OLIN FEUERBACHER COULDN’T believe his eyes. It was December of 2017, and he’d been reviewing film captured the night prior, from a captive population of Devils Hole pupfish—the rarest fish on the planet.
These inch-long, electric blue fish have been stranded in a submerged limestone cavern in the Nevadan desert since the last Ice Age. The fish only live upwards of a year, and as such the population is prone to large swings, but lately it’s looked grim: In 2013, the entire population dropped to just 35 fish.
In the years since, the U.S. Fish and Wildlife Service opened the Ash Meadows Fish Conservation Facility, which houses a gigantic, 100,000 gallon replica of Devil’s Hole that can be controlled and protected. The goal was to create a “lifeboat population” of pupfish that could supplement or replace the ones in the wild if they should ever go extinct.
As Feuerbacher watched the infrared footage, which can visualize objects in the dark, a tiny pupfish larva smaller than a peppercorn flitted into the camera’s frame. This was big news. When a population gets as low as that of the pupfish, every animal—wild or captive, larva or adult—is critical to the species’ survival.
“I was pretty excited to see there was reproduction going on in the tank, and I just watched it for a little bit,” says Feuerbacher, a fish biologist with the U.S. Fish and Wildlife Service. “Then I saw a beetle swim past.”
It began circling the fish, and closing in.TODAY’SPOPULAR STORIES
“Then it just dove in and basically tore the fish in half right while I was watching,” says Feuerbacher.
From horror to hope
Scientists have known for a few decades that diving beetles share the waterlogged limestone cavern known as Devil’s Hole with the pupfish. With over 4,300 species known to science from every continent except Antarctica, there aren’t many inland bodies of water diving beetles haven’t colonized. In fact, Feuerbacher says that when he and other scientists descend into the hole to do pupfish counts, they can often feel the aquatic insects biting at their legs.
And when they built the Ash Meadows facility, the scientists tried to create a mirror image of Devil’s Hole, which meant bringing in water, substrate, and algae from the natural environment. So the fact that some diving beetles had hitchhiked along didn’t seem like a bad thing at first.