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 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