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By Mike Donahue
Moapa Valley Progress

Biologists performed a semi-annual snorkel count last week of the Moapa dace, a small fish which exists only in the spring flows at the headwaters of the Muddy River. Photo by Mike Donahue.
A two-day snorkel survey of the Moapa dace, tiny endangered fish that live only in the waters in and around Warm Springs, counted an estimated 654 fish last week. This was only a slight decrease from the August 2011 assessment.
But while the numbers are 59 lower than six months ago, Lee Simons, a biologist with the U.S. Fish and Wildlife Service (USFWS), said the slight drop isn’t especially important since there are typically fewer fish in the winter.
“It’s more significant that the numbers are up 80 fish over the 574 counted in February 2011,” he explained. “These are pretty good numbers for us. This actually shows the population is improving and that’s a good thing.”
The USFWS is charged with taking care of Moapa dace which includes estimating their population. Simons, who headed up the Warm Springs count, said the agency conducts the snorkel survey twice a year – in August and February.
“A key requirement for managing the species is to track it through time,” he said. “That’s our way of knowing how things are going for Moapa dace populations.”

A biologist snorkels through shallow spring flows to account for Moapa dace and other fish in the Warm Springs area. Photo by Mike Donahue.
To count the fish wetsuit-clad, goggle-wearing biologists, breathing through snorkels carefully swim upstream noting the numbers of each species of fish they see including any non-natives such as mollies as well as native populations of the Moapa speckled dace, Moapa White River springfish and the Moapa dace. They call out their count to others walking streamside who record the numbers.
Agencies represented last week include biologists and staff from USFWS, Southern Nevada Water Authority (SNWA), the Nevada Department of Wildlife (NDOW), and a graduate student from the University of Arizona.
“It’s a pretty good technique,” Simons said. “When we’ve gone back to double check our numbers (with different counters) our counts usually dovetail pretty well.”
Springs and tributaries surveyed included the Apcar Springs, Pedersen Springs, Refuge Springs (also known as Plummer Springs), the North Fork Tributary, South Fork Tributary and Muddy Springs Tributary (on LDS Church property). Waters survey range from a few inches deep down to 6 feet or more.
“During the survey we’re also looking at the life stages of the Moapa dace (larval, juvenile and adult),” said Crystal Shanley, a SNWA biologist who plays a major role in the restoration of habitat for the endangered fish. “It’s not an exact age classification as much as it’s a size classification.”
Robert Johnson, a biologist and SNWA manager of the Warm Springs Natural Area where many of the fish were counted, explained Moapa dace populations have been steadily increasing for the past several years despite suffering a catastrophic setback between 2007 and 2008.
“For some unknown reason, the population plummeted from 1,172 in February 2007 to 459 in February 2008,” Johnson said. “Since then, however, we’ve seen through successive counts that they’ve been steadily climbing.”
A member of the Cyprinidae family and the sole species in the genus Moapa, the Moapa dace lives only in the warm springs of the upper Muddy River and has a distinctive leathery appearance — hence the scientific name coriacea , which means “leathery,” according to the Center for Biological Diversity’s website.
When first discovered in 1938, the dace was considered common, all living within a 10-mile range that included 25 thermal springs, the website says. “Today its habitat is limited to three springs and a less-than two-mile stretch of the Muddy River.”
Moapa dace has been under protection since 1967, actually predating the Endangered Species Act by six years.
The only areas where Moapa dace are currently found include springs, streams and tributaries in the Moapa Valley National Wildlife Refuge, on private land owned by the LDS Church and on a 1,220-acre tract SNWA purchased for $69 million in 2007 directly across the Warm Springs loop road from the refuge, Johnson said. All areas include thermal waters from the White River Ground-water Flow System which bubble to the surface from several primeval springs.
The 116 acres that make up the wildlife refuge was purchased in 1979 by the USFWS in an effort to protect the species.
“About 85 percent of the dace habitat is on SWNA property, although the majority of the source population of the fish is on USFWS refuge property,” Johnson said.
SNWA and USFWS, with help from other agencies including the Nevada Department of Wildlife (NDOW) which participated in the recent count, have been doing substantial habitat restoration in an effort return the area to its original most native state.
“I’m not talking about the ‘historic’ state of the habitat,” Simons said, “because in recent history there were man-made swimming pools here. We’re talking about returning the habitat to what it was like originally.”
“The USFWS has a recovery plan and we’re (SNWA) trying to assist in the implementation of action that helps meet the goals of that plan,” Johnson said.
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