Biologists Log A Healthy Jump In Moapa Dace Numbers - mvprogress

By VERNON ROBISON

The Progress

Dr. David Stone of the US Fish and Wildlife Service snorkels through the South Fork area of the Warm Springs Natural Area looking for the endangered Moapa dace. Photo courtesy David Syzdek.

All of the turmoil of 2020 has seemed to have no effect on the endangered Moapa dace. The little finger-length fish that lives only in the Warm Springs headwaters of the Muddy River has actually had an outstanding year. According to a scientific study earlier this month, the dace has multiplied its numbers significantly and also expanded its range into areas where the little fish hasn't been seen in a long time.

Biologists conducting the annual summer snorkel survey of the entire spring system counted a total of 2,342 dace this month. That represents an increase of nearly 78 percent over the number of 1,317 fish counted in Aug. 2019. This was the highest dace population observed since the August count was begun in 2008.

It was also the first time since August 2015 that the dace population has topped 2,000 fish. In the years since 2015, the annual summer count has seen a small decline.

"The recent population count is very encouraging," said Glen Knowles, field supervisor for the U.S. Fish and Wildlife Service Southern Nevada office. "We are especially happy about the increases in the population in the system outside the boundary of the Moapa Valley National Wildlife Refuge."

That included population growth in streams lying within the Warm Springs Natural Area, owned and managed by Southern Nevada Water Authority (SNWA).

The SNWA began restoring dace habitat on its 1,179-acre Natural Area shortly after it was acquired for that purpose in 2008. At that time there were fewer than 500 dace in the whole system.
SNWA biologist David Syzdek, who helps oversee the annual count, said that it was exciting to see the expanded range of the fish.

"Not only were the fish numbers very high in all the reaches that typically have Moapa dace," Syzdek said. "But it was also very exciting to finally see groups of dace in areas of the Main Stem where I have never seen any Moapa dace before."

Syzdek explained that last year scientists had translocated 88 dace into a segment of the stream called the South Fork, where previous counts had always found no fish. This month's count observed 201 fish in that segment of the river.

"It is fantastic to see this population successfully reproducing in a stream that had zero dace for so many years," Syzdek said.

Record numbers of dace were also counted in several other streams in the area. The Lower Apcar Stream had 227 dace; the Lower Refuge Stream, 175; Lower Muddy River, 15 dace; Middle Muddy River, 9 dace; Muddy Creek (Church of Jesus Christ of Latter-day Saints at Warm Springs Recreation Camp) 133 dace; and South Fork, 201 dace.

Another landmark with this year's count was a dramatic increase in the number of adult fish observed. This year a total of 1,521 adults were found. That compared to the 2019 count of 1,085 adults.
"This indicates that more larvae and juveniles are reaching adulthood," Syzdek said. "These adults will hopefully produce more eggs and young in the future."

While these numbers are promising, full recovery of the species is still a long way off. The dace will not be considered fully recovered until the fish's sustained population reaches a minimum of 6,000 fish over a period of five consecutive years. In addition, 75 percent of its historical habitat in the upper Muddy ecosystem must provide spawning, nursery, cover and foraging habitat for the species.

"We still have a long way to go," Syzdek said. "But this was great news. It was good to see the numbers high across all the places we saw fish."