF District Biologist Kevin Vella, obtained five years of funding to support a seasonal coordinator position.

“This spring we had almost 1,800 applications for 144 open spots,” said Cockrell. “Our hunters really appreciate the opportunities that the spring turkey hunts provide. We frequently hear after a hunt what an amazing time they had out in the field and how much they enjoyed their time on the wildlife area. One of our hunters this season was so excited because he was able to harvest a nice turkey at his very first hunt!”

All photos © National Wild Turkey Federation, all rights reserved. Top Photo: Tim Hermansen of CDFW holds a turkey while Laura Cockrell of CDFW measures its beard with calipers.

Categories: General
  • May 31, 2018

Diver underwater in black diving suit holding underwater writing tablet underwater in kelp forest
WARC diver Shelby Kawana assesses habitat at one of the CDFW red abalone stocking sites located off the coast of southern California.

Diver underwater in black diving suit holding a large grid made from PVC pipes and wire in kelp forest
WARC diver Armand Barilotti assesses habitat at one of the CDFW red abalone stocking sites located off the coast of southern California.

Curled up octopus hiding underwater
Octopus are a top abalone predator and therefor pose a threat to newly stocked juvenile red abalone populations. Researchers catch and relocate octopus when they are found hiding in crevasses near stocking sites.

Abalone attached to a rock
A rediscovered stocked red abalone was found clinging to the underside of a rock during a one year post stocking survey.

Harvesting abalone for dinner used to be as fundamental to a Southern California lifestyle as fish tacos and flip-flops. But by 1998, a combination of overfishing and disease led to the closure of all abalone fishery south of San Francisco. By 2001, the white abalone was listed as an endangered species because populations continued to decline despite protection from fishing pressure. Population numbers are so low today that the only option for recovery is believed to be through a robust captive breeding and stocking program.

Scientists from the California Department of Fish and Wildlife (CDFW) White Abalone Recovery Project and their partners in the White Abalone Recovery Consortium (WARC) are working to bring back the iconic white abalone from the brink of extinction. Since 2016, CDFW and partners have been working to actively restore abalone populations through stocking of young captive-reared abalone. Successful stocking is the critical next step to reestablishing self-sustaining wild populations of this culturally and ecologically important mollusk. The early stocking studies have aimed to perfect the methods that will be used to restore wild white abalone populations in the future by using red abalone as a test case. Red abalone, a sister species of the white abalone, lives in the same deep kelp forest habitats, and their populations in Southern California have also been very slow to recover.

Every few months, scientific divers on board the CDFW research vessel Garibaldi wrestle into thick neoprene wetsuits and load heavy steel tanks onto their backs in order to check on the stocked abalone. As the divers descend deeper into the kelp forest, they enter the world of the white abalone. Sunlight streams through the towering giant kelp, briefly illuminating the shiny sides of the small fish taking cover in the kelp blades. Lobsters and octopuses are tucked into the crevices of rocks, and abalone and urchins shelter in the shadows. Many of those abalone are adorned with small brightly-colored numbered tags that identify them as the new additions to the neighborhood. After a few months in the wild, the stocked abalone can show an extensive amount of growth which speaks to the quality and abundance of resources in their new habitat.

Since restoration stocking began in 2016, the partnership has stocked close to 10,000 red abalone off the coast of southern California. These studies are helping scientists understand how stocked abalone interact with their new environment in the wild. Researchers are increasing the effectiveness of future stocking work by teasing out the risk factors that abalone face in their new environment. For multiple years after releasing the abalone, divers track the number and identity of each abalone, and assess the ecosystem health and predator abundances at each site. The divers also collect any abalone shells encountered to determine the effects of different predators at each site through time.

Octopuses, lobsters, sea stars and fish are all major predators of the young abalone, and care is taken to introduce the abalone during times of the year when the predators will be least abundant. All of the data from these early studies are aimed at lessening the risks that stocked abalone face, and to improve long-term growth and survival.

The WARC understands that abalone are at the heart of coastal California’s identity and culture. The return of red and white abalone to the wild marks the beginning of a new chapter in the love story between California and this amazing mollusk. This is true for the ecosystems that rely on them as well as for the humans that cherish them. Please stay tuned for updates on the lessons learned from these studies, and plans for upcoming white abalone stocking work!

For more information, please visit the following pages:

CDFW Photos. Top Photo: Newly tagged red abalone that are ready to be released into the ocean during a WARC stocking study in 2016.

Categories: General
  • April 24, 2018


Man in Department of Fish and Wildlife uniform on coastal cliff with succulent plant in hand
Wildlife Officer Pat Freeling replanting dudleya.

Man in Department of Fish and Wildlife uniform on vegetation covered cliffside with hand on succulent plant
Wildlife Officer Will Castillo replanting dudleya.

Last week, a team of California Department of Fish and Wildlife (CDFW) staff and volunteers spent hours working to replant than 2,000 Dudleya succulents that were seized after a poaching investigation. The plants were meticulously returned to the Mendocino and Humboldt county cliffs from where they were stolen weeks before.

The sheer volume of plants made it necessary to put a call out for help from volunteer botanists. The response was overwhelming. More than 20 succulent experts from the California Native Plant Society and U.C. Santa Cruz arboretum, along with National Parks Service personnel, assisted CDFW wildlife officers and seven environmental scientists on the replanting project. The replanted succulents will be monitored over the next week to ensure the greatest chance for survival.

CDFW Environmental Scientist Michael van Hattem calls Dudleya “the botanical version of abalone,” in the sense that they are a sensitive species, dependent on a very specific habitat. Without a concerted effort to reverse the effects of such a large poaching operation, he says, the ecosystem would be irreversibly damaged.

In March 2018, CDFW law enforcement officers uncovered an international conspiracy to strip the succulents from sea cliffs and ship them overseas to other countries, including Korea and China, where they are prized for decorative purposes. So far, there have been three significant poaching investigations. In the first case, prosecuted in Mendocino County, the subject was found guilty and fined $5,000. A second case is also currently pending in Mendocino County. 

The link opens in new windowthird recent case was out of Humboldt County, where wildlife officers seized well over 2,000 succulent plants from three suspects. Prosecution of that case is also pending. This week, the Humboldt County District Attorney’s Office released all but 10 of the plants from evidence to allow the team to replant them at the location where taken. 

“Our wildlife officers and partners have gone to extraordinary length to investigate and stop a new poaching threat in California,” said David Bess, Deputy Director and Chief of the Law Enforcement Division. “We can't think of a better project to work on through Earth Day weekend.”

CDFW Photos. Top Photo: Wildlife Officer Will Castillo replanting a Dudleya succulent.

Categories: General
  • April 20, 2018

Man in Department of Fish and Wildlife uniform standing in the bed of a truck shoveling rocks

Man in Department of Fish and Wildlife uniform standing in stream pouring rocks into stream from large bucket

Man in Department of Fish and Wildlife uniform crouching in stream looking at the water

Stream with rocks lining the streambed

California’s drought emergency was officially declared to be over last year, but its deleterious impact on fish habitat is still being felt in many parts of the state -- especially in arid parts of Southern California. In order to help offset these effects at one site in northern San Diego County, CDFW biologists and other staff recently toiled to create spawning beds for rainbow trout.

The Sweetwater River is a second-order stream located within Cuyamaca Rancho State Park. The underlying rock is granite, which, as it erodes, creates sand that accumulates in the low-gradient portion of the river. Previous surveys in the Sweetwater River revealed a lack of high-quality spawning habitat for the rainbow trout population, which was reduced by 70 to 80 percent during the recent drought.

Seeing an opportunity to restore habitat to this waterway, South Coast Region fisheries biologists came up with a plan to place suitable materials into Sweetwater for the rainbow trout to use for new spawning grounds. Beginning on March 20, CDFW Environmental Scientist Russell Barabe, scientific aids Joseph Stanovich and Ken Sankary and volunteer Mark Berlin worked in the hot sun and dry conditions to rehab the streambed. Using a nearby dry stream channel, the team shoveled hundreds of pounds of rocks and materials through mesh screens to remove fine sediment and sand and clean the rock, called cobbles, to make them ready for placement into Sweetwater River. All the rock had to be moved one bucket at a time and poured into pool tailouts (the downstream end of a pool where the water gradually shallows) to create spawning beds about three feet square for rainbow trout.

Though similar work has been done in northern California – specifically two larger-scale projects in the American and Sacramento rivers, which served as the inspiration for this project – it had never been done in this small a stream before.

This small but important project could increase the spawning success of a drought-reduced population in a stream with easy public access. If successful, this project could be used as a model for future habitat restoration activities in other small trout streams. The fisheries team’s work is an example of how our scientists put the mission of CDFW – to conserve California’s fish and wildlife resources for the use and enjoyment of the public – into action.

CDFW Photos. Top Photo: CDFW Scientists hauling buckets of rocks to create spawning beds for rainbow trout.

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Categories: General
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