Spawning ecology and captive husbandry of endangered Moapa Dace

Authors: Jack E. Ruggirello, Scott A.* Bonar, Olin G. Feuerbacher, Lee Simons, Chelsea Powers

Year: 2015 (xlvii)

Abstract

Moapa Dace Moapa coriacea is a critically endangered cyprinid endemic to the Warm Springs area of Clark County, Nevada. Prior to this work, Moapa Dace had never been successfully held in captivity for any length of time, or propagated in captivity. To develop a protocol for rearing and propagation, 40 fish were collected in February 2013, and an additional group of 30 fish were collected in January 2014. We were able to successfully transport and rear Moapa Dace employing slow acclimation and aggressive prophylactic treatment; feeding adults with a combination of live and frozen invertebrates and commercially available pelleted foods; and providing an artificial stream environment to them. To spawn Moapa Dace, we applied 15 different treatments, including introduction of different types of cover and different sized substrates; manipulations of photoperiod, water chemistry, and temperature; application of hormone baths and injections, and manipulation of water flow. We were finally able to propagate Moapa Dace in two different artificial streams using a water flow modification treatment provided over three months. This treatment differed from all others in that it employed a submersible pump at the bottom - in addition to the surface flow - to deliver a lateral flow of water along the gravel substrate into a cobble bed. The conditions we used to successfully rear and propagate Moapa dace (artificial stream environment, provided cover; 30-32Á‚°C stream temperatures; water depths of 32-49 cm, and adequate flow directed along the bottom into cobble substrate) were similar to conditions where we saw Moapa Dace spawn in the wild using underwater videography. Our study suggests proper conditions in which to rear and propagate Moapa Dace are specific, spawning cues are subtle, and propagation can be difficult. Furthermore, alteration of flow, temperature, substrate and other conditions found in natural streams may affect conditions needed for successful spawning in the wild.