Spawning ecology of the endangered Moapa dace revealed through underwater videography

Authors: Jack E. Ruggirello, Scott A. Bonar, Olin G. Feuerbacher

Year: 2013 (xlv)

Abstract

Moapa dace, Moapa coriacea, are a critically endangered cyprinid endemic to the Warm Springs area of Clark County, Nevada. Because of its limited range, low abundance, and impacts from introduced species, Moapa dace were federally listed as an endangered species within thirty years of being described. Spawning by Moapa dace has never been documented. Further knowledge of its spawning ecology will be important for identifying factors that induce spawning in captivity and will provide vital data for managers to utilize in habitat improvement projects. We installed twelve underwater cameras, one every ten meters, in the uppermost reach of Plummer Stream. Cameras were equipped with infrared light to record both day and night activity. Camera sites were randomly selected to represent a variety of habitat-types (i.e. pools, glides, runs, and riffles). We quantified available habitat by dividing the field of view in front of each camera into a grid to measure size and embeddedness of substrate, depth, stream velocity, and categorize cover. We recorded approximately 21,000 hours of video from March through May 2012. We randomly selected sixteen 10-minute video clips in every 24-hour period, from each camera, to analyze for spawning activity. Based on activity reviewed to date, Moapa dace appear to be broadcast spawners. Spawning events were recorded in four sites; two in a run, six in a glide, and five in a pool. Four spawning events occurred between 7:00am to 9:00am, one during the noon hour, and nine between 2:00pm and 8:00pm. Locations of spawning events were predominantly in open water, velocities from 0.3 to 0.4 m/sec, depths from 30 to 45 cm, and over silt/clay and cobble substrate.