By MAGGIE MCMURRAY
Moapa Valley Progress
The Southern Nevada Water Authority (SNWA) conducted its semi-annual count of the endangered Moapa dace last week. The only place in the world the Moapa dace is located is in the warm waters of the upper Muddy River and the springs that feed into it.
SNWA, in conjunction with the Nevada Department of Wildlife and the US Fish and Wildlife Service, conducts a count of the small, finger-sized, fish twice a year. The first count takes place annually in February. The second occurs in late August or early September.
Counts are timed to avoid the late spring breeding season for the dace. The February count numbers the fish that made it through winter. The August count is timed to let biologists know how the breeding season went.
Dace numbers in August are typically higher than those in February. So scientists track two sets of numbers, looking from February to February to judge trends in the adult population, and August to August to judge how breeding seasons have gone.
This year’s count showed a solid 1,533 fish in the Warm Springs streams. That number was down from last year’s August count of 1,635. But is still within a stable range, according to SNWA Biologist David Syzdek.
“We’ve had a pretty stable population since about 2012,” Syzdek explained. “It fluctuates between about 1,000 and 2,000, but stays in that range. This year we saw lots of babies, which made us very happy.”
Conducting the count is an adventure in itself. “It’s a huge interagency effort,” Syzdek said. “We work in teams of two over two days and snorkel over 7 miles of rivers and creeks.”
Syzdek explained that the teams always work upstream in a very carefully choreographed manner that prevents one team from muddying the water and ruining visibility for other teams. The teams snorkel where possible, but many times end up crawling through shallow waters, over rocks, and around and under logs to get an accurate count of all fish in the river system.
While the Moapa dace numbers are of primary concern to the biologists, the teams also count the other fish in the river. The Moapa White River Spring Fish is another native specie that is also found only in the Muddy River and only in the Moapa area. Unlike the dace, however, this specie of fish is very abundant and doing well.
There are also two species of non-native fish that are found in the Warm Springs area. The Short-fin Molly, an aquarium fish originally from Mexico, has been found in the upper Muddy beginning about fifty years ago. The Western Mosquito fish is also found there. In addition, the Muddy river is also home to two other species of native fish: the Virgin River chub and the Moapa Speckled Dace. Neither of these two has been seen for years in the Warm Springs area. But both species are doing well in other areas of the Muddy, Syzdek said.
Dace numbers are continuing to rebound after an all-time low of 459 in February of 2008. The low count was thought to be a direct result of predation by the blue tilapia, an invasive specie that originates in Africa and was discovered in Lake Mead in the early 1990’s. By 1997, the Blue Tilapia had made its way from Lake Mead up the Muddy to the Warm Springs area where it became a major predator of the already endangered dace.
Due to an all-out effort by the Nevada Department of Wildlife, blue tilapia were eradicated in the Warm Springs area by 2013-2014, allowing the Moapa dace numbers to begin to rebound Syzdek said.
Efforts to improve the habitat of the Moapa dace are ongoing. “We’re doing a lot of work to improve fish habitats,” Syzdek said. “We’re planting stream-side vegetation and native plants and working to improve fish passage between the streams.”
Syzdek explained that in order to thrive, it is important that the Moapa dace be able to move from side streams to the main river and back. Biologists have been working hard to facilitate movement for the dace through the area by removing dams that were originally placed to protect the dace from blue tilapia predation but are now no longer necessary.
On another note, the Warm Springs Natural Area will be opening to the public sometime this fall. The area includes a visitor area with restrooms, picnic tables, and a drinking fountain, as well as hiking trails and viewing areas. Across the street from the Natural Area, the Moapa Valley National Wildlife Refuge is already open with similar facilities, more hiking trails, and a stunning live-stream aquarium viewing area where the Moapa dace can be viewed in its natural habitat.
Syzdek encourages the public to come, view, and enjoy the area. “It’s a beautiful area that celebrates and highlights native plants, animals, and fish,” Syzdek said. “We are happy to be part of the community and are looking forward to having visitors when we open later this fall.”
Admission to both areas is free.