Annika Walters

Annika Walters

Annika Walters

Annika has been the Assistant Unit Leader for Fisheries at the WY coop unit since 2011. She is an applied aquatic ecologist with research interests in population and community ecology, fisheries, and conservation biology. Annika has an undergraduate degree in Ecology and Evolutionary Biology from Princeton University and a MS and PhD in Ecology and Evolutionary Biology from Yale University. She has conducted research on a variety of topics including low flow disturbance, nutrient loading by anadromous alewife, the effects of climate change and water diversion on salmon, and phenology of phytoplankton communities. She and her students are currently working across the state of Wyoming addressing topics related to oil and natural gas development, multiple stressors, flow alteration, fish movement, and native fish conservation. Much of her research focuses on improving our understanding of how anthropogenic disturbance affects aquatic communities. She works closely with agency cooperators across the state to address questions that can help inform the management of fishes and aquatic ecosystems.


Professional Preparation and Appointments


Ph.D., Ecology and Evolutionary Biology, Yale University, New Haven, CT
Thesis: Community and ecosystem level impacts of disturbance in streams

M.S., Yale University, New Haven, CT

B.A., Princeton University, Princeton, NJ

Professional appointments

2018 – present

2011 – 2018

Associate Professor, Department of Zoology and Physiology, University of Wyoming

Assistant Professor, Department of Zoology and Physiology, University of Wyoming

2011 – present Assistant Unit Leader – Fisheries, USGS Wyoming Cooperative Fish and Wildlife Unit
2011 NSF Bioinformatics Postdoctoral Fellow, School of Aquatic and Fishery Sciences, University of Washington, Seattle
2009-2010 NRC Postdoctoral Research Associate, NOAA Northwest Fisheries Science Center, Seattle, Washington


Google Scholar

Baldock, J.R., R. Al-Chokhachy, M.R. Campbell, and A.W. Walters. 2023. Timing of reproduction underlies fitness trade-offs for a salmonid fish. Oikos e10184 ViewPDF

Messager, M.L., J.D. Olden, J. Tonkin, R. Stubbington, J.S. Rogosch, M.H. Busch, C.J. Little, A.W. Walters, C.L. Atkinson, M. Shanafield, S. Yu, K. Boersma, D. Lytle, R.H. Walker, R.M. Burrows, T. Datry. 2023. A metasystem approach to designing environmental flows. Bioscience. biad067 ViewPDF

Ruthven, J.S., and J. Leonard, and A.W. Walters. 2023. Assessment of invasive Brook Stickleback Culaea inconstans occupancy, habitat drivers, and overlap with native fishes in the North Platte River drainage, Wyoming. Hydrobiologia ViewPDF

Combrink, L.L., W.C. Rosenthal, L.J. Boyle, J.A. Rick, A.C. Krist, A.W. Walters, and C.E. Wagner. 2023. Parallel shifts in trout feeding morphology suggest rapid adaptation to alpine lake environments. Evolution 77(7): 1522-1538. ViewPDF

Newkirk, B.M., E.R. Larson, A.D. Walker, and A.W. Walters. 2023. Winners and losers over a half century of change in crayfish communities of Wyoming, U.S.A. Freshwater Science 42(2): 146-160. ViewPDF

Ruthven, J.S., and A.W. Walters. 2023. Invasive Brook Stickleback Culaea inconstans has limited effects on the trophic ecology of native fishes in Wyoming, USA. Food Webs 35 e00275. ViewPDF

Baldock, J.R., R. Al-Chokhachy, T.E. Walsworth, and A. Walters. 2023 Redd superimposition mediates the accuracy, precision, and significance of redd counts for cutthroat trout. Canadian Journal of Fisheries and Aquatic Sciences. ViewPDF

Datry, T., A. Truchy, J.D. Olden, M.H. Busch, R. Stubbington, W.K. Dodds, S. Zipper, S. Yu, M.L. Messager, J. Tonkin, K. Kaiser, J. Hammond, E.K. Moody, R.M. Burrows, R. Sarremejane, A. DelVecchia, M.L. Fork, C.J. Little, R.H. Walker, A.W. Walters, D. Allen. 2023. Causes, responses, and implications of anthropogenic versus natural flow intermittence in river networks. BioScience 73(1): 9-22. ViewPDF

Fennell, J.M., W.C. Rosenthal, C.E. Wagner, J.C. Burckhardt, and A.W. Walters. 2023. Temporal segregation in spawning between native Yellowstone cutthroat trout and introduced rainbow trout. Ecology of Freshwater Fish 32(1): 94-106. ViewPDF

Wenger, S.J., E.S. Stowe, K.B. Gido, M.C. Freeman, Y. Kanno, N.R. Franssen, J.D. Olden, N.L. Poff, A.W. Walters, P.M. Bumpers, M.C. Mims, M.B. Hooten, and L. Lu. 2022. Simple statistical models can be useful for testing hypotheses with population time series data. Ecology and Evolution 12(9): e9339 ViewPDF

Rosenthal, W.R., J.M. Fennell, E.G. Mandeville, J.C. Burckhardt, A.W. Walters, and C.E. Wagner. 2022. Effects of reproductive fitness in a hybridizing trout population. Molecular Ecology 31(16): 4224-4241. ViewPDF

Barrile, G. M., Chalfoun, A. D, Estes-Zumpf, W., and Walters, A. W. 2022. Wildfire influences individual growth and breeding dispersal, but not survival and recruitment in a montane amphibian. Ecosphere, 13(8), e4212. ViewPDF

Freeman, M.C., K.R. Bestgen, D. Carlisle, E.A. Frimpong, N.R. Franssen, K.B. Gido, E. Irwin, Y. Kanno, C. Luce, A.K. McKay, M.C. Mims, J.D. Olden, N. L. Poff, D.L. Propst, L. Rack. A.H. Roy, E.S. Stowe, A.W. Walters, and S.J., Wenger. 2022. Towards improved understanding of streamflow effects on freshwater fisheries. Fisheries 47(7): 290-298. ViewPDF

Barrile, G. M., Walters, A. W., and Chalfoun, A. D. 2022. Stage-specific environmental correlates of reproductive success in Boreal Toads (Anaxyrus boreas boreas). Journal of Herpetology, 56(1), 34–44. ViewPDF

Booher, E. and A.W. Walters. 2022. Identifying translocation sites for a climate relict population of Finescale Dace (Chrosomus neogaeus). Transactions of the American Fisheries Society 151(2): 245-259 10.1002/tafs.10348 ViewPDF

M.A. Kirk, B.M. Maitland, B.T. Hickerson, A.W. Walters, and F.J. Rahel. 2022. Climatic drivers and ecological impacts of a rapid range expansion by non-native smallmouth bass in a Wyoming river. Biological Invasions 24: 1311-1326. ViewPDF

Alford, S.A. and A.W. Walters. 2022. Rapid post-disturbance colonisation contributes to native fish resilience. Ecology of Freshwater Fish View PDF

Barrile, G.M., A. D. Chalfoun, and A.W. Walters. 2021. Livestock grazing, climatic variation, and breeding phenology jointly shape disease dynamics and survival in a wild amphibian. Biological Conservation 261: 109247. View PDF

LeCheminant A.G., G.M. Barrile, S.E. Albeke, A.W. Walters. 2021. Movement dynamics and survival of stocked Colorado River cutthroat trout Oncohynchus clarkii pleuriticus. Transactions of the American Fisheries Society View PDF

Barrile, G.M., A.W. Walters, M. Webster, and A.D. Chalfoun. 2021. Informed breeding dispersal following stochastic changes to patch quality in a pond-breeding amphibian. Journal of Animal Ecology  View PDF

B.J. Nordberg, E.G. Mandeville, A.W. Walters, J.C. Burckhardt, and C.E. Wagner. 2021. Historical data illustrate the complex effects of stocking in Cutthroat Trout populations. North American Journal of Fisheries Management View PDF

Booher, E. and A.W. Walters. 2021. Biotic and abiotic determinants of finescale dace distribution at the southern edge of their range. Diversity and Distributions 27: 696-709.  View PDF

Barrile, G.M., A.D. Chalfoun, A.W. Walters. 2021. Infection status as the basis for habitat choices in a wild amphibian. American Naturalist 197: 128-137.  View PDF

Walker, R.H., C.E. Girard, S.L. Alford, and A.W. Walters. 2020. Anthropogenic land-use change intensifies the effect of low flow on stream fishes. Journal of Applied Ecology 57: 149-159. View PDF

Ciepiela, L.R., and A.W. Walters. 2019. Life-history variation of two inland salmonids revealed through otolith microchemistry analysis. Canadian Journal of Fisheries and Aquatic Sciences 76(11):1971-1981 View PDF

Hickerson, B.T., B.M. Maitland, and A.W. Walters. 2019. Effects of multiple nonnative predatory fish on an imperiled cyprinid, Hornyhead Chub (Nocomis biguttatus). Transactions of the American Fisheries Society 148: 1132-1145, View PDF

Walker, R.H. and A.W. Walters. 2019. A mechanistic understanding of ecological responses to anthropogenic surface disturbance in headwater streams. Ecosphere 10(10):e02907. View PDF

Mandeville, E.G., A.W. Walters, B.J. Nordberg, K.Higgins, J.C. Burkhardt, and C.E. Wagner. 2019. Genomic outcomes of trout hybridization vary with stocking history. Molecular Ecology 28: 3738-3755 View PDF

Mandeville, C.P., F. Rahel, L.S. Patterson, and A.W. Walters. 2019. Applying threshold analysis to identify stream fish thermal guilds for water temperature regulation. Transactions of the American Fisheries Society 148(4): 739-754. View PDF

Ciepiela, L.R., and A.W. Walters. 2019. Quantifying ⁸⁷Sr/⁸⁶Sr temporal stability and spatial heterogeneity for use in tracking fish movement. Canadian Journal of Fisheries and Aquatic Sciences. View PDF

Walters, A.W., C.E. Girard, R.H. Walker*, A. Farag, and D. Alvarez. 2019. Multiple approaches to surface water quality assessment provide insight for small streams experiencing oil and natural gas development. Integrated Environmental Assessment and Management 9999:1-13. View PDF

Hickerson, B.T. and A.W. Walters. 2019. Evaluation of potential translocation sites for an imperiled cyprinid, Hornyhead Chub (Nocomis biguttatus). North American Journal of Fisheries Management 39:205-218. View PDF

Walters, A.W., C. Peterson, F. Rahel. 2018. The interaction of exposure and sensitivity determines fish species vulnerability to warming stream temperatures. Biology Letters 14:20180342. org/10.1098/rsbl.2018.0342. View PDF

Girard, C.E. and A.W. Walters. 2018. Evaluating relationships between fishes and habitat in streams affected by oil and natural gas development. Fisheries Management and Ecology 25: 366-379. View  PDF

Hooley-Underwood, Z., E. Mandeville, P. Gerritty, J. Deromedi, K. Johnson, and A.W. Walters. 2018. Combining genetic, isotopic, and field data to better describe movement and entrainment of burbot (Lota lota). Transactions of the American Fisheries Society 147: 606-620. doi/10.1002/tafs.10062. View PDF

Stewart, D.R., Z.E. Underwood*, F.J. Rahel, and A.W. Walters. 2018. The effectiveness of surrogate taxa to conserve freshwater biodiversity. Conservation Biology 32: 183-194. doi/10.1111/cobi.12967. View PDF

Walters, A.W., Mandeville, W.C. Saunders, P. Gerrity, J. Skorupski, Z. Underwood*, E. Gardunio. 2017. Comparison of burbot population dynamics across adjacent native and invaded ranges. Aquatic Invasions 12: 251-262 View PDF

Gsell, A.S., Scharfenberger, U., D. Özkundakci, A.W. Walters, L. Hansson, P. Nõges, P.C. Reid, D.E. Schindler, E. van Donk, V. Dakos, R. Adrian. 2016. Early-warning signals foreshadow regime shifts in natural aquatic ecosystems. PNAS doi: 10.1073/pnas.1608242113. View PDF

Walters, A.W. 2016. The importance of context dependency for understanding the effects of low flow events on fish. Freshwater Science 35:216-228 doi:10.1086/683831. View PDF

Stewart, D.R., A,W. Walters, and F. Rahel. 2016. Factors influencing native and nonnative Great Plains fishes in Wyoming. Diversity and Distributions 22:225-238 doi: 10.1111/ddi.12383. View PDF

Underwood, Z.*, E. Mandeville, and A.W. Walters. 2016. Population connectivity and genetic clustering of burbot populations in the Wind River Basin, Wyoming. Hydrobiologia 765:329-342 doi: 10.1007/s10750-015-2422-y. View PDF

Senecal, A. C., A. W. Walters, and W. A. Hubert. 2015. Historical data reveal fish assemblage shifts in an unregulated prairie river. Ecosphere 6(12):287. View PDF

Entrekin, S., K.O. Maloney, K. Kapo, A.W. Walters, M. Evans-White, K. Klemov. 2015. Stream vulnerability to widespread and emergent stressors: a focus on unconventional oil and gas. PLoS ONE 10(9): e0137416. doi:10.1371/journal.pone.0137416. View PDF

Godwin, B.L., S.E. Albeke, H.L. Bergman, A. Walters, and M. Ben-David. 2015. Density of river otters (Lontra canadensis) in relation to energy development in the Green River Basin, Wyoming. Science of the Total Environment 532:780-790. View PDF

Pantel, J., D. Pendleton, A. Walters, and L. Rogers. 2014. Linking environmental variability to population and community dynamics. p. 119-131. In P.F. Kemp [ed.], Eco-DAS IX Symposium Proceedings. ASLO. [doi: 10.4319/ecodas.2014.978-0-9845591-3-8.119]. View PDF

Walters, A.W., K.K. Bartz, and M.M. McClure. 2013. Interactive effects of water diversion and climate change for juvenile Chinook salmon in the Lemhi River. Conservation Biology 27:1179-1189. View PDF

Walters, A.W., M.A.G. Sagrario, and D.E. Schindler. 2013. Species and community level responses combine to drive phenology of lake phytoplankton. Ecology 94:2188-2194. View PDF

Walters, A.W., T. Copeland, and D.A. Venditti. 2013. The density dilemma: limitations on juvenile production in threatened salmon populations. Ecology of Freshwater Fish 22:508-519. View PDF

Walters, A.W., D. M. Holzer, J. R. Faulkner, C. D. Warren, P. D. Murphy, and M.M. McClure. 2012. Quantifying cumulative entrainment effects for Chinook salmon in a heavily irrigated watershed. Transactions of the American Fisheries Society 141:1180-1190. View PDF

Walters, A.W. 2011. Resistance of aquatic insects to a low flow disturbance: exploring a trait-based approach. Journal of the North American Benthological Society 30: 346-356. View PDF

Walters, A.W. and D.M. Post. 2011. How low can you go? Response of aquatic insect communities to low flow disturbance. Ecological Applications 21:163-174. View PDF

West, D., A.W. Walters, S. Gephart, D.M. Post. 2010. Nutrient loading by anadromous alewives: contemporary patterns and predictions for restoration efforts. Canadian Journal of Fisheries and Aquatic Sciences 67: 1211-1220. View PDF

Walters, A.W., R.T. Barnes, and D.M. Post. 2009. Anadromous alewife contribute marine-derived nutrients to coastal stream food webs. Canadian Journal of Fisheries and Aquatic Sciences 66:439-448. View PDF

Post D.M. and A.W. Walters. 2009. Nutrient excretion rates of anadromous alewives during their spawning migration. Transactions of the American Fisheries Society 138: 264-268. View PDF

Walters, A.W. and D.M. Post. 2008. An experimental disturbance alters fish size structure, but not food chain length in streams. Ecology 89: 3261-3267. View PDF