Science Spotlight

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 long, wet winter has been good for Junction Reservoir and CDFW’s Kamloops rainbow trout that live there.


The June Lake Marina graciously offered up its net pens to CDFW’s Kamloops rainbow trout program when the drought forced CDFW to rescue its brood stock from a shrinking Junction Reservoir.


CDFW hatchery staffers Jimmy Sparks, left, and Drew Klingberg prepare to sex and sort Kamloops brood stock for later spawning, separating males from females as well as those females ready to spawn immediately versus those that need more time to ripen. The fish are returned to Junction Reservoir after spawning.


The offspring from these Kamloops will be raised at CDFW’s Fish Springs Trout Hatchery and stocked by airplane as fingerlings into backcountry waters across the state approved for trout stocking.


Resplendent in their spring spawning colors, Kamloops rainbow are raised and bred for their hard-fighting ability and wild nature that allows them to thrive in California’s remote backcountry waters and provide a thrill for anglers who catch them.

Junction Reservoir in Mono County is CDFW’s brood lake for the Kamloops rainbow trout, a hard-fighting strain originally from the Kamloops region of British Columbia.

The 20-acre lake sits on a private cattle ranch off-limits to fishing. It provides a secluded setting for the brood stock, whose progeny are used almost exclusively for the aerial stocking of backcountry waters throughout the state.

“We try to keep them raised in a more wild condition so they do better in the wild,” said Hot Creek Trout Hatchery Manager Mike Escallier. “They are a really fun fish to catch. They jump a lot. They will jump 3 feet out of the water when you hook one.”

And Junction Reservoir has never looked better. This spring, the lake was filled to the brim after a long, cold, wet winter. Near the mouth of the lake’s one small inlet, Kamloops were staging for a spawning run, their feisty nature on full display in the clear waters, breaking the surface occasionally and fighting each other over territory.

Kamloops further up the inlet were blocked from moving upstream by a concrete and metal trap. That’s where CDFW’s hatchery staff collect and sort the fish each spring, spawning them manually to produce the offspring that will be deposited as fingerlings this summer by airplane into backcountry waters approved for stocking.

The entire scene is a welcome sight after California’s drought nearly collapsed CDFW’s backcountry fish-stocking program. During the darkest days of the drought, the small inlet feeding into Junction Reservoir dried up. Combined with the years-long shortage of rain and snow, Junction Reservoir withered to about half its size. In 2013, CDFW conducted an emergency fish rescue to save about 2,000 of the brood fish and its backcountry trout stocking program altogether.

The rescued fish were relocated to CDFW trout hatcheries and other nearby waters for safe-keeping. The owners of the June Lake Marina provided a major assist, offering up some of their net pens on June Lake to CDFW and its Kamloops at no charge. The June Lake net pens continue to hold some Kamloops, which CDFW spawns each spring until the program transitions back fully to Junction Reservoir and CDFW’s Fish Springs Trout Hatchery south of Big Pine where the baby Kamloops are raised.

CDFW returned brood fish to Junction Reservoir in the spring of 2017 following a wet winter and heavy snowpack. CDFW is rebuilding production toward its annual goal of collecting and fertilizing 1.4 million eggs. Some of the offspring are put back into Junction Reservoir to add genetic diversity and different age classes to the rebuilding brood population as no natural spawning occurs in the lake.

One benchmark hatchery managers and biologists are striving toward is the return of Kamloops to Crowley Lake, where more anglers will have a chance to enjoy them.

Before the drought wreaked havoc on CDFW’s Kamloops program, a portion of the Kamloops produced each year were allocated to Crowley Lake. While the backcountry trout are sterile – or “triploid” – the fish stocked into Crowley are “diploids” capable of spawning naturally.

“They spawn at different times than other strains of rainbow trout,” explained Escallier. “They give anglers fishing the creeks opportunity. They tend to be running up the creeks from Crowley right around the trout opener.”

CDFW Photos. Top Photo: The inlet to Junction Reservoir is blocked by a fish trap where CDFW hatchery employees catch fish in the spring for spawning.

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

The April 30 deadline to turn in California spiny lobster report cards is fast approaching – and CDFW needs your catch data!

The information collected from these is enormously helpful to CDFW scientists who monitor the harvest, amount of fishing effort and the gear used in the recreational fishery. Although CDFW has considerable information about the commercial lobster fishery from landing receipts and logbooks, there was very little reliable information on the magnitude of the recreational lobster catch and fishing effort prior to the launch of the lobster report card program.

CDFW first began requiring lobster fishers to fill out and turn in harvest report cards 10 years ago, in the 2008-2009 season. Persons taking or trying to take lobsters were required to possess, fill out and submit spiny lobster report cards at the end of the season.

By the 2013-2014 sport fishing season, CDFW rolled out a new spiny lobster report card system with new reporting requirements to improve the estimates of the recreational fishery harvest. The new reporting requirements included a non-return penalty fee if cards were not returned at the end of the season. Since then, card return rates have improved greatly. It could be argued that the new reporting requirements encourage more people to return their lobster report cards, which in turn has improved estimates of sport lobster catch and effort.

Results determined from report card returns after the 2017-2018 season showed a 50 percent return rate of more than 16,000 cards, compared to 22 percent (approximately 6,000 cards) after the 2008 season. In 2017-2018, more than 85,000 lobsters were reported kept versus nearly 48,000 reported in 2008. Based upon the numbers from 2017-2018, more than 171,000 lobsters were estimated taken by the recreational fishery. When added to the recorded commercial harvest for this season, recreational fishermen accounted for 31 percent of the entire California spiny lobster harvest for the season.

The cost for this year’s spiny lobster season report cards was $9.27 when purchased from CDFW offices, with a small (about 2%) surcharge applied when purchased from other vendors. Report cards are available in most places where sport fishing licenses are sold, including tackle shops and sporting goods stores, or can be purchased online. The funds raised by the sale of lobster cards are earmarked for CDFW projects, including those specifically focused on the lobster fishery.

Daily bag and possession limits are seven lobsters per person. No more than one daily bag limit may be taken or possessed by any one person unless otherwise authorized, regardless of whether they are fresh, frozen or otherwise preserved. This means that if you have a limit of seven lobsters at home, you cannot go out and get more lobsters until the first limit is disposed of in some way (eaten, given away, etc).

People often ask why commercial fishermen are allowed to use huge traps while recreational fishermen are restricted to using hoop nets. Many think this doesn’t seem fair, but CDFW is mandated by law to allow for the sustainable use of lobster by both the commercial and recreational fishing sectors. While our laws say that recreational fishermen are entitled to harvest for sport (and not subsistence use), commercial fishermen must make a living off the resource. The commercial lobster industry is highly regulated, with a fixed number of permits, and commercial fishermen are required to use traps with strict regulations concerning mesh size and escape ports that allow large numbers of sub-legal sized lobsters to come and go freely from traps. Recreational lobster fishing is considered a sport and not meant for subsistence.

CDFW would like recreational users to enjoy this resource. The number of recreational participants is not restricted, and hoop nets and diving are both very effective methods of recreational take. Finally, there are large productive areas that are closed to commercial lobster fishing but open to recreational lobster fishing, such as Santa Monica Bay, San Pedro Bay, San Diego Bay, the lee side of Catalina Island and many bays and jetties.

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Some interesting facts about these popular crustaceans: California spiny lobsters are believed to live 50 years, or more! The males have been recorded up to three feet long and weighing 26 pounds. Today, lobsters over five pounds are considered trophy-sized. For more information on spiny lobster biology, please check out our California Spiny Lobster brochure (PDF).

CDFW Photos.

Media contacts:
Carrie Wilson, CDFW Communications, (831) 649-7191
Kirsten Macintyre, CDFW Communications, (916) 322-8988

At Iron Gate Hatchery in Hornbrook, the fall 2018 spawning operation has just concluded. Iron Gate spawns both Fall-Run Chinook Salmon and Coho Salmon from the Klamath River. For Chinook, the hatchery staff manually collect the eggs and mix it with the milt immediately after the fish come into the facility. CDFW environmental scientists also collect heads from adipose fin clipped salmon, in order to retrieve implanted tags in the snout. The retrieved tags tell the biologists which hatchery the fish is from, and when it was released. They also collect scales, which enable them to determine the age of the fish.

For Coho Salmon, the process is a little more involved. The Coho are measured and samples taken, but the samples are sent off to a National Oceanic and Atmospheric Administration (NOAA) laboratory in Santa Cruz for analysis. While the samples are processing, the fish are kept in individually-numbered holding tubes at the hatchery. They will be spawned after the tissue analysis determines which fish are the best genetic match.

CDFW Photos

For more information about Iron Gate Hatchery, please visit: www.wildlife.ca.gov/Fishing/Hatcheries/Iron-Gate.

Media Contact:
Kirsten Macintyre, CDFW Communications, (916) 322-8988