Population ecology and monitoring of the endangered Devils Hole pupfish

We assessed four potential sources of error in estimating size of the population of Devils Hole pupfish (Cyprinodon diabolis); net, time of day, diver, and order of diver. Experimental dives (3/day) were conducted during 4 days in July 2009. Effects of the four sources of error on estimates from dive surveys were analyzed using a split-split plot ANOVA. Diver and order of diver had no significant influence on estimates, whereas the effect of presence or absence of a net was significant. Effects of time of day and presence or absence of a net showed a significant interaction with depth of water. Results indicated that pupfish may move upward during the dive, and as a result, the standard methods of dive surveys may underestimate abundance. RESUMEN—En este estudio, nosotros organizamos una serie de sesiones de buceo experimentales para evaluar cuatro fuentes de error que posiblemente influyen los cálculos aproximados de la población—la red, la hora del día, el buzo, y el orden de los buzos. Estas sesiones de buceo experimentales incluían cuatro días de buceo en julio de 2009, con tres 1 Graduate student and Associate Professor, respectively, Department of Natural Resource Ecology and Management, Iowa State University. 2 Assistant Unit Leader, U.S. Geological Survey Idaho Cooperative Fish and Wildlife Research Unit, University of Idaho. 3 Professor, Department of Statistics, Iowa State University. 4 Fish biologist, U.S. Forest Service – Bighorn National Forest. 5 Aquatic biologist and fish biologist, respectively, U.S. Park Service – Death Valley National Park.