Cooperative Research Units
Education, Research And Technical Assistance For Managing Our Natural Resources
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Dr. Tyler Wagner

Research Publications

  • White, S.L., W.L. Miller, S.A. Dowell, M.L. Bartron, and T. Wagner. Accepted. Limited hatchery introgression into wild brook trout (Salvelinus fontinalis) populations despite reoccurring stocking. Evolutionary Applications.
  • Wagner, T. and E.M. Schliep. Combining nutrient, productivity, and landscape-based regressions improves predictions of lake nutrients and provides insight into nutrient coupling at macroscales.
  • Schall, M.K., V.S. Blazer, H.L. Walsh, G.D. Smith, T. Wertz, and T. Wagner. Spatial and temporal variability of myxozoan parasite prevalence in young of the year smallmouth bass in the Susquehanna River Basin, Pennsylvania
  • Yuan, S., J. Zhou, P-N., Tan, E. Fergus, T. Wagner, and P.A. Soranno. 2017. Multi-Level Multi-Task Learning for Nested Geospatial Data. The IEEE International Conference on Data Mining series (ICDM).
  • Stow, C.A., K.E. Webster, T. Wagner, N. Lottig, P.A. Soranno, C. YoonKynug. 2018. Small Values in Big Data: The Continuing Need for Appropriate Metadata. Ecological Informatics 45:26-30.
  • Oliver, S.K., C.E. Fergus, N.K. Skaff, T. Wagner, P-N. Tan, K.S. Cheruvelil, and P.A. Soranno. Strategies for effective collaborative manuscript development in interdisciplinary science teams. Ecosphere.
  • Massie, D.L., G.D. Smith, T.F. Bonvechio, A.J. Bunch. D.O. Lucchesi, T. Wagner. 2018. Spatial variability and macroscale drivers of growth for native and introduced Flathead Catfish populations. Transactions of the American Fisheries Society 147:554-565.
  • Schall, M.K., V.S. Blazer, R.M. Lorantas, G.D. Smith, J.E. Mullican, B.J. Keplinger, T. Wagner. In press. Quantifying Temporal Trends in Fisheries Abundance using Bayesian Dynamic Linear Models: A Case-Study of Riverine Smallmouth Bass Populations. North American Journal of Fisheries Management.
  • Filstrup, C.T., T. Wagner, S.K. Oliver, C.A. Stow, K.E. Webster, E.H. Stanley, and J.A. Downing. 2018. Evidence for regional nitrogen stress on chlorophyll a in lakes across large landscape and climate gradients. Limnology and Oceanography.
  • DeWeber, J.T. and T. Wagner. 2018. Probabilistic measures of climate change vulnerability, adaptation action benefits, and related uncertainty from maximum temperature metric selection. Global Change Biology.
  • Irwin, B., T Wagner, and J. R. Bence. 2018. Characterization of Spatial and Temporal Variability in Fishes in Response to Climate Change. Project completion report [extended abstract], Northeast Climate Science Center.
  • Lottig, N.R., P.-N. Tan, T. Wagner, K.S. Cheruvelil, P.A. Soranno, E.H. Stanley, C.E. Scott, C.A. Stow, and S. Yuan. 2017. Macroscale patterns of synchrony identify complex relationships among spatial and temporal ecosystem drivers. Ecosphere 8(12).
  • Li, Y., T. Wagner, Y. Jiao, R. Lorants, and C.A Murphy. Accepted. Evaluating spatial and temporal variability in growth and mortality for recreational fisheries with limited catch data. Canadian Journal of Fisheries and Aquatic Sciences.
  • Soranno, P.A., L.C. Bacon, M. Beauchene, K.E. Bednar, E.G. Bissell, C.K. Boudreau, M.G. Boyer, M.T. Bremigan, S.R. Carpenter, J.W. Carr and 70 co-authors. LAGOS-NE: A multi-scaled geospatial temporal database of lake ecological context and water quality for thousands of U.S. Lakes. In press. GigaScience.
  • Cheruvelil, S. K., S. Yuan, K.E. Webster, P-N Tan, J.F. Lapierre, S.M. Collins, C.E. Fergus, C.E. Scott, E.N. Henry, P.A. Soranno, C.T. Filstrup, T. Wagner. Creating multi-themed ecological regions for macrosystems ecology: Testing a flexible, repeatable, and accessible clustering method. Ecology and Evolution 7:3046-3058.
  • Oliver, S.k., S.M. Collins, P.A. Soranno, T. Wagner, E.H. Stanley, J.R. Jones, C.A. Stow, and N.R. Lottig. 2017. Unexpected stasis in a changing world: Lake nutrient and chlorophyll trends since 1990. Global Change Biology 23:5455–5467 DOI: 10.1111/gcb.13810
  • Collins, S.M., S.K. Oliver, J.F. Lapierre, E.H. Stanley, J.R. Jones, T. Wagner. and P.A. Soranno. 2017. Lake nutrient stoichiometry is less predictable than nutrient concentrations at regional and sub-continental scales. Ecological Applications 27:1529-1540.
  • Schall, M.K., M.L. Bartron, T. Wertz, J. Niles, V.S. Blazer, and T. Wagner. 2017. Evaluation of genetic population structure of Smallmouth Bass in the Susquehanna River Basin, PA. North American Journal of Fisheries Management 37:729-740.
  • Sweka, J.A., L.A. Davis, T. Wagner. 2017. Fall and winter survival of brook and brown trout in a North-Central Pennsylvania watershed. Transactions of the American Fisheries Society 146:744-752. Download  | 
  • Vidal, T. E., B. J. Irwin, T. Wagner, L. G. Rudstam, J. R. Jackson, and J. R. Bence. 2017. Using Variance Structure to Quantify Responses to Perturbation in Fish Catches. Transactions of the American Fisheries Society 146:584-593. [Featured Article] Abstract | 
  • Hansen, G.J.A., S.R. Midway, T. Wagner. 2017. Walleye recruitment is less resilient to warming water temperatures in lakes with abundant largemouth bass populations. Canadian Journal of Fisheries and Aquatic Sciences.
  • Grossman, G.D., R.F. Carline, and T. Wagner. Brown trout (Salmo trutta) in Spruce Creek Pennsylvania: a quarter-century perspective. 2017. Freshwater Biology 62:1143-1154.
  • Wagner, T. J.B. Whittier, J.T. DeWeber, S.R. Midway, and C.P. Paukert. 2017. Annual changes in seasonal river water temperatures in the eastern and western United States. Water 9(2), 90; doi:10.3390/w9020090
  • Midway, S.R., C.T. Hasler, T. Wagner, and C.D. Suski. 2017. Predation of freshwater fish in elevated carbon dioxide environments. Marine and Freshwater Resources 68:1585-1592.
  • Peoples, B., S.R. Midway, J.T. DeWeber, and T. Wagner. 2018. Catchment scale determinants of nonindigenous minnow richness in the eastern United States. Ecology of Freshwater Fish 27:138-145.
  • Fergus, C.E., A.O. Finley, P.A. Soranno, T. Wagner. 2016. Spatial Variation in Nutrient and Water Color Effects on Lake Chlorophyll at Macroscales. PLoS ONE 11(10): e0164592.doi:10.1371/journal.pone.0164592.
  • White, S.L., T. Wagner, C. Gowand, and V.A. Braithwaite. 2017. Can personality predict individual differences in brook trout spatial learning ability? Behavioural Processes 141:220-228.
  • Midway, S.R., T. Wagner, J.D. Zydlewski, B.J. Irwin, and C.P. Paukert. 2016. Transboundary Fisheries Science: Meeting the Challenges of Inland Fisheries Management in the 21st Century. Fisheries 41:537-546. Download  | 
  • Wagner, T., C.E. Fergus, C.A. Stow, K.S. Cheruvelil, and P.A. Soranno. 2016. The statistical power to detect cross-scale interactions at macroscales. Ecosphere. 7(7):e01417. Download  | 
  • Wagner, T., S.R. Midway, T. Vidal, B.J. Irwin, and J.R. Jackson. 2016. Detecting unusual temporal patterns in fisheries time series data. Transactions of the American Fisheries Society 145:786-794. Abstract |  Download  | 
  • Oliver, S.K., P.A. Soranno, C.E. Fergus, T. Wagner, L.A. Winslow, C.E. Scott, K.E. Webster, J.A. Downing, and E.A. Stanley. 2016. Prediction of lake depth across a 17-state region in the U.S. Inland Waters 6:314-324. Download  | 
  • Davis, L.A. and T. Wagner. 2016. Scale-dependent seasonal pool habitat use by sympatric wild Brook Trout and Brown Trout populations. Transactions of the American Fisheries Society 145:888-902. Download  | 
  • Midway, S.R. and T. Wagner. 2015. The first description of oarfish Regalecus glesne (Regalecidae) ageing structures. Journal of Applied Ichthyology.
  • DeWeber, J.T. and T. Wagner. 2015. Translating climate change effects into everyday language: an example of more driving and less angling. Fisheries 40:395-398. Download  | 
  • Soranno, P.A., K.S. Cheruvelil, T. Wagner, K.E. Webster, and M.T. Bremigan. 2015. Effects of land use on lake nutrients: The importance of scale, hydrologic connectivity, and region. PLoS ONE 10(8): e0135454.
    Download  | 
  • Smith, L.A., T. Wagner, M.L. Bartron. 2015. Spatial and temporal movement dynamics of brook Salvelinus fontinalis and brown trout Salmo trutta. Environmental Biology of Fishes 98:2049-2065. Download  | 
  • Soranno, P.A., E.G. Bissell, K.S. Cheruvelil, S.M. Collins, C.E. Fregus, C.T. Filstrup, J-F. Lapierre, N.R. Lottig, S.K. Oliver, C.E. Scott, N.J. Smith, S. Stopyak, S. Yuan, M.T. Bremigan, J.A. Downing, C. Gries, E.N. Henry, N.K. Skaff, E.H. Stanley, C.A. Stow, P-N. Tan, T. Wagner, and K.E. Webster. 2015. Building a multi-scaled geospatial temporal ecology database from disparate data sources: Fostering open science and data reuse. GigaScience 4:28. Download  | 
  • Midway, S. R., T. Wagner, S. Arnott, P. Biondo, F. Martinez-Andrade, and T. Wadsworth. 2015. Spatial and temporal variability in growth of southern flounder (Paralichthys lethostigma). Fisheries Research 167:323-332.
  • Midway, S., T. Wagner, B. H. Tracy, G. M. Hogue, and W.C. Starnes. 2015. Evaluating changes in stream fish species richness over a 50-year time-period within a landscape context. Environmental Biology of Fishes 98:1295-1309. Abstract | 
  • DeWeber, J.T and T. Wagner. 2015. Predicting Brook Trout occurrence in stream reaches throughout their native range in the eastern United States. Transactions of the American Fisheries Society 144:11-24. Download  | 
  • DePasquale, C., T. Wagner, G.A. Archard, B. Ferguson, and V.A. Braithwaite. 2014. Learning rate and temperament in a high predation risk environment. Oecologia 176:661-667.
  • Wagner, T. and S.R. Midway. 2014. Modeling spatially varying landscape change points in species occurrence thresholds. Ecosphere 5(11):145. Download  | 
  • Kepler, M.V., T. Wagner, and J.A. Sweka. 2014. Comparative bioenergetics modeling of two Lake Trout morphotypes. Transactions of the American Fisheries Society 143:1592–1604. Download  | 
  • Midway, S. M., T. Wagner. and Tracy, B. 2014. A hierarchical community occurrence model for North Carolina stream fish. Transactions of the American Fisheries Society 143:1348-1357. Download  | 
  • Filstrup, C.T., T. Wagner, P.A. Soranno, E.H. Stanley, C.A. Stow, K.E. Webster, and J.A. Downing. 2014. Regional variability among nonlinear chlorophyll-phosphorus relationships in lakes. Limnology and Oceanography 59:1691-1703. Abstract |  Download  |  Publisher Website | 
  • Perles, S. J., T. Wagner, B. J. Irwin, D. R. Manning, K. K. Callahan, and M. R. Marshall. 2014. Evaluation of a regional monitoring program's statistical power to detect temporal trends in forest health indicators. Environmental Management 54:641-655. doi:10.​1007/​s00267-014-0313-z Download  | 
  • Deweber, J.T. and T. Wagner. 2014. A regional neural network model for predicting mean daily river water temperature. Journal of Hydrology 517:187-200. Download  | 
  • Diefenbach, D. R., T. Wagner and G. E. Stauffer. 2014. Setting Objectives for Managing Key Deer. U.S. Department of Interior, Fish and Wildlife Service, Cooperator Science Series FWS/CSS-106-2014,Washington, D.C. Download  | 
  • Deweber, J.T., Y., Tsang, D.M. Krueger, J.B. Whittier, T. Wagner, D.M. Infante, and G. Whelan. 2014. Importance of understanding landscape biases in USGS gage locations: Implications and solutions for managers. Fisheries 39:155-163. Download  | 
  • Lottig, N.R., T. Wagner, E.N. Henry, K. Spence Cheruvelil, K.E. Webster, et al. 2014 Long-Term Citizen-Collected Data Reveal Geographical Patterns and Temporal Trends in Lake Water Clarity. PLoS ONE 9(4): e95769. doi:10.1371/journal.pone.0095769. Download  | 
  • Wagner, T., J.T. Deweber, J. Detar, D. Kristine, and J.A. Sweka. 2014. Spatial and Temporal Dynamics in Brook Trout Density: Implications for Population Monitoring. North American Journal of Fisheries Management 34:258-269. Download  | 
  • Levy, O., B.A. Ball, B. Bond-Lamberty, K.S. Cheruvelil, A.O. Finley, N. Lottig, S.W. Punyasena, J. Xiao, J. Zhou, L.B. Buckley, C.T. Filstrup, T. Keitt, J.R. Kellner, A.K. Knapp, A.D. Richardson, D. Tcheng, M. Toomey, R. Vargas, J.W. Voordeckers, T. Wagner, J.W. Williams. 2014. Approaches to advance scientific understanding of macrosystems ecology. Frontiers in Ecology and the Environment 12:15-23. Download  | 
  • Soranno, P.A., K. Spence Cheruvelil, E. Bissell, M. Tate-Bremigan, J.A. Downing, C.E. Fergus, C. Filstrup, N.R. Lottig, E.N. Henry, E.H. Stanley, C.A. Stow, P.N. Tan, T. Wagner, and K.E. Webster. 2014. Cross-scale interactions: A conceptual framework for understanding multi-scaled cause-effect relationships in macrosystems. Frontiers in Ecology and the Environment 12:65-73. Download  | 
  • Detar, J., D. Kristine, T. Wagner, and T. Greene. 2014. Evaluation of Catch-and-Release Regulations on Brook Trout in Pennsylvania Streams. North American Journal of Fisheries Management 34:49-56. Download  | 
  • Wagner, T., B. J. Irwin, J. R. Bence, and D.B. Hayes. 2013. Detecting temporal trends in freshwater fisheries surveys: statistical power and the important linkages between management questions and monitoring objectives. Fisheries 38:309-319. Download  | 
  • Mollenhauer, R., T. Wagner, M.V. Kepler, J.A. Sweka. 2013. Fall and early winter movement and habitat use of wild brook trout. Transactions of the American Fisheries Society 142:1167-1178. Download  | 
  • Wagner, T., J.T. Deweber, J. Detar, and J.A. Sweka. 2013. Landscape-scale evaluation of asymmetric interactions between brown trout and brook trout using two-species occupancy models. Transactions of the American Fisheries Society 142:353-361. Download  | 
  • Irwin, B.J., T. Wagner, J.R. Bence, M.V. Kepler, W. Liu, and D.B. Hayes. 2013. Estimating spatial and temporal components of variation for fisheries count data using negative binomial mixed models. Transactions of the American Fisheries Society 142:171-183. Download  | 
  • Sweka, J.A., T. Wagner, J. Detar, and D. Kristine. 2012. Combining Field Data with Computer Simulations to Determine a Representative Reach for Brook Trout Assessment. Journal of Fish and Wildlife Management 3:209-222.
  • Rennie, M.D., M.P. Ebener, and T. Wagner. 2012. Can migration mitigate the effects of ecosystem change? Patterns of dispersal, energy acquisition and allocation in Great Lakes lake whitefish (Coregonus clupeaformis). Proceedings of the 10th Annual Coregonid Symposium. Advances in Limnology 63:455-476. Download  | 
  • Wagner, T., D.R. Diefenbach, A.S. Norton, and S.A. Christensen. 2011. Using multilevel models to quantify heterogeneity in resource selection. Journal of Wildlife Management 75:1788-1796. Abstract |  Download  | 
  • Wagner, T., P.A. Soranno, K.E. Webster, and K. Spence Cheruvelil. 2011. Landscape drivers of regional variation in the relationship between total phosphorus and chlorophyll in lakes. Freshwater Biology 56:1811-1824. Abstract | 
  • Soranno, P.A., T. Wagner, S. Martin, L. McLean, L. Novitski,C. Provence, and A. Rober. 2011. Quantifying regional reference conditions for freshwater ecosystem management: A comparison of approaches and future research needs. Lake and Reservoir Management 27:138-148. Abstract | 
  • Wagner, T., and J.A. Sweka. 2011.Evaluation of hypotheses for describing temporal trends in Atlantic salmon parr densities in Northeast U.S. Rivers. North American Journal of Fisheries Management 31:340–351. Abstract | 
  • Soranno, P.A., K. Spence Cheruvelil, K.E. Webster, M.T. Bremigan, T. Wagner, and C.A. Stow. 2010. Freshwater Ecosystem Classification for Landscape-scale Management. BioScience 60:440-454.
  • Wagner, T., and 7 coauthors. 2010. Spatial and temporal dynamics of lake whitefish (Coregonus clupeaformis) health measures: linking individual-based indicators to a management-relevant endpoint. Journal of Great Lakes Research 36:121-134. Abstract | 
  • Miksis-Olds, J. L. and T. Wagner. 2010. Behavioral response of manatees to variations in environmental sound levels. Marine Mammal Science 27: 130–148 Abstract | 
  • Wagner, T., C.S. Vandergoot, and J. Tyson. 2009. Evaluating the Power to Detect Temporal Trends in Fishery-Independent Surveys: A Case Study Based on Gillnets Set in the Ohio Waters of Lake Erie for Walleye. North American Journal of Fisheries Management 29:805-816. Abstract | 
  • Brenden, T. O., T. Wagner, and B.R. Murphy. 2008. Generalized linear mixed modeling as a framework for analyzing proportional size structure index data. North American Journal of Fisheries Management 28:1233-1242. Abstract | 
  • Wagner, T., M.E. Benbow, T.O. Brenden, J. Qi, and R.C. Johnson. 2008. Buruli ulcer disease prevalence in Benin, West Africa: associations with land use/cover and the identification of disease clusters. International Journal of Health Geographics 7:25. Abstract | 
  • Spence Cheruvelil, K., P.A. Soranno, M.T. Bremigan, T. Wagner, and S.L. Martin. 2008. Grouping lakes for water quality assessment and monitoring: the roles of regionalization and spatial scale. Environmental Management 41:425-440. Abstract | 
  • Wagner, T., M.E. Benbow, M. Burns, R.W. Merritt, J. Qi, P.L.C. Small, and R.C. Johnson. 2008. A landscape-based model for predicting Mycobacterium ulcerans infection (Buruli ulcer) presence in Benin, West Africa. EcoHealth 5:69-79. Abstract | 
  • Wagner, T., P.A. Soranno, K. Spence Cheruvelil, B. Renwick, K. Webster, P. Vaux, and R. Abbitt. 2008. Quantifying sample biases of inland lake sampling programs in relation to lake surface area and land use/cover. Environmental Monitoring and Assessment 131-147. Abstract | 
  • Wagner, T., J.R. Bence, M.T. Bremigan, D.B. Hayes, and M.J. Wilberg. 2007. Regional trends in fish mean length at age: components of variance and the power to detect trends. Canadian Journal of Fisheries and Aquatic Sciences 64:968-978.
  • Wagner, T., Bremigan, M. T., Spence Cheruvelil, K., Soranno, P. A., Nate, N. N., and Breck, J. E. 2007. A multilevel modeling approach to assessing regional and local landscape features for lake classification and assessment of fish growth rates. Environmental Monitoring and Assessment 130:437-454.
  • Congleton, J. L., and T. Wagner. 2006. Blood-chemistry indicators of nutritional status in juvenile salmonids. Journal of Fish Biology 69:473-790.
  • Wagner, T. A.K. Jubar, and M.T. Bremigan. 2006. Can habitat alteration and spring angling explain black bass nest distribution and success? Transactions of the American Fisheries Society 135:843-852.
  • Wagner, T., D.B. Hayes, and M.T. Bremigan. 2006. Accounting for multilevel data structures in fisheries data using mixed models. Fisheries 31:180-187.
  • Zabel, R.W., T. Wagner, J.L. Congleton, S.G. Smith, and S.G. Williams. 2005. Survival and selection of migrating salmon from capture-recapture models with individual traits. Ecological Applications 15:1427-1439.
  • Wagner, T., and J.L. Congleton. 2004. Blood-chemistry correlates of nutritional condition, tissue damage, and stress in migrating juvenile chinook salmon (Oncorhynchus tshawytscha). Canadian Journal of Fisheries and Aquatic Sciences 61:1066-1074.
  • Wagner, T., J.L. Congleton, and D.M. Marsh. 2004. Smolt-to-adult return rates of juvenile chinook salmon transported through the Snake-Columbia River hydropower system, USA, in relation to densities of co-transported juvenile steelhead. Fisheries Research 68:259-270.
  • Wagner, T. and C.M. Falter. 2002. Response of an aquatic macrophyte community to fluctuating water levels in an oligotrophic lake. Lake and Reservoir Management 18:52-65.

Current Staff

Federal Staff: 3

Masters Students: 4

Phd Students: 3

Post Docs: 1

University Staff: 3

5 Year Summary

Students graduated: 22

Scientific Publications: 90

Presentations: 129


Contact Us

Pennsylvania Cooperative Fish and Wildlife Research Unit University Park, PA 16802 Phone: (814) 865 - 4511 Fax: (814) 863 - 4710

Unit Leader

Duane Diefenbach
Duane R. Diefenbach

Upon completion of my Ph.D. I worked for the Pennsylvania Game Commission as their biometrician for 7 years. There I began my current research involving grassland sparrows and black bears. Since 1999 I have been a research scientist with the Pennsylvania Unit and enjoy the challenges in integrating research to improve management decisions.


  1. Penn State University Campus Maps

Pennsylvania Cooperative Fish and Wildlife Research Unit Cooperators

  1. Pennsylvania Fish and Boat Commission
  2. Pennsylvania Game Commission
  3. Pennsylvania State University
  4. U.S. Fish and Wildlife Service
  5. U.S. Geological Survey
  6. Wildlife Management Institute