Devils Hole Pupfish Population Dynamics: Estimating Growth and Survival from Length-Frequency Data

The Devils Hole pupfish Cyprinodon diabolis is a federally-endangered fish that is endemic to Devils Hole, Nye County, NV.  Due to its endangered status, Devils Hole pupfish monitoring must be non-obtrusive and thereby exclude techniques that require handling fish.  While certain aspects of Devils Hole pupfish ecology have been studied extensively, knowledge of Devils Hole pupfish life history remains limited.  In early 2009, the National Park Service acquired a SCUBA-diver-operated stereovideo system which can be used to obtain fish lengths from video images.  Beginning in March 2009, the National Park Service initiated monthly SCUBA dives in Devils Hole to generate estimates of length-frequency distributions of the Devils Hole pupfish population.  Because it is difficult to differentiate population processes (e.g., recruitment, survival, growth) without individual histories, we constructed a set of individual-based simulation models designed to explore effects of population processes and evaluate assumptions.  Results from simulation models were compared with observed data to assess the credibility of simulation model assumptions.