HATCHERY

generations of hatchery-born offspring. A third generation is expected later this year. LIFE IN CAPTIVITY

Because these fish are “left over from an experiment,” they will probably never be released into the wild, said Mike Schwemm, senior fish biologist for the U.S. Fish and Wildlife Service in Las Vegas. But the captive population does provide a valuable resource for studying the dace’s behaviors, environmental tolerances and mating habits, Schwemm said.

The hatchery fish also can be used to develop a complete genetic profile — or genome — for the species.

The Moapa dace has been under federal protection for almost 50 years. It’s entire habitat is confined to the 116-acre Moapa Valley National Wildlife Refuge, some adjacent private land and the Warm Springs Natural Area, a 1,218-acre tract the Southern Nevada Water Authority bought for $69 million in 2007.

According to the latest count, conducted last month, there are approximately 1,165 Moapa dace left in the warm, spring-fed streams 60 miles northeast of Las Vegas that it calls home. That’s the lowest February total in five years.

A year ago, the population stood at 1,859.

Schwemm said it’s “hard to put too much stock in any one count,” but the latest results have him thinking about conducting “an intermediate count” between now and the next regular population survey in August. Contact Henry Brean at hbrean@reviewjournal.com. Follow @refriedbrean on Twitter.