David R. Stewart

Statistician (Biology)
Regional Office, Albuquerque
Phone: 505-248-6642
Email: David_Stewart at fws.gov

“… the actual and physical conduct of an experiment must govern the statistical procedures of its interpretation.” – R. A. Fisher

Scientific Interests:

I specialize in applying quantitative tools to better understand processes in ecology and management.  My active research focus includes sampling design, design-based estimation, simulations, stock assessment models and evaluating population dynamics, and decision-making.

Current Projects:

Conservation and management of Yaqui fishes – San Bernardino Wildlife Refuge was created to provide endangered and threatened Yaqui fishes (i.e., Yaqui Topminnow, Yaqui Chub, and the Beautiful Shiner) protection.  This work will evaluate the effectiveness of current and alternative sampling designs used to monitor abundance trends in lentic and lotic systems.  Additionally, I will explore simulation models to simulate meta-population dynamics of each species to examine the use of translocations as a management option by estimating the stability, resilience, and sustainability of the populations.  This work will increase the utility and interpretation of abundance trends, and simulation models will allow us to explore multiple questions related to management of Yaqui fishes.

A simulation model to explore Yaqui Catfish management strategies – The Yaqui Catfish is an imperiled species that is endemic to three drainage basins.  It is critical to explore population management strategies to evaluate long-term sustainability, given that no reproduction has been observed in the Rio Yaqui drainage basin, suggesting using theory and assessment methods is needed.  Using simulation modeling is commonplace in fisheries to explore a diversity of ecological and applied questions about fish populations, and serves as an important role in stock assessment models for analyzing long-term sustainability of the two Yaqui Catfish populations located at San Bernardino Wildlife Refuge.  I will first explore population dynamics of these populations at their current low recruitment rates, and then evaluate the dynamics of stock enhancement (releasing hatchery-reared fish) and its potential role at increasing long-term sustainability of Yaqui Catfish.

A simulation model to explore the effects of climate change on sustainability of salmonids – Growth and mortality of salmonids is a local adaptation that is expected to be influenced by climate change.  Many studies have illustrated range contraction and expansion of salmonids with increasing water temperatures, given the variability in response among species.  However, few studies have sought to examine sustainability of salmonid populations.  This project will use simulation models to explore population sustainability of the Rio Grande Cutthroat Trout, Brown Trout, and Brook Trout located in the southernmost range of the Rocky Mountains.

Education:
Ph.D., 2013, Oklahoma State University, Natural Resource Ecology and Management (Statistics)
M.Sc., 2009, Middle Tennessee State University, Biology (Biometrics)
B.Sc., 2006, Martin Methodist College, Biology (Pre-Medicine)

Awards, Scholarships, and Fellowships:

  • 2016: U.S. Fish and Wildlife Service – Southwest Region Early Career Professional of the Year
  • 2013: John E. Skinner Memorial Award, American Fisheries Society
  • 2013: Williams Distinguished Graduate Fellowship, Oklahoma State University
  • 2013: Murray-Gray Unit Service Award, Oklahoma Cooperative Fish and Wildlife Research Unit
  • 2013: Outstanding Fisheries Graduate Student Award, Oklahoma State University
  • 2013: Robert M. Jenkins Memorial Reservoir Scholarship, American Fisheries Society
  • 2010-2012: Sitlington Enriched Graduate Fellowship, Oklahoma State University
  • 2010-2013: Graduate Research Assistant Award, Oklahoma Cooperative Fish and Wildlife Research Unit
  • 2008: George C. Murphy Research Grant, Middle Tennessee State University
  • 2008: J. Gerald Parchment Biological Field Station Grant, Middle Tennessee State University

Publications:

  1. Parsley, P. M., D. R. Stewart, and M. G. Gatlin.  In Review.  Aging bias and precision for Brook Trout (Salvelinus fontinalis), Brown Trout (Salmo trutta), and Rio Grande Cutthroat Trout (Oncorhynchus clarki virginalis): an evaluation of non-lethal versus lethal aging structures, and incorporating aging error into growth parameter estimates.
  2. Brewer, S. K., T. A. Worthington, R. Mollenhauer, D. R. Stewart, R. McManamay, L. Georgett, and D. Williams.  In Review.  Synthesizing models useful for ecohydrology and ecohydraulic approaches: An emphasis on integrating models to address complex research questions.
  3. Carlisle, J. D., D. R. Stewart, and A. D. Chalfoun.  In Review.  Habitat prioritization developed for sage-grouse doesn’t align with rangeland ant and lizard abundances.
  4. Stewart, D. R., Z. E. Underwood, F. J. Rahel, and A. W. Walters.  In Review.  Can surrogate taxa be used to conserve freshwater biodiversity?
  5. Stewart, D. R., M. J. Butler, G. Harris, and W. R. Radke.  2017.  Mark-recapture models identify imminent extinction of Yaqui catfish Ictalurus pricei in the United States. Biological Conservation 209:45-53.†Media: YaleEnvironment360, “In Southwest Borderlands, the Yaqui Catfish faces its final days” 23 February 2017 (http://e360.yale.edu/features/in-southwest-borderlands-the-yaqui-catfish-faces-its-final-days) and EarthTouchNews, “Yaqui catfish faces extinction in the US by 2018” 1 March 2017 (http://www.earthtouchnews.com/conservation/endangered/yaqui-catfish-faces-extinction-in-the-us-by-2018).
  6. Stewart, D. R., M. J. Butler, G. Harris, L. A. Johnson, and W. R. Radke. 2017.  Monitoring rare endemic fish populations: Evaluating traditional techniques and improving surveys to eliminate bias from non-constant detectability.  Endangered Species Research 32:187-207.
  7. Long, J. M., D. R. Stewart, D. Balsman, J. Shiftlet, and D. E. Shoup. 2017.  Bait type influences catch and bycatch in tandem hoop nets set in reservoirs. Fisheries Research 186:102-108.
  8. Gibson-Reinemer, D. K., D. R. Stewart, A. Casper, M. W. Fritts, and J. A. DeBoer. 2016.  Estimating the effects of environmental variables and gear type on the detection and occupancy of large river fishes in a standardized sampling program using multi-season Bayesian mixture models.  North American Journal of Fisheries Management 36:1445-1456.
  9. Stewart, D. R., J. M. Long, and D. E. Shoup.  2016.  Simulation modeling to explore the effects of length-based harvest regulations for Ictalurus fisheries. North American Journal of Fisheries Management 36:1190-1204.
  10. Stewart, D. R., J. M. Long.  2016.  Using hierarchical Bayesian multi-species mixture models to estimate tandem hoop-net based habitat associations and detection probabilities of fishes in reservoirs.  Transactions of the American Fisheries Society. 145:450-461.
  11. Stewart, D. R., A. W. Walters, and F. J. Rahel.  2016.  Landscape-scale factors influencing native and nonnative Great Plains fish distributions.  Diversity and Distributions 22:225-238.
  12. Stewart, D. R., and J. M. Long.  2015.  Growth and contribution of stocked channel catfish Ictalurus punctatus (Rafinesque, 1818): the importance of measuring post-stocking performance.  Journal of Applied Ichthyology. doi:10.1111/jai.12797.
  13. Stewart, D. R., and J. M. Long. 2015.  Using an experimental manipulation to determine the effectiveness of a stock enhancement program.  Journal of Freshwater Ecology.  doi:10.1080/02705060.2015.1021715.
  14. Stewart, D. R., J. M. Long, and D. E. Shoup. 2015.  Spatial structuring within a reservoir fish population: implications for management.  Marine and Freshwater Research 66:202-212. doi:10.1071/MF14085.
  15. Stewart, D. R. 2014.  Kansas lotic and lentic conservation and management of Channel Catfish Ictalurus punctatus.  Kansas Fishes.  University of Press Kansas, Lawrence.
  16. Cartabiano, E., D. R. Stewart, and J. M. Long. 2014.  Effect of bait and gear type on channel catfish and turtle bycatch catch statistics in a reservoir.  Journal of Freshwater Ecology. doi:10.1080/02705060.2014.966165. †Media: FishSens Magazine, “Laundry soap-baited trotlines may be the answer to turtle killing catfish nets” 13 January 2015 (http://magazine.fishsens.com/laundry-soap-baited-trotlines-may-answer-turtle-killing-catfish-nets.htm).
  17. Stewart, D. R., G. D. Schotlen, T. N. Churchill, and J. M. Fly.  2012.  Angler opinions of catfish management in Tennessee.  Proceedings of the Southeastern Association of Fish and Wildlife Agencies 66:88-93.
  18. Stewart, D. R., and J. M. Long. 2012.  Precision of channel catfish catch estimates in medium size impoundments in Oklahoma.  North American Journal of Fisheries Management 32:1108-1112.
  19. Stewart, D. R., and J. M. Long. 2011. The efficacy of mass-marking channel catfish Ictalurus punctatus fingerlings using oxytetracycline.  Proceedings of the Oklahoma Academy of Science 91:31-36.
  20. Long, J. M., and D. R. Stewart. 2010.  Verification of otolith identity used by fisheries managers for aging channel catfish Ictalurus punctatus.  Transactions of the American Fisheries Society 139:1775-1779.
  21. Stewart, D. R., and G. W. Benz, and G. D. Scholten.  2009.  Weight-length relationships and growth data for blue catfish Ictalurus furcatus among four Tennessee waterbodies.  Proceedings of the Southeastern Association of Fish and Wildlife Agencies 63:140-146.2.
  22. Ulicny, K. J., D. R. Stewart, A. McElwain, E. R. Salmon, S. A. Bullard, J. O. Cook, G. D. Skomal, H. L. Pratt, Jr., and G. W. Benz.  2007.  Sealing Whirl-Pak®-type bags containing wet samples.  Tennessee Academy of Science 88-89.