Fish experts not worried about recent drop in endangered Moapa dace population

A count conducted last week at the headwaters of the Muddy River, about 60 miles northeast of Las Vegas, placed the population of Moapa dace at 1,635. That's a decline of about 25 percent from a year ago, but biologists aren't concerned about the status of the endangered fish. (Las Vegas Review-Journal file photo)

The population of an endangered fish found only in northern Clark County declined by 25 percent over the past year, but biologists insist things are still looking up for the Moapa dace.

For two days last week, about a dozen people fanned out to count fish in the warm springs and streams that form the headwaters of the Muddy River. The team logged 1,635 Moapa dace, the lowest August total counted since 2012.

Last August, the population stood at 2,182.

But fish biologist James Harter isn’t worried, in part because the Moapa dace is still in much better shape than it was just eight years ago.

Protectors of the endangered fish used to perform just one count a year each February, but in 2008 they added the second count in August after the population suddenly plunged from almost to 1,200 dace to less than 500 in one year.

The numbers have gradually come back up since then, thanks to extensive predator-control and habitat-restoration work in the spring-fed oasis 60 miles northeast of Las Vegas that the dace calls home.

Biologists might be more anxious about this year’s numbers if the decline coincided with some obvious threat to the fish — for example, fresh habitat damage, a drop in stream flow or the reintroduction of predatory fish.

“We saw a decent amount of reproduction, and the habitat looks good. Overall I think they’re pretty good numbers,” said Harter, who works for the U.S. Fish and Wildlife Service in Nevada. “A little dip like this is not reason for concern.”

Counting the dace is no easy task. Harter said he and his crew had to put on wet suits in the triple-digit heat and crawl along the bottom of shallow, narrow streams searching for fish amid rocks, logs and other debris.

“It’s a workout,” he said.

The finger-length fish with a black spot on its tail has been under federal protection for almost 50 years. The dace’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.

The wholesale water supplier for the Las Vegas Valley joined the effort to protect the Moapa dace under a 2006 federal agreement that cleared the authority to pump groundwater at nearby Coyote Springs.

Contact Henry Brean at hbrean@reviewjournal.com or 702-383-0350. Follow @RefriedBrean on Twitter.