LAS VEGAS (AP) - One of the world’s most endangered species took a small step away from oblivion over the past year, as the wild population of Devil’s Hole pupfish nearly tripled from 35 in April 2013 to 92.
Researchers are also reporting progress in a captive-breeding program to provide a backup population for the isolated and unique natural desert ecosystem near Death Valley.
“We’re actually seeing quite a bit of spawning activity,” aquaculturalist Olin Feuerbacher told the Las Vegas Review-Journal (https://bit.ly/1svET5V).
An annual spring census of the dime-sized fish, conducted last month, tallied fish in the one water-filled cavern in Nye County where they live about 90 miles west of Las Vegas.
In September, there were 65 - almost twice the 35 fish that in April 2013 represented the lowest total since regular counting began more than 40 years ago.
The fish has been under federal protection since 1967, but officials say extinction remains a very real possibility.
Experts can’t explain the population growth with any certainty, but say that man-made improvements to the pupfish diet and habitat could have something to do with it.
The fish now receive supplementary feedings five days a week, and have new places to hide thanks to the addition of artificial “plants” made from sterilized shag carpet and clumps of yarn. The additions provide cover for young fish and eggs that might otherwise be eaten by adults.
Meanwhile, less than a mile away from Devil’s Hole, researchers at a new $4.5 million Ash Meadows Fish Conservation Facility are trying to establish a viable, captive-bred population for the first time.
Using just a few dozen eggs painstakingly collected from Devil’s Hole, Feuerbacher and his team have successfully hatched and raised 29 pupfish to adulthood. They hope soon to begin hatching a second generation of captive-raised fish from their original crop of eight females and 12 males, now about 6 months old.
The population of Devil’s Hole pupfish peaked at 544 in the fall of 1990, but began to decline in 1996 for reasons researchers still can’t explain.
Today, the species is closely studied and monitored by researchers from the National Park Service, U.S. Fish & Wildlife Service and Nevada Department of Wildlife.
Devil’s Hole is guarded by chain-linked fence, barbed wire and a sophisticated security system that provides 24-hour video surveillance.
The spring-fed cavern is widely considered the world’s smallest habitat for a vertebrate species. Water in the hole is thermally heated to about 93 degrees and carries barely enough dissolved oxygen to support life.
At the surface, the pool is about 8 feet wide and 60 feet long, but the cavern angles down into the groundwater table to an undetermined depth. Divers have been as deep as 435 feet without finding the bottom.
Pupfish are known to go as far down as 100 feet, but they spend most of their time on the shelf near the surface, which brings another strange phenomenon into play: Distant earthquakes, some as much as 1,700 miles away, occasionally cause water in the pool to slosh back and forth. That dislodges algae and disrupts the pupfish’s natural food supply.
Later this month, the team at the research facility plans to begin moving the first pupfish into a replica of Devil’s Hole, built inside a semi-open structure designed to provide the same seasonal variations in sunlight and weather.
The goal is to establish a self-sustaining pupfish population in a 100,000-gallon tank filled with water pumped from the same aquifer that fills Devil’s Hole.
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Information from: Las Vegas Review-Journal, https://www.lvrj.com
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