More pupfish swimming in Devil's Hole

The tiny Devil's Hole pupfish, found only in a small, deep pool in the Nevada desert, has been teetering on the brink of extinction for years. In the spring of 2006 there were only 38 of them, down from roughly 500 in the mid-1990s.

The reasons for the decline are unclear. But government scientists trying to reverse the trend now appear to be enjoying a bit of success. The autumn count of the iridescent blue fish has risen for three years in a row to 126 this fall, the first steady increase in more than a decade.

Convinced that the pupfish problems are tied to a shortage of nutrients, biologists took the highly unusual step of feeding the fish. "It was not done lightly," said Bob Williams, Nevada field supervisor for the U.S. Fish and Wildlife Service. "When you start to artificially augment a wild population, it is a sign the species is really in trouble."

The high-nutrient fish food, made at a federal research lab in Montana, is based on a mix given to Rio Grande silvery minnows in a New Mexico hatchery. The Devil's Hole feeding started last fall and continued over the winter and into spring to try to maintain an adult spawning population.

Winter is the most difficult time for the pupfish and Williams said supplemental feeding will probably again be considered in the coming months.

The Devil's Hole is a detached piece of nearby Death Valley National Park, just over the California border. The water filled-cavern is more than 500 feet deep, dangerous enough that years ago, two scuba divers drowned exploring its depths.

The pupfish are an isolated colony that has survived in the hole for at least 10,000 years, a remnant of wetter times in the desert. They have been found as deep as 66 feet, but forage and spawn on a rock shelf near the surface of the pool.

Devil's Hole was the subject of a landmark ruling by the U.S. Supreme Court in 1976, when justices recognized its water rights and restricted nearby agricultural pumping that was lowering pool levels to lethal levels.

-- Bettina Boxall

Photo: David Ek of the National Park Service points to a pupfish in Devil's Hole. Credit: Stephen Osman / Los Angeles Times