Science Spotlight

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  • October 26, 2018

Several people wearing waders in streambed holding nets in water
CDFW staff and volunteers set a one-day record of 1.5 million eggs collected on the Little Truckee River earlier this month.

People holding white net in water with several kokanee salmon in net
CDFW staff and volunteers use seine nets and electric fishing techniques to corral and capture adult Kokanee salmon.

Several people wearing waders holding nets in streambed. Boat and trees in background.
Volunteers from the California Inland Fisheries Foundation, Inc. and Kokanee Power help CDFW personnel capture Kokanee salmon.

Each October, conditions permitting, CDFW staff and volunteers from the California Inland Fisheries Foundation, Inc. and Kokanee Power descend on the Little Truckee River, just upstream from Stampede Reservoir near Truckee, and get to work on the annual Kokanee Egg Take.

Using seine nets and electrofishing techniques to corral and capture adult Kokanee Salmon, staff and volunteers then collect eggs and milt (fish semen) add them together in specific ratios to complete the spawning process. The fertilized eggs are carried to an egg care station on the side of river where they are measured, enumerated, disinfected and finally placed in containers to be transferred to the San Joaquin Hatchery.

Staff at San Joaquin Hatchery incubate, hatch and care for the early-life stages of the resulting baby salmon. Some fertilized eggs are shipped to other CFDW hatcheries for hatching and rearing. Resulting fingerling fish are stocked to several approved waters in the state to provide recreational angling opportunities.

“By all accounts, this year set the one-day egg take record of 1.5 million eggs,” said Roger Bloom, CDFW’s Inland Fisheries Program Manager. “This was a collective effort from our scientists, hatchery staff and stakeholders that culminated into actions in support of fisheries across the state. Given the magnitude of eggs taken on that record day, it took a non-stop effort of over 23 straight hours to get the job done, which highlights the dedication and resolve CDFW personnel have -- especially the hatchery staff who now will care for these eggs that will eventually grow to be little salmon!”

Kokanee Salmon were introduced into California waters to provide diverse recreational angling opportunities for anglers and have become an extremely popular sport fish. They are typically smaller than the landlocked Chinook Salmon, with an average size of about 12 inches. This summer, CDFW will release the Kokanee Salmon fingerlings that emerge from this collection effort into lakes and reservoirs throughout the state.

The landlocked version of the Sockeye Salmon, the Kokanee (pronounced coke-a-nee) Salmon spends its entire life in fresh water. Instead of migrating to the ocean, adult Kokanee Salmon inhabit large lakes before returning to their natal streams or gravelly shorelines to spawn. Like all Pacific salmon, Kokanee die after spawning, the whole life cycle taking from two to four years.

CDFW Photos. Top Photo: Volunteer holds a Kokanee salmon during work on the Little Truckee River.

Categories: Wildlife Research
  • October 19, 2018

Closeup shot of salmon fin
Close-up of adult spring-run Chinook salmon dorsal fin.

Close up shot of salmon with mouth open wide while held in hand
Adult spring-run Chinook salmon inform river restoration decisions by their habitat use and preferences.

Man wearing khaki colored waders, grey short sleeve shirt, orange vest and green CDFW baseball cap standing in water bent over holding salmon. Two other people standing in background.
Adult spring-run salmon are carefully selected for release based on their sexual maturity.

Salmon with blue tracking device held above white net over water
Spring-run Chinook salmon released into the San Joaquin River are outfitted with three tags including a colored T-bar tag for visual identification.

Fresno County may seem an unlikely setting for salmon restoration and research, but some of the California Department of Fish and Wildlife’s (CDFW) most ambitious work with salmon anywhere is taking place in the heart of the parched Central Valley.

Since September, CDFW fisheries biologists have been spawning spring-run Chinook Salmon broodstock in the shadow of Friant Dam on the San Joaquin River. This season, CDFW staffers spawned 100 mature females that ranged in age from 3 to 6 years old  producing about 290,000 eggs.

It’s all part of an unprecedented, multiagency effort to restore an extinct, spring-run Chinook Salmon run to the San Joaquin River that is happening alongside river restoration efforts to make the river more salmon-friendly for a fish listed as threatened under both the state and federal Endangered Species Act.

Historically, spring-run Chinook Salmon were the most abundant salmon species in the Central Valley. Today, there are so few fish broodstock used for spawning comes from eggs collected at CDFW’s Feather River Hatchery in northern California. Meanwhile, construction is underway on a spring-run Chinook Salmon hatchery at the base of Friant Dam to support future runs of San Joaquin River salmon. The hatchery is scheduled to be completed in 2019.

During spawning, each female is crossed with four males to maximize genetic diversity. Samples of ovarian fluid are collected and sent to the CDFW’s Fish Health Lab for virology and bacterial analyses. Any egg lots determined to be potentially infected with pathogens are excluded from CDFW’s captive rearing program.

In June and August, 179 captive-reared adult fish – 59 females and 120 males – were released into the San Joaquin River to monitor what parts of the river the salmon prefer for holding and natural spawning.

Prior to release, each fish was outfitted with three tracking devices – an electronic passive integrated transponder (PIT) tag for individual identification, a colored, T-bar tag for visual identification, and an acoustic transmitter so their movements in the river can be monitored and recorded. Their habitat use and preferences inform river restoration efforts.

Spring-run Chinook Salmon spawn in the fall from mid-August through early October. So far, biologists have found 37 constructed redds – or salmon nests – in the San Joaquin River indicating some of the released salmon found enough cool water in the heavily damned and diverted river system to survive the Central Valley’s furnace-like summer and are now actively spawning in the river.

CDFW Photos by Travis VanZant. Top Photo: Prior to their release into the San Joaquin River this past summer, adult spring-run Chinook salmon were outfitted with acoustic transmitters so their movements in the river can be monitored and recorded.

Categories: Wildlife Research
  • October 12, 2018

Trail cam photo of black bear in wooded area approaching barbed wire fence
Researchers built 90 hair-snare stations designed to pull a small hair sample from black bears that cross the snares.

Map with legend
The Warner Mountains Black Bear Project study area (blue boundary) and layout of hair-snare grids (yellow squares) in northeastern California. The upper-left inset shows the southernmost hair snare grid and layout of hair-snare locations (red circles). Density estimates and information on habitat from within the 10 grids will help researchers estimate overall black bear abundance across the entire study area.

California’s black bear population is healthy and growing, with an estimated 35,000 animals, up from an estimated 10,000 to 15,000 in 1982. But how do wildlife biologists determine these figures – and why are they important?

Deep in the Warner Mountains in Lassen and Modoc counties CDFW is just completing the first year of a study of black bears. The lead scientist, Steffen Peterson, explained that anecdotal evidence in recent years – including increased bear sightings by both field scientists and everyday citizens, as well as an increased number of requests for depredation permits due to bear-human conflicts – seemed to indicate that the population of black bears in the Warner Mountains was booming and this area would be ideal for scientific research.

According to Peterson, the two primary objectives of the Warner Mountains Black Bear Project are to estimate black bear abundance in the study area and to determine how black bears use the landscape. This kind of information on black bear demography and space use is essential for wildlife managers to make scientifically sound bear management decisions for this region of California.

CDFW is using a genetic capture-recapture method to estimate the population size. Usually, this involves physically capturing an animal, marking it in some way and releasing it. But this particular study achieves the same goal with non-invasive techniques – specifically by using hair snares, which cause relatively little stress or harm to the animals. Hair snares have been used on many furbearing species to determine presence, to calculate a minimum absolute count of individuals present, or to estimate total population size by collecting a DNA sample from individuals without physically capturing the animal. Unique repetitive sequences, known as microsatellites, within the DNA sample serve as individual identifiers, making it possible to know when and where each unique animal was present.

In addition, because the DNA located within roots of mammalian hair can identify species, sex, and individuality, this genetic technique is ideal for researchers to estimate abundance as well as obtain information on demographics and genetic diversity.

Peterson, a CDFW scientific aid and a Humboldt State University graduate student, and other researchers built 90 hair-snare stations distributed across 10 sampling grids that that are designed to pull a small hair sample from bears that cross the snares.

The contraption consists of two parallel strands of barbed wire stretched around a cluster of three or more trees, one about eight inches off the ground and the other about 20 inches off the ground. This forms a barbed-wire “corral” in which researchers place a pile of logs drizzled with fish oil. The oil acts as an attractant to black bears, who have both a finely attuned sense of smell and a profound love of fish. At two thirds of the hair-snare stations, researchers placed a trail-camera to help verify the effectiveness of the snares at capturing hair samples when a bear is present. The trail photos also provide demographic (cub-adult ratio) information on bears within the study area.

“The use of hair-snares to collect genetic data for abundance and density estimates has become the gold standard for American black bear,” said Peterson. “The hope is for the bear to cross between the two strands of barbed wire, although some of our video footage from the trail cameras shows bears crossing – even jumping, in some cases –  over the wire. Because bears are big, robust animals, for the most part they pay little mind to the barbs and typically cross them, leaving us a nice big clump of hair. Bears are the ideal critter for hair-snares in this way.”

Although Peterson stressed that it is much too soon in the study process to draw conclusions about the number of black bears living on the grid, initial results indicate that, at a bare minimum, black bears are certainly roaming throughout the study area.

During a 50-day hair collection period that took place this summer, black bears were detected in all of the grids created in the study area that encompasses roughly 600 square miles of high desert terrain; researchers collected 469 samples of hair in all at 57 of the 90 hair-snare locations.

“Long story short, we are pleased by the amount of detections observed during our data collection,” Peterson said. “Good detections will strengthen our ability to estimate density within each grid which will allow us to more reliably estimate abundance off the grid – i.e., the Warner Mountain study area as a whole.”

Peterson is now set to begin the DNA analysis phase on the samples collected. This will allow him to determine precisely how many individual bears left hair behind (bears often leave more than one sample at a snare location and some individuals are repeat visitors), as well as information on gender and habitat use, including the movement of bears across the study area.

Next summer, project staff will capture and collar 12 adult black bear with research collars, which will record hourly GPS locations of the bears as they move across the landscape, providing information on how they use the landscape, including seasonal habitat preferences and, during the winter hibernation period, where bears den.

“This information will greatly improve our knowledge of how bears use these high desert ecosystems, characteristic of the Great Basin, and guide future land management in this region,” Peterson said.

The project is expected to continue for another two to three years. ###

CDFW Photos. Top Photo: Emily Monfort, a CDFW scientific aid, carefully removes black bear hair from barbed wire at a hair-snare location. The DNA from this clump of hair will be examined in the laboratory to determine the sex and genetic identity of the black bear that crossed this wire.  Photo credit Korrina Domingo (CDFW).

Categories: Wildlife Research
  • October 5, 2018

Panoramic view of dry grassland and blue sky.
Panorama of Summer Lake

Smiling woman wearing green USGS hat and shirt holding collared goose
USGS employee holding goose

Wetland with tule grass in foreground and mountains in background.
Summer Lake

Waterway with mountains in background
Summer Lake

Woman in green shirt and pants wading thigh-deep in water holding net and surrounded by geese
Melanie in the water retrieving geese

partial view of white pickup truck with face in sideview mirror. Grassland and mountain in background
Melanie in sideview mirror

Woman wearing green long sleeved shirt, glasses, and braids holding collar around neck of goose held by person wearing a brown jacket.
Fitting the collar

Person wearing brown sweatshirt holding collared goose. Goose has bill around person's index finger.
A finger nibble

Every September, California Department of Fish and Wildlife waterfowl biologist Melanie Weaver sets off on an unusual business trip. She packs up a trailer with huge nets, wire, rockets, crates and a number of VHF collars. She makes the seven-hour drive to Summer Lake, in southern Oregon’s high desert country, and settles in for a waterfowl capture project of indeterminate length. Her quarry is Anser alibifrons elgasi — the Tule white-fronted goose. Her goal is to capture, collar and release these huge, cackling birds until she runs out of collars.

Tule geese are one of two sub-species of white-fronted goose — also known colloquially as specklebelly geese, or “specs,” by hunters. The other sub-species of white-fronted goose, Pacific white-fronted, are plentiful, numbering about 700,000 in the Pacific flyway. But the Tule goose is far less common. Weaver estimates there are only 15,000 to 16,000 Tules.

Monitoring goose populations — particularly Tules — is a high priority for CDFW, as regulations are tied to the less numerous species. Currently, California regulations dictate that the hunting season for white-fronts on the west side of the Sacramento Valley closes on Dec. 21. This is to minimize harvest on Tule geese.

“They are right in the middle of a popular hunting area for Pacifics, so we have to be proactive,” Weaver explained. “If we saw the population decline significantly, we’d have to consider closing the season for all white-fronted geese. We want to avoid that.”

But why would the California Department of Fish and Wildlife be trapping geese north of the state line? One reason is logistics —Tule geese begin their southward trek from Alaska in mid-August or thereabouts. They’re heading for the Sacramento Valley, and Summer Lake Wildlife Area is a major stop over along the migration route. As they move further south into California, Tule geese mix with their more common cousins, the Pacifics. “We’ve tried to capture them in and around the Sacramento National Wildlife Refuge Complex before, and we end up expending a lot of effort just for a handful of Tules caught,” Weaver explained. “So the Oregon Department of Fish and Wildlife suggested moving our capture effort to the Summer Lake Wildlife Area. It’s largely only Tule geese coming through this time of year.”

And that’s the other reason — this partnership between the waterfowl programs from neighboring states illustrates the importance and strength of the Pacific Flyway. Alaska, Canada, Washington, Oregon and California all have a stake in ensuring the conservation of the species that traverse their lands and use their waters. ODFW doesn’t just offer up their land as a banding site. They also provide lodging for Weaver, typically split the cost of the radio collars, and supply labor for the duration of the project, no matter how long it takes.

Weaver’s ODFW counterpart, waterfowl biologist Brandon Reishus, was in it for the long haul right alongside Weaver. On a chilly Monday morning in mid-September, only just a week after they laid out the nets, they hit the jackpot. On that particular day, Reishus was crouched in the blind, using a scope to scan for incoming flocks, while Weaver sat nearby in a pickup truck. They waited and watched for a few hours, keeping in touch by radio, before Reishus spotted his opportunity. After a quick heads up to his Californian counterpart, the Oregon biologist pressed the detonation button, launching the pre-set rockets a quarter mile away. In the blink of an eye, the 60-foot-long net sailed over the unsuspecting birds as they blissfully churned up grit from the water. Both biologists then jumped into the truck and raced to the site, where they untangled the geese and put them into crates for transport to the Summer Lake Wildlife Area shop. The final count on this particular morning was 14 birds; a small number was all that was needed to complete the marking effort for this year as an earlier capture resulted in 44 birds.

The geese were given a little time to settle down before the processing began. Each bird was sexed and the bills measured. Although Weaver and Reishus can typically identify their catch just by the size and color (Tules are larger and darker than Pacifics), scientific measurements are essential for definitive identification.

The birds were also weighed before they were banded and collared. The collars will enable the biologists to obtain a population estimate on the wintering grounds, using a mark resight method. This and other data obtained from the bands will be used to make future management recommendations.

In the early afternoon, Weaver and Reishus drove back to the exact spot where the net was deployed just hours earlier. On the count of three, all the crates were opened at the same time, and the geese noisily rushed out, spreading their wings and re-forming their flock as they raced away.

As Weaver and Reishus affixed the last of the VHF collars on this particular Monday, they marveled at the unusually early conclusion of this years’ trapping effort. Sometimes it takes a full two weeks to use up their supply of collars. Once again, the team effort paid off. And even as they packed up their equipment from the Summer Lake Wildlife Area and prepared to head their separate ways, they were making plans to meet up again in a week, for a Pacific Flyway Study Committee meeting in Arizona.

“It’s such a valuable partnership,” Weaver said. “We look at the big picture, and we all work on solutions together.”
 
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CDFW Photos. Top Photo: weighing a goose.

Categories: Wildlife Research