Saving one of the world's rarest fish

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Saving one of the world's rarest fish

August 16, 2018 - 09:38

Our Koi can survive lots of different water parameters, but these fish are even more amazing!  You will enjoy reading the story about their rare habitat.

We're driving through one of the harshest climates in the world, where the summer heat regularly reaches three digits. The barren landscape shows little sign of life and though it's not even noon, the temperature is close to 90 degrees.

CNET video producer Chris Monroe and I anticipated the extreme heat and packed tons of water. I'm also wearing overpriced SPF-rated clothing over the coats of sunscreen I've slathered on. It's the Mojave Desert, after all.

But as arid as the land is, there's life here if you look for it. Kevin Wilson, a National Park Service aquatic ecologist, swerves sharply at one point to avoid a sidewinder on the road. We're following him in our dirt-coated rental car to a place where life is even more abundant: the mouth of an underwater cave called Devils Hole in southern Nevada, outside Death Valley National Park. (It's "Devils" because the US Board on Geographic Names has a policy against using apostrophes.)

In addition to rattlesnakes and a thriving killer bee population — "Are either of you allergic to bees?" Wilson asks — Devils Hole is home to an endemic and endangered species of fish called the Devils Hole pupfish: a tiny silvery-blue fish, just 1 to 3 inches long, that got its name because of the way they frolic like puppies. 

It's been called one of the rarest fish in the world.  Man-made changes to their fragile environment have lowered the adult population in Devils Hole to fewer than 100. Divers counted only 35 adult pupfish in spring 2013, an all-time low according to the US Fish and Wildlife Service.

Wilson — along with other scientists and support staff from the NPS, the USFWS and the Nevada Department of Wildlife — is working to save the pupfish from extinction. Why? Scientists believe these tiny swimmers can teach them about how species survive in seemingly unforgiving conditions.

Their survival depends on technology, including sensors, lasers and solar energy.      

Devils Hole is located in the Ash Meadows National Wildlife Refuge, the largest oasis in the Mojave, about 90 miles northwest of Las Vegas in the Amargosa Valley. (Though administered by Death Valley National Park, Devils Hole is outside the park's official boundaries.)

It doesn't look like much from a distance, but the steep walk down a rocky path leads to a spectacular sight as you approach the mouth of the cave: You're suddenly surrounded by walls of limestone.

Algae covers the surface of Devils Hole, giving it a murky look, but Wilson describes it as "gin-clear" when you're in the water. Divers 80 feet deep can see people standing near the water's edge. The true depth of Devils Hole is unknown, though divers have descended as far as 436 feet without seeing the bottom. It's likely more than 500 feet deep. The tiny fish spends most of its life in the top 80 feet -- one of the smallest habitats known for any vertebrate. 

At least 26 plants and animals that aren't found anywhere else in the world, the pupfish included, live in this 24,000-acre protected area. That makes it the second-highest concentration of endemic species in North America. Olin Feuerbacher, a USFWS fish biologist at the Ash Meadows Fish Conservation Facility, describes Devils Hole as the worst environment you can think of for a fish. 

"The water is constantly 93 degrees Fahrenheit, dissolved oxygen is at lethally low levels and within this area it's also the highest-elevation spring," Feuerbacher says. "So anything that happens to Devils Hole will probably, as water levels drop or as temperatures change, become evident in other stream systems."

Devils Hole is open to visitors, but the overlook is enclosed by a metal cage that prevents you from going down to the water. "We call this our visitors tunnel or public prison," Wilson says with a laugh. 

There's a reason for these precautions. People regularly threw things in the water before the enclosure was built, killing many of the already endangered pupfish. 

The decline in the pupfish population began when people started farming in the Amargosa Valley in the mid-to-late 1960s. One rancher installed a well near the Devils Hole boundary line and began pumping groundwater -- causing the water level in Devils Hole to drop and revealing the pupfish habitat on an underwater shelf near the surface.

Before then, the fish historically numbered over 450 in the fall and 250 in the spring. (The seasonal variation is natural.) It was listed as an endangered species under the 1966 Endangered Species Preservation Act and later added to the Endangered Species Act of 1973.

In 1970, the ranch owner petitioned the state of Nevada to pump water from more wells near Devils Hole, but the National Park Service protested. The case ended up in the Supreme Court, which in 1976 upheld a lower court ruling against the rancher.

At last count earlier this year, there are 87 Devils Hole pupfish, primarily living on their shelf habitat. "We knew there was a relationship between the shallow shelf and water level," Wilson says. "And that's because it has the best habitat for spawning and egg-hatching success, and also for food availability."

Because water level is so closely tied to the fish's survival, Wilson and his team monitor it 24/7. They also regularly measure temperature, pH, oxygen and conductivity using a variety of sensors and data loggers. Fittingly for such a sun-baked place, all of the equipment is solar-powered.

There's so much to do that Wilson says the resident team doesn't work alone. "We bring in specialists from academia," he says. "We also [bring in] other federal and state agencies to apply certain technologies to specific research or hypotheses that we are interested in."

One visiting scientist, Mark Hausner, used fiber-optic cables to send lasers into Devils Hole to precisely measure water temperature down to a depth of 200 feet in a variety of weather conditions. Teams of divers also go into the 93-degree water to keep an updated count of the pupfish.

Wilson's ultimate dream? Tech to monitor individual fish and see where they go in a 24-hour period. That's tricky, though, Wilson explains, because the tiny fish are "sensitive to handling."

One of the most fascinating areas of research isn't at Devils Hole at all. Feuerbacher works in a facility about a mile away where he and other staff maintain a 110,000-gallon re-creation of the habitat. About 100 Devils Hole pupfish currently live there.

The purpose of the facility is to create a lifeboat population. If something catastrophic were to happen to Devils Hole, the habitat fish could potentially repopulate it. "At the same time, we're trying to develop this as a living laboratory too," Feuerbacher says. "That way we'll get some insight into why the Devils Hole pupfish are challenged in the wild."

Essentially, it's the team's backup plan.

Walking through this satellite Devils Hole was otherworldly. It's a giant man-made pool, but the water has nearly the same temperature and low oxygen levels as Devils Hole.

Computers keep everything running, but the team makes unexpected late-night trips to the Ash Meadows Fish Conservation Facility when problems arise. They get alerts or calls, texts and emails when something isn't working, depending on the potential severity of the issue.

Feuerbacher remembers a time when the team had its first 29 fish in aquariums and the computer system texted him at 1 a.m., saying there was water on the floor. "We didn't know, did a filter have a little leak or did all of our tanks explode?" he says. "So that one involved a pot of coffee and a quick drive out here."

Now they have security cameras set up so they can look around and listen to the equipment without having to make a trip out to Ash Meadows, which is about an hour away from where most of the staff live.

Wilson, Feuerbacher and the rest of the people working to save the endangered fish have made progress. Pupfish numbers are increasing. In just the last five years, the Devils Hole population rose from 35 to 87 fish; Ash Meadows went from 29 fish to 100.

There's no specific population target they're trying to hit. They're just focused on keeping their off-site population going strong. If that continues to go well, Feuerbacher says they'd like to introduce them to public aquariums and research facilities.

"It may just be that they're cute fish," he says. "But we also don't know what discoveries might come from these fish. If you let them go extinct, we'll never know."

Feuerbacher and Wilson say they feel a sense of personal responsibility for saving the pupfish. After all, the water level started dropping only when humans began pumping groundwater.

"If it's a natural evolutionary pathway for the species, that's fine. Species do go extinct and new species evolve," Wilson says. "But since we've had a human impact on this ecosystem and the fish, I think that -- as a society -- we need to decide what is important. 

"I think it's important. Do you?"

This story appears in the fall 2018 issue of CNET Magazine.  

https://www.cnet.com/features/the-deep-dark-quest-to-save-the-pupfish/?f...


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