Endangered Devils Hole pupfish slowly increasing in numbers

A curious captive-raised Devils Hole pupfish at the Ash Meadows Fish Conservation Facility. In April, scientists counted 175 pupfish in their Nevada home, the most of this critically endangered species observed in a spring count in 22 years. (OLIN FEUERBACHER/USFWS)

SAVING AN ENDANGERED FISH IN THE DESERT

By John Heil

For more than 50 years, the U.S. Fish and Wildlife Service, National Park Service, Nevada Department of Wildlife and their partners have used scuba and surface monitoring for Devils Hole pupfish, and it appears conservation and recovery efforts are paying off.

This past April, scientists counted 175 pupfish, the most observed of this critically endangered species in a spring count in 22 years. Fall counts are typically higher due to greater food resources as a result of more sunlight throughout the summer months.

Brandon Senger, supervisory fisheries biologist for NDOW, scubacounted the “surprising” number of young fish below the surface with other biologists, noting that the fish appeared to be in “both remarkable condition and very active.”

SMALL FISH, EVEN SMALLER RANGE

Devils Hole pupfish (Cyprinodon diabolis) live in the upper 80 feet of a deep water-filled cavern and sun-lit shallow pool at the cavern’s entrance,

making this the smallest range of any vertebrate species on the planet. Devils Hole is a detached unit of Death Valley National Park surrounded by the Ash Meadows National Wildlife Refuge in Nye County, Nevada.

“Devils Hole is still under the impacts of groundwater pumping in the 1960s, so I feel that we have a duty as a society that if we’ve impacted the habitat for this pupfish, then we should do something to try to save it,” said Kevin Wilson, aquatic ecologist for Death Valley National Park, who manages the resources of Devils Hole.

The importance of the pupfish is more than just biodiversity and the Supreme Court decision in 1976 to protect the species accordingly, per senior USFWS fish biologist Michael Schwemm.

“The protections that this iconic fish has, and the decisions made to support it in light of human development in the region caused an increased awareness in general throughout the desert southwest to protect other species of desert fishes,” Schwemm said of the Supreme Court decision. “This created an awareness of water issues in the desert southwest and an inspiration to do more.

“It’s just such a different species and it is remarkable that it has managed to survive. It lacks pelvic fins due to the extreme conditions such as low food resources and high temperature, adapting to habitat conditions which have evolved over time.”

Kevin Wilson, the National Park Service’s Devils Hole program manager discusses habitat with James Woolsey, superintendent at Great Basin National Park, as divers Brandon Senger of the Nevada Department of Wildlife and Mal Maloney of Volunteer In Park surface in the pupfish cavern’s pool. (OLIN FEUERBACHER/USFWS)

REPLICATING HABITAT

Those conditions have been mirrored in a 100,000-gallon tank at the Ash Meadows Fish Conservation Facility. This captive population, which is currently around 300 fish, guards against extinction, according to fish biologist and facility manager Jennifer Gumm.

Population size in the wild is estimated by counting fish throughout the habitat, with standard counting protocols. Scientists scuba dive to count fish in the cavern, starting at depths below 100 feet. Simultaneously, other scientists count fish on the shallow shelf at the water’s surface. The final count includes both surface and underwater fish.

“It’s not the way that you would think of to count most species of fishes,” said Gumm. “The unique cave habitat of Devils Hole and the population being so small for so long – those different components contribute to this being the best way to get a population size estimate.”

Before the 1990s, the population was around 200 pupfish in the spring. However, pupfish numbers have been especially low during the last two decades, averaging only 90 fish. This spring’s count continues an overall increase seen during the past nine years, from the all-time low of 35 fish in spring 2013.

A return to higher numbers of pupfish this time of year could signal important changes in the ecosystem.“Such shifts highlight the

“It’s just such a different species and it is remarkable that it has managed to survive,” said USFWS fish biologist Michael Schwemm on the Devils Hole pupfish, which are only found in a section of Death Valley National Park just across from the California border in Nevada. (OLIN FEUERBACHER/USFWS)

Jeffrey Goldstein, NPS fish biologist, conducts a stereo video survey of Devils Hole, allowing precise size measurements of the fish encountered during the dive.

importance of maintaining long-term data as we work to find out what’s changed,” said Wilson.

CHANGING UP THE PROCESS

After the second population crash in 2013, with the previous dire situation coming in 2006, Schwemm said something needed to be done.

“In 2017, the managing agencies met to discuss how to react more efficiently next time,” Schwemm said. “We knew this was something we’d need to deal with – be able to respond quickly – so we developed a strategic plan with baseline information in case anyone on the team ever left, so we wouldn’t have to reinvent the wheel and start from ground zero.”

The agencies are now working collaboratively to implement the strategic plan and be proactive in management of the species. The next pupfish count occurs next fall.

“It was exciting to see this shift (both in collaboration and pupfish numbers), because it allows more opportunities to study and explore new management options.”

Other research questions include studying genomic work to understand the genetic variation in both the wild and captive populations. “There is a really high potential that this will transform what we know and how we manage the species,” said Gumm.

Scientists are also looking at the fish in captivity to understand impacts of the environmental variables, including climate change.

“Being able to understand how temperature influences development, growth rates and morphology is something else we are looking at,” said Gumm. “So having success in captive breeding and high fish numbers, both in the wild and in captivity, is allowing us to do a lot more research to understand the species and inform management and recovery.”

Finally, according to Gumm, they have recently started understanding more about the physiology (how the body functions) of the fish by looking at waterborne hormones, where

Biologists count pupfish on the shallow shelf in Devils Hole, while divers simultaneously tally those in the cave system to depths of approximately 110 feet. Pictured front to back: Kevin Wilson, NPS aquatic ecologist, Devils Hole program manager, Death Valley National Park; Jennifer Gumm, USFWS fish biologist/ facility manager at Ash Meadows Fish Conservation Facility; Michael Schwemm , USFWS senior fish biologist, Southern Nevada Fish and Wildlife Office.

(OLIN FEUERBACHER/USFWS)

between agencies and other partners per Gumm, Wilson and Schwemm.

“This isn’t just one agency that is working on the recovery and conservation of this critically endangered fish,” said Wilson. “This interagency effort shows that it’s better to play well together in the sandbox and check your egos at the door. We’re really working well together now as a group. The pupfish and the habitat are the important part and we as scientists and managers are just trying to do what is best for them. It takes a team.”

Gumm agreed. “We are likely seeing some of these positive trends in population size because of the coordinated efforts that we have between the National Park Service, U.S. Fish and Wildlife Service, Nevada Department of Fish and Wildlife, as well as outside partners,” she said.

Thanks to the recent population increases in the wild and captivity, scientists are hopeful as they look towards the next 50 years of Devils Hole pupfish conservation. CS

scientists can get the hormone levels just from the water the fish are in as a tool for understanding reproduction, and stress.

A TEAM EFFORT

All of this has come together as a result of a strong effort at collaboration

"This interagency effort shows that it’s better to play well together in the sandbox and check your egos at the door. We’re really working well together now as a group. The pupfish and the habitat are the important part and we as scientists and managers are just trying to do what is best for them. It takes a team," said Michael Schwemm. Devils Hole dive team and surface support personnel pose after a successful weekend. Pictured left to right: Schwemm and Mike Bower (USFWS), Brandon Senger (NDOW), Ambre Chaudoin (NPS), Peter Garcia (Volunteer in Park), Jeffrey Goldstein and Kevin Wilson (NPS), Mal Malone (VIP), Jenny Gumm (USFWS), and Steve Cane and Robert

Editor’s note: John Heil serves as the deputy assistant regional director for external affairs in the USFWS Pacific Southwest Region headquarters in Sacramento. For more, go to fws.gov/cno.

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In many parts of California, summer means hot temperatures but also lots of opportunities to catch fish. Reading the water and knowing how and where different species will be this time of year will increase your success, as will dressing to stay comfortable while fishing in the heat. (JEFF WALTERS)

STAND THE HEAT, STAY IN THE KITCHEN

TIPS FOR FISHING DURING CALIFORNIA’S SCORCHING SUMMER

By Jeff Walters

Fishing California’s super hot summer days and nights may sound like a great idea – until the outdoor temps reach the mid-90s and higher.

Hopefully, you can jump into the water you’re fishing and cool off. However, if stuck without the chance to take a dip, it can be ridiculously hot while fishing – even more so when the fish just aren’t biting. It’s just what comes with angling the state’s rivers and lakes during these months. But the facts surrounding fishing in hot summer temps may surprise you; after all, the fish are relatively nice and cool in the water. The differences in your approach boil down to the species of fish you’re pursuing and their food source, and water temps, clarity, depth and whether it is moving or standing. So let’s take a look at some of the differences around fishing these hot summer days and nights.

HOW SPECIFIC FISH HANDLE THE HEAT

Working jigs and other lures around docks is a good strategy for summer fishing in the early evening. (JEFF WALTERS)

a difference on these days. Big largemouth bass retreat into cooler, deeper water as the sun gets higher in the sky. Bluegill and other smaller panfish seek shelter in the weeds, rocks and ledges. Catfish must keep moving to stay cool or bury themselves in mud someplace if they can find it. Trout like it cold, so you know they will be in deeper water if not a coldwater environment already.

Understanding the water you’re fishing and how fish relate to it is half the battle; the other half is figuring out the right bait, lure and presentation.

Hot days and nights present a different feeding pattern for most fish, and that also depends on the prey that is available. Largemouth and smallmouth bass are not the baitchasing type of fish that pelagically oriented trout, stripers, white bass and others can be. Largemouth will hide in deeper water when the temps skyrocket. Finding these hiding spots without electronics or if you’re shorebound can be a challenge, which is why knowing how to read the water and surroundings is a great way to increase your odds.

Look for drop-off points where the shoreline is steep. Rockpiles, earthen dam facings, and under docks and moored boats are always good spots for bass to hide away from the heat and strong daytime light.

KNOW YOUR FISHERIES

Understanding the water you are fishing is very important. Consider some of these questions: Have you fished here before? What are water depths in the areas you may know about? Is the water clear, moving, stained or just plain muddy?

Then look at the surroundings. Are there rockpiles and, if so, are they man-made? This makes a difference because, believe it or not, most random rockpiles along the shore that are man-made are put there for various reasons, such as fish habitat. Learn as much as you can about the water you are fishing; it makes a big difference.

CAN I HAVE FRIES WITH THAT?

Since it is summer and the spawn was a few months ago, there will be lots of little fish fry swimming around and in turn attracting larger fish. The best time to use smaller-style jigs and lures is early morning and early evening, when temps are cooler and fry simply stay closer to the open shoreline.

Larger fish will sneak up on the schools for an easy meal. And other fish species, crayfish, turtles and

Author Jeff Walters (right) and his son Jason enjoy the camaraderie (and cooler weather) of night bass

fishing. (JEFF WALTERS)

birds will all want their fair share of these tasty little morsels to dine on. Understanding how these other creatures feed will often affect your fishing success.

Bass will bite just about anything that comes their way and topwater baits have always been a go-to style of lure on these hot summer days. Baits resembling mice, lizards and even large rats offer a big, fat meal for a big, hungry bass. There are so many styles and options of topwater lures to choose from; understanding the water you are fishing plays a big part in that decision-making process.

If there are lily pads and other plant matter close to the top of the water column, then a bouncing frog or swimming lizard will work. If the area you are fishing is void of anything except rocks and boulders, then a mouse pattern or lizard style of lure will do the trick. Again, understanding the water you are fishing is key.

WHEN THE NIGHT COMES

When temps cool down at night, don’t forget to fish the docks. Even as lights come on around the water, bigger fish won’t spook easily. A lot of bigger panfish feed at night, chasing fry and larger insects attracted to dock lights. Try using smaller jigs.

Fly fishing at night – think topwater bugs, poppers, frogs and lizards – works well when targeting lighted docks and boats. Soaking a nightcrawler under a lighted bobber or on the bottom near lighted dock areas can also provide excitement, as you never know what is going to bite.

CAT FIGHTS AFTER DARK

Fishing at night for catfish has always been a favorite of many anglers during the summers. The scorching daytime temps drop; the small campfire helps keep the flying insects away; the radio plays some tunes; and everybody tells stories of times gone by. It makes for a great evening.

Rigging up heavier lines and plunking on the bottom with

Filling a stringer full of catfish caught after dark is a great way to combat the sizzling summer weather. This lucky angler had a good evening at San Diego’s

Poway Lake. (JEFF WALTERS)

tasty offerings like chicken livers, nightcrawlers, shrimp and other cut baits is the way to do it. If you fish with others or have a second-rod validation, you can rig multiple different baits to see what works best and then use that on other lines. Outfitting the rods with bells, lights and/or alarms will tell you when a fish is biting.

If you plan on being out there for a while, throwing a crayfish trap or two closer to shore is also a good idea. This is the time to relax and enjoy some quality fishing.

However, catfish are not the only nighttime prowler. Believe it or not, trout will start sneaking in toward shoreline in the hopes of ambushing some prey. Trout like to move along the bottom rockpile areas looking for big tasty insects and crayfish. These lake-bound trout will travel in patterns the same as they do in the open water, but under the cover of darkness they will be closer to shore.

MOVING TIME

If fishing cool moving water, you have a whole different type of fishing to adapt to. Trout will still bite at night, but the fish will be more selective as they cruise along the shorelines in search of big bugs and tasty little crustaceans.

Where allowed under the regulations, using live bait at night in cold and moving water works well. Some fisheries do not allow the use of live bait. If that is the case, then the old tried-and-true dough baits will suffice, since trout are really sightsensitive after chasing tiny bugs all day. Let their ability to smell your dough bait work instead.

KEEP COOL IN THE HEAT

Just remember that even when summer temperatures rise, so do the fishing opportunities. Understanding the type of water you are fishing is the most important part of becoming a successful angler this time of year.

Tight lines, everyone, and stay cool. CS