Science Spotlight

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  • May 9, 2019

Closeup of man holding up fishLahontan cutthroat trout are a Crowley prize. In addition to natural spawning that occurs in the lake, CDFW plants the fish as fingerlings in the fall. By the spring opener, many like this fish are resplendent in their spawning colors.

Man in brown and beige CDFW uniform on boat bent over cooler with fish while holding a ruler in cooler. Jim Erdman conducts creel surveys to see how many trout CDFW planted last fall turn up on opening day. Fish 15 inches or longer are determined to be from last fall's stocking when they were planted as fingerlings.

Man in white t shirt, sunglasses and ball cap on beach in front of body of water holding up a fish with spots. Mark Risco from Temecula shows off the 20-inch brown trout he caught opening day at Crowley Lake. In addition to natural spawning, CDFW's Hot Creek Hatchery stocks thousands of brown trout each year, which are very popular with Crowley anglers.

Man wearing CDFW uniform, sunglasses, and green ball cap standing in dirt parking lot holding clipboard.CDFW volunteer Carl Ronk conducted opening day creel surveys at Crowley Lake along with CDFW Environmental Scientist Jim Erdman.

Mono County’s Crowley Lake is a destination fishery that attracts trout anglers of all kinds – bait fishermen, lure casters, trollers and fly anglers – throughout the state during its open season.

The sprawling lake, situated at 6,700 feet and covering some 5,300 surface acres in the Eastern Sierra, also represents a huge investment for CDFW. The nearby Hot Creek Trout Hatchery raises hundreds of thousands of rainbow, brown and Lahontan cutthroat trout for Crowley each year that provide the backbone of the quality angling experience. Many of the fish are stocked as fingerlings in the late summer or fall and grow rapidly in the invertebrate-rich environment. Some go on to spawn in the lake’s many feeder creeks and supply wild progeny to the population.

All of which helps explain why CDFW Environmental Scientist Jim Erdman has been out conducting creel surveys at Crowley every opening day since joining CDFW in 2005. Based in Bishop, Erdman’s goal is to contact at least 300 anglers and see which hatchery fish are turning up in their catch, in what numbers, in what proportion of species, and in what condition. The report is an annual check to see whether CDFW’s management plan for Crowley remains on point or whether adjustments need to be considered. The opening day creel surveys have been taking place since 1997 when CDFW biologist Curtis Milliron wrote the Crowley Lake Management Plan.

CDFW volunteer Carl Ronk assisted Erdman this past opener April 27. The two split up at times – one checking anglers along the shoreline, the other awaiting returning boats to the Crowley Lake Fish Camp marina, the only formal boat launch at the lake.

Their tools for the day included a clipboard for note-taking and a 15-inch wooden “Crowley Stick” for measuring fish. CDFW biologists have determined that a fingerling trout stocked in the fall should be 15 inches or greater by opening day in the nutrient-rich waters. Erdman typically completes and submits his report by the afternoon of the opener and shares it with anyone interested. Local papers have been known to reprint it in its entirety.

For the 2019 Crowley opener, the creel survey found shoreline angler success was greatly improved from the previous year with an average catch per angler of 3.66 trout compared to last year’s average of just 0.71 trout. Overall, however, catch rates and total catch per angler were lower than 2018. Fish size was also down. Approximately 41.4 percent of the rainbow trout measured were greater than 15 inches, well below the annual average of around 70 percent. The catch rate fell below CDFW’s management goal of one fish per angler for each hour of effort.

A long, cold winter and late ice-out were cited as factors in a slower-than usual Crowley opener and smaller fish with less time to fatten up post ice-out.

“Crowley Lake did not ice-out until April 10, 2019, and this kept fish in deeper water than usual,” Erdman wrote. “No fish were seen in the McGee, Crooked or Whiskey Creek inlets and few to no fish were seen staging for a spawning run. Water temperatures in the inlets remained below 40 degrees.”

Rainbow trout made up the majority of the catch followed by brown trout. Lahontan cutthroats were scarce. CDFW annually stocks 100,000 Lahontan cutthroat fingerlings in the fall. Cutthroats represented just 0.9 percent of the shoreline catch and 1.6 percent of the boating catch compared to 2018 findings of 11.3 percent of the shoreline catch and 2.2 percent of the boating catch.

Opening day on Crowley Lake, with its big crowds and festive atmosphere, has always been about more than bag limits as reflected in Erdman’s creel survey report.

“Returning boat anglers were a bit slower than usual coming in off the lake probably due to the pleasant conditions on the lake. Relaxing in the sun and drifting in the slight breeze. A grand day to be on the water.”

CDFW Photos. Top Photo: CDFW's creel surveys play an important role in evaluating the lake's management and stocking allocations.

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

 

Categories: Wildlife Research
  • April 29, 2019

One large spiny lobster and four smaller lobsters lined up on green mat on side of boat.

Scuba diver next to rocks and kelp underwater holding up spiny lobster and calipers.

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 link opens in new windowCalifornia Spiny Lobster brochure (PDF).

CDFW Photos.

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

Categories: General
  • April 12, 2019

Laminated sign with fish that reads attention anglers attached to old wooden sign on metal post in grassy area with lake and mountains in background
Lake-side signage lets anglers know Kirman has recently been stocked with wild brook trout and asks for help from anglers in competing a brief survey about their fishing experience.

Seven people in waders and machine backpacks holding nets and yellow poles in stream.
CDFW fisheries biologists electrofish Silver Creek in Mono County to remove non-native brook trout to reduce competition with native cutthroats.

Hand palm facing up with several water bugs in palm
The tremendous amount of aquatic life within Kirman Lake provides a nearly unlimited food supply for transplanted brook trout from Silver Creek and transplanted Lahontan cutthroat trout from Heenan Lake. Kirman itself has no spawning habitat and is dependent on trout plants from CDFW to maintain the trophy trout fishery.

Small speckled fish laid on top of measuring tape and wooden board.
Before release into their new home in Kirman Lake this fall, brook trout were measured and their adipose fins clipped. CDFW scientists plan to track their growth rates with the help of voluntary angler surveys.

It’s a question that has been asked by more than a few eastern Sierra trout anglers: What happened to the fishing at Kirman Lake?

Kirman, a small backcountry lake north of Bridgeport in Mono County, has long been heralded as one of the very few places in the state where anglers could catch trophy brook trout.

While many high-elevation waters hold overpopulations of stunted brook trout measured in inches, the brook trout in Kirman were measured in pounds. Fish in the 2- to 4-pound class were common with numerous reports of brookies exceeding 5 pounds.

The lake requires a moderate, 3-mile hike to reach – just enough distance and difficulty to discourage casual anglers and help minimize some of the fishing pressure, particularly with so many great trout fishing options nearby. The lake is a special-regulations water with limited harvest. It is open to fishing during the state’s traditional trout season from the last Saturday in April to Nov. 15. Only artificial lures with barbless hooks may be used. Only two trout can be kept – with a minimum size limit of 16 inches.

Kirman was a destination known well beyond the confines of Mono County.

Fly fishing author and instructor Denny Rickards included Kirman in his book “Fly Fishing the West’s Best Trophy Lakes.”

Rickards writes, “Those who have made the trek and landed one of these beautiful trout know what a delicate lake it is. Part of the promise here is more than just big brook trout – the lake also harbors big cutthroat. However, the cuts aren’t the primary focus of those who fish here. It’s those big, beautiful brookies that bring fishermen up the trail.”

Author Bill Sunderland likewise highlighted Kirman in his book “Fly Fishing California Stillwaters.” He writes, “The fish here, both brook trout and Lahontan cutthroats from Heenan Lake, grow exceptionally fast. A four-year-old brookie can be twenty inches long and weigh four pounds. Many of them are football-shaped, the result of their rapid growth.”

In recent years, however, the brook trout seemingly disappeared with anglers reporting fewer catches with no brookies in the mix. Fishing reports from Kirman dried up as well at local tackle shops with fewer anglers apparently making the trek.

What happened to Kirman Lake and its trophy brook trout is no mystery to CDFW fisheries biologists, who are committed to restoring the lake to its former glory.

“There’s no spawning habitat,” explained Jeff Weaver, a senior environmental scientist with CDFW who oversees the department’s Heritage and Wild Trout Program. “All the fish in Kirman Lake have been stocked to provide the recreational fishery.”

Brook trout were planted annually by CDFW until 2015 when hatchery problems prevented the raising and delivering of the fish.

What Kirman lacks in spawning habitat it makes up for in food abundance. Unlike many high-mountain lakes where trout eke out an existence in near-sterile conditions, Kirman is the equivalent of a 24-hour, all-you-can-eat buffet. The lake is loaded with all manner of aquatic invertebrates -- water boatman, dragonflies, mayflies and midges – along with high-protein leeches and shrimp-like scuds. The heavy population of scuds accounts for the tremendous growth rate and size of Kirman brook trout.

When Russell Black, CDFW’s new fisheries supervisor for the Inland Deserts Region, learned about the lack of hatchery plants and the poor state of the once-great fishery, he came up with a simple yet creative solution.

This past fall, work was underway at nearby Silver Creek to prepare the water for the eventual restoration of native Lahontan cutthroat trout. CDFW biologists electrofished Silver Creek to remove the non-native brook trout there to minimize competition with the native cutthroats.

Black’s idea: Take those brook trout and transport them to Kirman.

More than 1,300 Silver Creek brook trout in a variety of sizes were relocated to Kirman. Prior to release, the fish were measured and their adipose fins clipped. CDFW biologists encourage anglers at Kirman this upcoming trout season to record their catch and fishing experiences at angler survey boxes lakeside so they can track the transplanted Silver Creek brook trout.

Given the exceptional growth rate at Kirman, CDFW biologists expect anglers to get into some quality fish by the fall.

Even as CDFW shifts its statewide trout hatchery focus to raising and stocking native trout as opposed to non-native brown trout, brook trout or even domesticated strains of hatchery rainbow trout, biologists see a future for trophy brook trout in Kirman and are exploring options to resume annual hatchery stocking.

“Kirman Lake is one of those celebrated fisheries where we weigh management in favor of continuing that recreational fishery,” said CDFW’s Weaver, who himself has fished Kirman a dozen or so times over the past 20 years. “Kirman Lake is managed as a trophy trout fishery and we intend to continue to manage it as a trophy trout fishery. We’ve just been on pause as a result of the lack of stocking.”

The pause may be over, though, as CDFW intends to maintain the supplemental stocking from Silver Creek until regular hatchery plants can resume.

CDFW Photos. Top Photo: This small brook trout was one of many relocated this fall from Silver Creek to Kirman Lake, where it could potentially grow into a trophy-sized fish awaiting anglers this trout season.

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

Categories: Wildlife Research
  • January 18, 2019

Four men and large fishing nets on small fishing boat on water. Marina and levy in background.
Joe Millosovich, an environmental scientist who specializes in lake and fisheries management in the Central Valley, came all the way from Fresno to captain one of the electrofishing boats collecting bass in the Delta Jan. 16. Several of CDFW’s biologists participating in the outing called it one of their favorite days of the year.

Man wearing gray camo foul weather gear, backward ball cap, and black life vest with yellow reflectors behind helm on fishing boat on water. Cloudy skies and grass-covered levy in background
Max Fish, an environmental scientist with CDFW’s Inland Fisheries Program, captained the electrofishing boat that collected the largest largemouth bass of the morning – a 10-pound-plus whopper.

Man wearing blue foul weather gear, blue ball cap, on docked fishing boat holding up two large fish. Water, land, and trees in background.
Kyle Murphy, a senior environmental scientist with CDFW’s Inland Fisheries Program, shows off two of the larger Delta largemouth bass headed for the International Sportsmen’s Exposition demonstration tank in Sacramento.

Among the more popular attractions at the Sacramento International Sportsmen’s Expo each January is the Western Bass Aquarium Demo Tank. The 6,000-gallon aquarium displays dozens of trophy largemouth bass collected by CDFW biologists from the Sacramento-San Joaquin Delta. The aquarium demo tank, with bleachers on both sides, is where professional bass anglers lead seminars demonstrating the latest techniques and can’t-miss lures – all without hooks attached so as not to injure the fish.

“This is the best display of largemouth bass anywhere in the country,” said Kent Brown, the longtime host of the ISE demonstration tank. “And that’s not just me talking. That’s from tournament bass fishermen who travel all over the country. There’s just no bass anywhere that can rival these Delta bass.”

The tank is also a tremendous source of pride for the CDFW fisheries biologists tasked with collecting the fish.

“It’s great for people to see the kind of fish they can catch here in their own backyard,” says Ben Ewing, a CDFW district fisheries biologist who headed the ISE collection effort this year. “All the fish get released back into the Delta immediately after the show and literally are available for anyone with a fishing license to catch.”

A mix of 16 fisheries biologists and volunteers assembled along the Delta near Stockton the morning of Jan. 16, the day before the opening of the four-day ISE show at Sacramento’s Cal Expo. They climbed onto four electrofishing boats to probe likely largemouth hideouts – tule stands, rip-rap shoreline, sunken boats, submerged tree limbs and other structure.

“We all come together to try and make a good display for the public,” Ewing said.

Over the years, a friendly competition has developed. A trophy and bragging rights go to the CDFW boat captain who collects the largest bass for the show. Each of the four captains took off with their crews in different directions searching for a largemouth bass that might not only win the day but one that might top their all-time ISE show record fish of more than 13 pounds.

The boats sent targeted currents of electricity through the water while crew members standing on the bow were ready with nets to scoop up the stunned fish for deposit into the live wells for safekeeping. In more than 20 years of providing Delta largemouth bass for the Sacramento ISE show, CDFW biologists have refined their methods and strategies.

In addition to looking for the largest fish, a mix of sizes is collected. Smaller bass add perspective in the tank and make the biggest fish look even bigger. Suckers, catfish and large sunfish add some fun diversity to the display. Striped bass are a no-go – they don’t do so well in transport and they’ve been known to jump out of the aquarium.

Max Fish, an environmental scientist with CDFW’s Inland Fisheries Program, piloted one of the electrofishing boats. He explained how these vessels are important research tools that allows CDFW scientists to survey fish populations and assess health in the state’s lakes and reservoirs. CDFW puts one of the boats on display at the ISE show each year and points out the connection between the boat and the bass in the tank.

On that overcast January morning with major winter storms looming in the forecast, Fish sent 340 volts of electric current through the shallow Delta waters. The conditions for electrofishing were nearly ideal – the plentiful organic material in the Delta helps conduct electricity while the overcast skies were unlikely to spook fish and send them deep beyond the boat’s effective reach.

Fish said the boat’s electric current ranges about 10 feet deep and about 20 feet wide – roughly the span between the two sets of anodes extending from the boat’s bow into the water.

Fish’s efforts were rewarded with the largest bass of the day – a 10.3-pound lunker among others in the 9- and 8-pound class. After congratulations, photos and good-natured ribbing from his colleagues back at the dock, the 60 or so fish collected by all the boats were shuttled directly to Sacramento’s ISE show in an aerated live well.

Meeting them there was CDFW veterinarian and fish pathologist Keven Kwak, who tested and treated the aquarium’s water to make sure it was safe for what would be the fish’s short, but celebrated stay in Sacramento.

CDFW Photos. Top Photo: CDFW biologists stand ready with nets in hand to scoop up temporarily stunned fish for the ISE’s bass fishing demonstration tank in Sacramento. Biologists look for the biggest and best specimens to showcase the Delta fishery. While the biologists are targeting largemouth bass primarily, the electric current brings up carp, catfish, suckers, striped bass and all manner of sunfish. Within a minute or two, the stunned fish come to and swim off.

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

Categories: General
  • November 21, 2017

Three men brush a white epoxy on a 600-foot-long by 5-foot wide concrete channel
Working late, Mojave River hatchery staff apply FDA-certified epoxy coating to hatchery rearing ponds.

a tank truck parked next to a concrete fish hatchery raceway with palm trees in background
CDFW fish transportation truck at Fillmore Hatchery

An African American man in a California Fish and Wildlife uniform squats to read something on a low concrete wall at a fish hatchery
Acting Mojave River Hatchery Manager Forest Williams at work

Seven people watch fish come out of a 10-foot pipe from a CDFW tank truck, into a root beer-colored river
A hatchery crew releases trout into the Feather River

view from river-level of water and fish pouring from a tank truck, through a pipe
A fishy view of trout planting on the Feather River

The beginning of trout fishing season in Southern California is just around the corner, and CDFW biologists and hatchery staff are striving to maximize hatchery trout availability for the many anglers who will cast lines in coming weeks. Trout angling in lower-elevation waters of Southern California generally begins in November and continues through April, to correspond with colder water temperatures that can sustain stocked trout.

Precise temperatures are just one of the criteria that must be met before trout stocking begins. Currently, these conditions are approaching optimal levels, but CDFW is running about two weeks behind schedule due to unforeseen circumstances at Mojave River and Fillmore trout hatcheries, two of CDFW’s southernmost facilities.

The Mojave River Hatchery, built in 1947, raises and stocks a ten-year average of 340,000 pounds of catchable trout per year. Beginning in June of this year, extensive maintenance and facility upgrades necessitated turning off the water for a six-month period. While the completed upgrades will ultimately result in better and more efficient trout production for Southern California, the project ran about two months behind schedule. Water is scheduled to flow again at Mojave River Hatchery in late November and the hatchery will be populated with fingerling trout for fast growth. Mojave’s year-round water temperatures yield fast trout growth resulting in maximized yield in minimal time.

While the Mojave River Hatchery was closed, Fillmore Hatchery, built in 1941 on the Santa Clara River, experienced a significant loss of trout inventory intended for Southern California angling due to gas bubble disease. Gas bubble disease is a result of supersaturated gasses (oxygen, nitrogen and carbon dioxide) present in well water pumped from a deep aquifer. While Fillmore Hatchery is equipped to aerate this water and make it suitable for trout, an unknown variable (possibly a drought-depleted and then recharged aquifer) overwhelmed that ability. In an average year, Fillmore Hatchery produces about 400,000 trout for lakes and streams in Southern California. To reduce fish losses from gas bubble disease in the last several weeks, catchable fish were stocked from Fillmore to appropriate waters, and some fish were transferred to other hatcheries. Ultimately, the gas bubble disease at Fillmore resulted in a loss of about 50 percent of inventory. While emergency measures taken by Fillmore staff and

CDFW fish pathologists resulted in better conditions and lower gas super-saturation, the hatchery must be depopulated so that the issue can be addressed entirely. As soon as all trout are removed, hatchery staff and scientists will increase the gas diffusion capability of aeration towers at Fillmore, in order to handle supersaturated well water for the short and long term.

The status of these two hatcheries presented a substantial problem for trout stocking in Southern California that was solved in part by hatcheries in Central and Northern California. These hatcheries have sufficient catchable size trout to supply Southern California’s approved waters immediately and in coming weeks. Thanks to strategic planning and trout production at a statewide level, Northern and Central California can supply fish to Southern California without impacting originally scheduled trout releases in their respective areas.

Trout stocking for Southern California waters will begin this week and hatchery trucks are on the move. Hatchery staff will work quickly to distribute trout to as many approved waters as possible. Trout stocking to Southern California will initially be lighter than usual, but will likely pick back up in 2018. As Mojave River Hatchery comes back online, fish transferred to that facility will be fed and reared to maximize daily growth. We anticipate another large batch of catchable trout available for Southern California toward early spring 2018.

Hatchery staff will be doing everything possible, statewide, to maximize trout production and releases to approved waters in the coming months. Staff work diligently for the angling public and appreciate their continued support.

The statewide planting schedule is updated in real time online.

CDFW photos. Top: Steelhead trout at Mokelumne River Hatchery

Categories: General