A simulation model of the Devils Hole pupfish population using monthly length-frequency distributions

The Devils Hole pupfish, Cyprinodon diabolis, is a federally-endangered fish that is endemic to Devils Hole, a discontiguous part of Death Valley National Park in Nye County, Nevada. Due to its status, Devils Hole pupfish monitoring must be non-obtrusive and thereby exclude techniques that require handling fish. Due to a recent decline in pupfish abundance, Devils Hole pupfish managers have expressed a need for a model that describes population dynamics. This population model would be used to identify vulnerable life history stage(s) and inform management actions. We constructed a set of individualbased simulation models designed to explore effects of population processes and evaluate assumptions. We developed a baseline model, whose output best resembled both observed length-frequency data and predicted intraannual abundance patterns. We then ran simulations with 5 % increases in egg-larval, juvenile, and adult survival rates to better understand Devils Hole pupfish life history, thereby helping identify vulnerable life history stages that should become the target of management actions. Simulation models with temporally constant adult, juvenile, and egg-larval survival rates were able to reproduce observed length-frequency distributions and predicted intra-annual population patterns. In particular, models with monthly adult and juvenile survival rates of 80 % and an egg-larval survival rate of 4.7 % replicated patterns in observed data. Population growth was most affected by 5 % increases in egg-larval survival, whereas adult and juvenile survival rates had similar but lesser effects on population growth. Outputs from the model were used to assess factors suspected of influencing Devils Hole pupfish population decline

Developing protocols for in‐water morphometric measurements of cetaceans using stereo‐videogrammetry

Morphometry underpins the basic knowledge of any organism's population demographics and dynamics. Such understanding enables the investigation of trends with important conservation implications including monitoring the health of individuals and changes in population dynamics over time. By detecting declines in health prior to the onset of significant mortality, monitoring of body condition can potentially allow time for a management response to avert population decline. We trialed the use of a diver‐operated stereo‐video (SDOV) system for making morphometric measurements of dwarf minke whales (Balaenoptera acutorostrata subsp.), a small oceanic rorqual, in the Great Barrier Reef, Australia. The SDOV system produced 68% more precise replicate total body length measurements than a single‐camera system, while both systems achieved a mean error below 0.5%. The increased precision offered by a SDOV system is desirable for longitudinal monitoring of growth rates and body condition. Optimal application of this method relied on adherence to protocols for both data collection and analysis beyond those dictated by the equipment user manuals. We provide recommendations for these field and analytical protocols, which may be suitable for use with other cetaceans when in‐water access is available