Ongoing restoration projects for the endangered Moapa dace,?Moapa coriacea, at the Warm Springs Natural Area, Clark County, Nevada

Authors: David Syzdek

Year: 2021

Abstract

The Moapa Warm Springs in Southern Nevada is a regional spring complex that forms the headwaters of the Muddy River. These thermal springs, and associated streams, are habitat for an endemic suite of thermophilic aquatic species that includes the federally-endangered Moapa dace (Moapa?coriacea). Currently, the Southern Nevada Water Authority (SNWA) and other stakeholders are undertaking recovery actions for the Moapa dace and its habitat. These include construction of fish barriers, reduction in or removal of non-native and invasive species, riparian and aquatic habitat restoration, and development of an ecological model for the Moapa dace. To facilitate recovery of the dace and other native species, SNWA purchased the 1,218-acre Warm Springs Ranch in September 2007 and designated it the Warm Springs Natural Area for conservation and environmental stewardship purposes. In 2008, Moapa dace numbers suddenly declined to a record low of 459 individuals. Working with the US Fish and Wildlife Service, Nevada Department of Wildlife (NDOW), and other stakeholders and researchers, SNWA is conducting stream restoration work and intensive habitat improvements to reverse the population’s decline. Following the February 2008 nadir, dace numbers improved somewhat but have yet to reach recovery levels of 6000 fish. Latest snorkel counts recorded 2,444 Moapa dace in August 2021. Since 2008, NDOW and SNWA have successfully treated the Upper Muddy River with rotenone to control the invasive and predatory blue tilapia (Oreochromis?aureus). Furthermore, stream restoration and clearing of dense stands of invasive tamarisk (Tamarix?spp.) and fan palms (Washingtonia?filifera) are facilitating the re-establishment of native riparian vegetation, providing prevention of future wildfires and continued improvement in Moapa dace numbers. In 2015, a removable fish barrier was opened that allows the dace access to its entire historical range. In 2018, additional habitat was acquired on the North Fork with a property purchase and that stream is currently being restored. In 2019 and 2020, 88 Moapa dace were translocated into the South Fork and those fish have successfully reproduced. SNWA, NDOW and USFWS are currently planning a hatchery augmentation program. Moapa dace numbers are currently increasing and work continues to improve dace habitat, improve stream connectivity, and to monitor for invasive species.