Estimating Devils Hole Pupfish Lifestage Ratios Using the Delphi Method

Devils Hole pupfish (Cyprinodon diabolis) is one of the rarest and most restricted vertebrates in the world. It exists in a single location in southwest Nevada and in recent years the population has fluctuated between 38 and 95 individuals. To better inform population dynamics models and decision support efforts, the Delphi method was used to iteratively query six experts on lifestage ratios of the species. Expert estimations for egg production changed significantly during the exercise. If experts do not reach consensus for a given parameter, it can be taken as an index of uncertainty and an area requiring more quantitative research. The Delphi method proved to be valuable when decisions must be made in lieu of empirical information but should not be used as a Substitute for pursuing those data.