Use of underwater videography to quantify conditions utilized by endangered Moapa Dace While spawning

Advances in underwater camera technology provide an affordable means to quantify the environmental conditions under which fish spawn. This information is important for investigating spawning ecology, managing habitat, or providing information for captive breeding programs. We deployed 12 modified security cameras underwater to identify environmental conditions related to the spawning behavior of the critically endangered Moapa Dace Moapa coriacea, a Mojave Desert stream-dwelling cyprinid that had never been observed spawning and that had fallen to a low of 459 individual fish 4 years prior to this study. Camera sites were selected systematically along the stream to represent the variety of conditions available. We divided the field of view in front of each camera into a grid, and we estimated both the available environment and the habitat over which Moapa Dace showed spawning behavior. From over 4,000 10-min video clips that were randomly selected for analysis, 13 spawning events were identified. Using nonparametric contingency table analyses, we found that Moapa Dace selected depths between 30 and 34 cm, water velocities between 0.11 and 0.17 m/s, cobble substrate, and overhead instream cover. Although the recorded sample size of spawning events was small (13), our sample represents a large proportion of events given that the world's entire population of Moapa Dace at the time was approximately 650 fish distributed over multiple kilometers of stream length. Environmental conditions identified by this study were replicated in laboratory facilities to successfully propagate Moapa Dace for the first time in captivity. These propagation methods are now used in a management setting by the Nevada Department of Wildlife to maintain a captive population of this rare fish. Camera methods can be effective in helping to identify spawning conditions where water clarity is sufficient.