In a glimmer of hope for one of the world’s rarest fish, scientists have counted 191 Devils Hole pupfish this spring in their tiny desert habitat. This number marks the highest spring count for the critically endangered species in more than two decades. The Devils Hole pupfish (Cyprinodon diabolis) is found only in the upper reaches of a single deep limestone cave in the Mojave Desert in the western U.S. state of Nevada. The entire species lives on a shallow rock shelf measuring 3.3 by 4.8 meters (11 by 16 feet), making this the smallest known range of any vertebrate species on the planet. Twice a year, biologists from the National Park Service, U.S. Fish and Wildlife Service, and Nevada Department of Wildlife peer from scaffolding above the pond and then enter the water with scuba gear to count pupfish in Devils Hole. They methodically comb the entire habitat, from the sunny shallows to depths of more than 30 m (100 ft), looking for the iridescent blue desert dwellers. “It was really encouraging to see such a large number of young fish during these spring dives,” said Brandon Senger, supervising fisheries biologist for the Nevada Department of Wildlife, who has been conducting scuba counts at Devils Hole since 2014. “Conditions within Devils Hole looked healthy, so we have hopes of high recruitment over the coming months that will lead to a large population in the fall.” Nearly the entire natural range of the species is visible in this photo. The…This article was originally published on Mongabay
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