Strohm, D.D., Falke, J.A., and Sergeant, C. 2024. Hydrologic regime characterization for wildfire-impacted streams in changing boreal ecosystems. Western Division of the American Fisheries Society Annual Meeting, Honolulu, Hawai’i, 15 – 19, September 2024.
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September 2024
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We used field observations and a hydrologic model to quantify hydrologic regimes in six burned and unburned headwater streams in interior Alaska, and across the Yukon and Kuskokwim basins and the Northwestern Boreal Ecosystem (BYK) in Alaska and Yukon Territory, Canada, respectively. Our hydrologic regime characterization establishes a baseline for boreal streams to aid in identifying stream classes more susceptible to wildfire and facilitate conservation of important boreal aquatic species.
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Stoner, D.C, B. Folt, K.A. Schoenecker. 2024. Can mountain lion predation suppress population growth of feral horses in the American West? International Wild Equids Conference, Nanyuki, Kenya, 8–11 April 2025.
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April 2025
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Management agencies need cost-effective alternatives to manage wild horses populations in the US. We evaluated whether mountain lions could regulate horse populations using simulations and empirical field data. Simulations suggested that 60-80% of foal and yearlings would need to be eaten by lions annually, but field data suggested lion predation was far below that benchmark. Lions may reduce horse population growth by predation, but are unlikely to reduce or stabilize horse population size.
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Shaftel, R., Feddern, M., Shoen, E., Cunningham, C. von Biela, V., McAfee, S., and J. Falke. 2024. Modeled streamflow and stream temperature inform conditions affecting Chinook Salmon in Alaska. American Fisheries Society Annual Meeting, Honolulu, Hawai’i, 15 – 19, September 2024.
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September 2024
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Advances in gridded climate datasets and downscaled climate projections may provide useful tools for quantifying freshwater habitat conditions and predicting effects of climate change on fish populations. We compared several datasets with coverage that ranged from regional to global and found that streamflow and stream temperature model performance varied considerably, but the highest performing models allowed estimation of ecologically relevant conditions affecting Chinook salmon.
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Schoen, E., Feddern, M., Shaftel, R., Harings, M., Reece, K., Kamermans, B., Cunningham, C., Falke, J., and A. López. 2024. Climatic, ecological, and human-driven effects on Yukon-Kuskokwim salmon fisheries. American Fisheries Society Annual Meeting, Honolulu, Hawai’i, 15 – 19, September 2024.
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September 2024
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Salmon populations in Alaska and Canada have declined to historic lows causing unprecedented fisheries closures, management challenges, and profound impacts on subsistence communities. We outline three research efforts that support fisheries managers and communities: environmental drivers of salmon productivity, eDNA as a method to supplement salmon counts, and simulated effects of climate change and wildfire on stream temperature and juvenile salmon growth potential.
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Schoen, E., Falke, J., Paul, J., Meyer, B., Neuswanger, J., Strohm, D., McKenna, B., Lynne, D., and Savereide, J. 2023. How Do Wildfires Affect Alaskan Chinook Salmon? Evidence from Rivers and Satellites. American Fisheries Society Annual Meeting, Grand Rapids, MI, August 20-24, 2023.
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August 2023
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Wildfires are becoming more frequent in Alaska's boreal ecosystems, but their effects on rivers and salmon are not well understood. One year after wildfires bisected an important Chinook salmon habitat, we found fire-affected sites were slightly warmer and more turbid than upstream reference sites, but food resources and juvenile salmon growth were similar. Satellite measurements across a broader study area showed historic wildfires warmed the land surface for > 15 years, resulting in complex e
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Samuel, W. T., J. A. Falke, K. D. Tape, S. K. Panda, A. C. Seitz. 2023. When beavers get burned, do fish get fried? The role of beavers in mediating wildfire effects on freshwater fish habitat in boreal Alaska. American Fisheries Society 153nd Annual Meeting, Grand Rapids, MI. August 20–24.
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August 2023
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Little is known about how wildfire affects fish habitat and populations in boreal streams despite the substantial impacts of fire on ecosystem processes, and how fire effects may be mediated by species interactions. This study will help to provide a better understanding of the role of beavers in maintaining diverse and productive aquatic habitats in riverscapes under changing wildfire conditions.
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Rich, B., Westley, P., Sepulveda, A., Rinella, D., Falke, J., and E. Schoen. 2023. Introduced northern pike predation and consumption of juvenile salmon in a warming world. Matanuska-Susitna Salmon Habitat Partnership Symposium. 13-14 November, 2023. Palmer, AK.
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November 2023
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Global climate change may be exacerbating the impacts of invasive species such as Northern Pike in warming Alaska waters. We found that the direction and rate of predation by pike on juvenile salmon varied by species and with stream flow and temperature, and that pike may switch to alternative prey once salmon are extirpated. Thus, changing freshwater processes may directly affect predation rates of pike on salmon, but not total consumption.
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Rich, B., Sepulveda, A., Falke, J., Schoen, E., Rinella, D., and P. Westley. 2024. Salmon declines coincide with climate mediated increases in consumption by a novel predator. Alaska Chapter American Fisheries Society Annual Meeting. 24-29 March 2024. Seward, AK.
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March 2024
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We explored the potential for synergistic effects of warming and invasion to better understand observed changes in a freshwater community comprised of socially valuable salmonid fishes.
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K. Fitzgerald, L.H. Cheng, N. Boyles-Muehleck, R. Bellmore, J. Fellman, and J. Falke. 2023. Juvenile Coho Salmon growth patterns track biennial Pink Salmon spawning abundance fluctuations in a southeast Alaska watershed. National Meeting of the American Fisheries Society. 20-24 August, 2023,Grand Rapids, MI, USA.
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August 2023
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It is not well known whether adult salmon spawning abundance fluctuations confer disparate foraging and growth opportunities to stream-dwelling fish between years. We explored this hypothesis using a bioenergetic simulation paired with empirical field observations in a southeast Alaskan watershed that supports spawning salmon.
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Hermus, J.H., J.D. Muehlbauer, D.J. Rinella, V.R. von Biela, J.A. Falke. 2023. The effects of water temperature and heat stress on juvenile Chinook Oncorhynchus tshawytscha, and Coho Salmon Oncorhynchus kisutch growth in the Deshka River watershed. Mat-Su Salmon Science and Conservation Symposium, Palmer, Alaska, 13-14 November 2023.
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November 2023
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This presentation is an introduction to John Hermus’ master’s thesis. This project will analyze data from the Deshka River watershed, with the goal of understanding the effects of water temperature and heat stress on juvenile Chinook and Coho Salmon growth in the face of a changing climate.
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Hermus, J.H., J.D. Muehlbauer, D.J. Rinella, V.R. von Biela and J.A. Falke. 2024. The effects of water temperature and heat stress on juvenile Chinook (Oncorhynchus tshawytscha), and Coho Salmon (Oncorhynchus kisutch) growth in the Deshka River watershed. Alaska Chapter American Fisheries Society Annual Meeting, Seward, Alaska, 25-29 March 2024.
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March 2024
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This presentation is an introduction to John Hermus’ masters thesis. This project will analyze data from the Deshka River watershed, with the goal of understanding the effects of water temperature and heat stress on juvenile Chinook and Coho Salmon growth in the face of a changing climate.
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Harings, M.A.B., E. Schoen, B. Kamermans, K. Reece, J. Falke, A. Matter, B. McKenna, N. Farnham, Nicole, S. T. Walter, J.A. López. (2024, September 15-19). Evaluating environmental DNA as a complementary technique for assessing Yukon River salmon. American Fisheries Society Annual Meeting, Honolulu, Hawaii, United States.
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September 2024
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Because high streamflow events can render salmon counting equipment inoperable, leading to missed salmon counts throughout the run, we tested a new method to estimate salmon abundance using daily DNA concentrations in river water for two species in the Yukon River basin, Alaska. The long-term vision of this project is to build capacity to support more robust monitoring of fish populations and enhance climate change resilience in salmon assessment throughout Alaska.
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Folt, B., M.L. Crabb, K.A. Schoenecker. 2024. Management and population density influence wild horse population growth in the western United States. International Wild Equid Conference, Nanyuki, Kenya, 8–11 April 2025.
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April 2025
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We measured wild horse population growth in the western US at 35 populations over 8 years. Population growth varied and was reduced by fertility control treatment and population density. Our results provide decision makers with information on population growth rates for local-scale planning and national-scale policy makers with estimates of how an often-debated management practice, fertility control treatment, has reduced horse population growth across the western US.
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Folt, B. M.L. Crabb, and K.A. Schoenecker. 2024. Population growth of wild horse populations across the western United States. Oral presentation at The Wildlife Society Conference, Baltimore, MD, Oct 2024.
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October 2024
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We built a Bayesian hierarchical state-space model that tested for fixed-effect hypotheses about horse biology and management effects. Preliminary analyses suggested horse population growth rate varies considerably among populations. We discuss how these results might be used to support population management of horse populations in the western United States.
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Fitzgerald, K., R. Bellmore, J. Fellman, C. Delbecq, and J. Falke. 2023. Stream hydrology and a salmon pulse subsidy shape juvenile salmonid foraging patterns in a southeast Alaska watershed. National Meeting of the American Fisheries Society. August 20 -24, 2023, Grand Rapids, MI, USA.
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August 2023
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Consumers capacity to exploit pulse subsidy resources may be influenced by antecedent environmental conditions such as stream flow. For juveniles of two salmonid species, we observed that consumption optima coincided with baseflow and high flow conditions, minima were observed during severe low-water and intermediate flow values, and interannual hydrologic variation shifted growth trajectories among years, potentially impacting access to pulse subsidies.
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Falke, J.A., Dunham, J.B., Rosenberger, A.E., Thurow, R.F., Dolloff, A., Howell, P.J., and W.C. Saunders. 2024. Standardized Sampling of Coldwater Fish in Wadeable Streams in North America. World Fisheries Congress, Seattle, WA. 3-9 March, 2024.
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March 2024
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In this presentation we describe our textbook chapter on standardized techniques for quantitative sampling of fishes in North American coldwater streams focused on backpack electrofishing, snorkeling, and redd count methods. We emphasize training, method validation, and obtaining unbiased measurements and estimates within sampling units as critical components of any coldwater stream standardized sampling program.
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Falke, J.A., Dunham, J.B., Rosenberger, A.E., Thurow, R.F., Dolloff, A., Howell, P.J., and W.C. Saunders. 2024. Standardized Sampling of Coldwater Fish in Wadeable Streams in North America. American Fisheries Society Annual Meeting, Honolulu, Hawai’i, 15 – 19, September 2024.
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September 2024
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quantitative sampling of fishes in North American coldwater streams focused on backpack electrofishing, snorkeling, and redd count methods. We emphasize training, method validation, and obtaining unbiased measurements and estimates within sampling units as critical components of any coldwater stream standardized sampling program.
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Falke, J.A. and J.D. Paul. 2023. Landscape-scale prediction of freshwater habitat potential for Chinook Salmon (Oncorhynchus tshawytscha) across the Yukon and Kuskokwim River basins, Alaska. American Fisheries Society Annual Meeting, Grand Rapids, MI. 20 – 24 August 2023.
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August 2023
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Research into environmental factors involved in the decline of Yukon River Chinook Salmon stocks has exposed information gaps regarding fine-scale freshwater habitat quality known to influence population productivity. We developed spatially-explicit habitat suitability models for spawning and rearing life-stages based on fluvial geomorphic attributes, and are developing a decision support tool based on input from stakeholders tailored to the specific applications of this dataset.
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Falke, J.A. 2024. What is the Nevada Cooperative Fish & Wildlife Research Unit? Graduate Education, Collaborative Research, and Technical Assistance for Fish and Wildlife Conservation and Management in Nevada and Beyond. California-Nevada Chapter American Fisheries Society Biennial Meeting. 9-12 April, 2024, Redding, CA.
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April 2024
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Description of the Nevada Cooperative Fish and Wildlife Research Unit.
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Falke, J.A. 2023. What is the Nevada Cooperative Fish & Wildlife Research Unit? Graduate Education, Collaborative Research, and Technical Assistance for Conservation of Great Basin Fish and Wildlife. Desert Fishes Council Annual Meeting. 15-18 November, 2023, Bishop, CA.
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November 2023
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Description of the Nevada Cooperative Fish and Wildlife Research Unit.
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Falke, J., Schoen, E., Paul, J., and D. Strohm. 2024. Implications of wildfire on stream thermal regimes and juvenile salmon growth in interior Alaska boreal streams. American Fisheries Society Annual Meeting, Honolulu, Hawai’i, 15 – 19, September 2024.
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September 2024
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We investigated the effects of wildfire on stream temperature and juvenile salmon growth using remote sensing, downscaled climate models, and a spatially explicit riverscape bioenergetics approach calibrated with field water temperature, fish growth, and diet data for a ~20,000 km<sup>2</sup> boreal stream network in interior Alaska. These findings provide insights into the effects of wildfire on watersheds and salmon in the boreal forest ecoregion.
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