Headshot of John Mohan

John A. Mohan, Ph.D.

Assistant Professor


Marine Science Center 216
Eligible for Student Opportunities



Ph.D. Marine Science
University of Texas at Austin, Marine Science Institute
M.S. Biology
East Carolina University
B.S. Biology - Ecology
Pennsylvania State University


Fish ecology
Fisheries biology


Current research

Testing the effectiveness of a microprocessor-based shark bycatch reduction device (BRD) in the laboratory, recreational fisheries and longline fisheries

Enhancing shark and ray conservation in the Gulf of Mexico through natural tracers in vertebrae

Investigating Saco River striped bass life history using acoustic telemetry, eDNA, and natural chemical tracers in scales and otoliths

Selected publications

*Brodbeck, B.E., K. Lyons, N. Miller, J.A. Mohan. 2023. Sex influences elemental variation in the mineralized vertebrae cartilage of round stingray (Urobatis halleri). Marine Biology 170:117. DOI:

Gibson-Banks, M. Streich, J.M. Drymon, S.B. Scyphers, J.A. Mohan, R.J.D. Wells, A. Binstock, T.M. Richards, C. White, N.M. Whitney, G. Stunz. 2023. Talk is cheap: direct evidence of conservation-based changes in angler behavior. Conservation Science and Practice e13001. DOI:

*Binstock, A., T.M. Richards, K. Gibson-Banks, M. Streich, G. Stunz, C. White, N. Whitney, J.M. Drymon, R.J.D. Wells, J.A. Mohan. 2023. Variable post-release mortality in four common shark species captured in Texas shore-based recreational fisheries. PLoS ONE 18(2): e0281441. DOI:

*LaFreniere, B.R., O. Sosa-Nishizaki, S.Z. Herzka, O. Snodgrass, H. Dewar, N. Miller, R.J.D. Wells,   J.A. Mohan. 2023. Vertebral chemistry distinguishes nursery habitats of juvenile shortfin mako (Isurus oxyrinchus) in the eastern North Pacific Ocean. Marine and Coastal Fisheries

Mohan, J.A., A.E. Romo Curiel, S. Herzka, R.J.D. Wells, N.R. Miller, O. Sosa Nishizaki, E. Garcia Rodriguez. 2023. Inferring habitat use of Pacific White Shark using vertebral chemistry. Frontiers in Marine Science. DOI: 10.3389/fmars.2022.1082219

Mohan, J., H. Dewar, O.E. Snodgrass, N.R. Miller, Y. Tanaka, S. Ohshimo, J.R. Rooker, R.J.D. Wells. 2022. Otolith geochemistry reflects life histories of Pacific bluefin tuna. PLoS ONE 17(10): e0275899. DOI: 10.1371/journal.pone.0275899

Andrzejaczek, S., T. Lucas, M. Goodman, N. Hussey… J. Mohan, et al. 2022. Diving into the vertical dimension of elasmobranch movement ecology. Science Advances. DOI: 10.1126/sciadv.abo1754

Lueders-Dumont, J.A., A.G. Forden, E.R. Kast, J.A. Mohan, B.D. Walther, D.M. Sigman, B.B. Ward. 2022. Controls on the nitrogen isotopic composition of fish otolith organic matter: lessons from a controlled diet switch experiment. Geochimica et Cosmochimica Acta. DOI:

Livernois, M.C., J.A. Mohan, T. C. TinHan, T. M. Richards, B. Falterman, N.R. Miller, R.J.D.Wells. 2021. Ontogenetic patterns of elemental tracers in the vertebrae cartilage of coastal and oceanic sharks. Frontiers in Marine Science. DOI: 10.3389/fmars.2021.704134

Rooker, J.R., R.J.D. Wells, B.A. Block, H. Liu, H. Baumann, W.C. Chiang, M. Sluis-Zapp, N.R. Miller, J.A. Mohan, S. Ohshimo, Y. Tanaka, M.A. Dance, H. Dewar, O.E. Snodgrass, J.C Shiao. 2021. Natal origin and age-specific egress of Pacific bluefin tuna from coastal nurseries revealed with geochemical markers. Scientific Reports DOI:

Mohan, J.A., E. Jones, J. Hendon, B. Falterman, K. Boswell, E. Hoffmayer, R.J.D. Wells. 2020. Capture stress and post-release mortality of blacktip sharks in recreational charter fisheries of the Gulf of Mexico. Conservation Physiology DOI:10.1093/conphys/coaa041

Matich P., R. Nowicki, J. Davis, J.A. Mohan, J.D. Plumlee, B. Strickland, T. Tinhan, R.J.D. Wells, M. Fisher. 2020. Does freshwater refuge shape size structure of an estuarine predator (Carcharhinus leucas) in the northwestern Gulf of Mexico? Marine and Freshwater Research DOI:

Boswell, K.M., M. D’Elia, M.W. Johnston, J.A. Mohan, J.D. Warren, R.J.D. Wells, T.T. Sutton. 2020. Oceanographic structure and light levels drive patterns of mesopelagic scattering layers in a low-latitude oceanic system. Frontiers in Marine Science DOI: 10.3389/fmars.2020.00051

Wells, R.J.D., J.A. Mohan, H. Dewar, J.R. Rooker, Y. Tanaka, O.E. Snodgrass, S. Kohin, N.R. Miller, S. Ohshimo. 2020. Natal origin of Pacific bluefin tuna from the California Current Large Marine Ecosystem. Biology Letters 16:20190878. DOI: 10.1098/rsbl.2019.0878

Mohan, J.A., N.R. Miller, S.S. Herzka, O. Sosa-Nishizaki, S. Kohin, H. Dewar, M. Kinney, O. Snodgrass, R.J.D. Wells. 2018. Elements of time and place: manganese and barium in shark vertebrae reflect age and upwelling histories. Proceedings of the Royal Society – Biology 285:20181760. DOI: 10.1098/rspb.2018.1760

R.J.D. Wells, T.C TinHan, M.A. Dance, J.M. Drymon, B. Falterman, M.J. Ajemian G.W. Stunz, J.A. Mohan, E.R. Hoffmayer, W.B. Driggers III, J.A. McKinney. 2018. Movement, behavior and habitat use of a marine apex predator, the scalloped hammerhead. Frontiers in Marine Science 5:321. DOI: 10.3389/fmars.2018.00321

TinHan, T.C., J.A. Mohan, M. Dumesnil, B. DeAngelis, R.J.D. Wells. 2018. Linking habitat use and trophic ecology of spotted seatrout (Cynoscion nebulosus) on a restored oyster reef in a subtropical estuary. Estuaries and Coasts 41:1793-1805. DOI: 10.1007/s12237-018-0391-x

Plumlee, J.D., K.M. Dance, P. Matich, J.A. Mohan, T.M. Richards, T.C. TinHan, R.J.D. Wells. 2018. Community structure of elasmobranchs in estuaries along the northwest Gulf of Mexico. Estuarine, Coastal and Shelf Science 204:103-113. DOI: 10.1016/j.ecss.2018.02.023

Mohan, J.A. and B.D. Walther. 2018. Integrating multiple natural tags to examine migration patterns and resource partitioning across a subtropical estuarine gradient. Estuaries and Coasts 41:1806-1820. DOI: 10.1007/s12237-018-0385-8

Mohan, J.A., T. TinHan, N.R. Miller, R.J.D. Wells. 2017. Effects of sample cleaning and storage on the elemental composition of shark vertebrae. Rapid Communications in Mass Spectrometry 31:2073-2080. DOI: 10.1002/rcm.7998

Chagaris, D., S. Binion, A. Bodanoff, K. Dahl, J. Granneman, H. Harris, J. Mohan, M. Rudd, M. Swenarton, R. Ahrens, M. Allen, J. Morris, W. Patterson. 2017. An ecosystem-based approach to evaluating impacts and management of invasive lionfish. Fisheries 42:421-431. DOI: 10.1080/03632415.2017.1340273

Matich, P., J.A. Mohan, J.D. Plumlee, T. Tinhan, R.J.D. Wells, M. Fisher. 2017. Factors shaping the co-occurrence of two juvenile shark species along the Texas Gulf Coast. Marine Biology 164:141. DOI: 10.1007/s00227-017-3173-2

Mohan, J.A., T.T. Sutton, A.B. Cook, K. Boswell, R.J.D. Wells. 2017. Influence of oceanographic conditions on abundance and distribution of post-larval and juvenile carangid fishes in the northern Gulf of Mexico. Fisheries Oceanography 26: 526-541. DOI: 10.1111/fog.12214

Mohan, J.A., and B.D. Walther. 2016. Out of breath and hungry: natural tags reveal trophic resilience of Atlantic croaker to hypoxia exposure. Marine Ecology Progress Series 560:207-221. DOI: 10.3354/meps11934

Mohan, S.D., J.A. Mohan, T.L. Connelly, B.D. Walther, J.W. McClelland. 2016. Fatty acid biomarkers and tissue-specific turnover: validation from a controlled feeding study in juvenile Atlantic croaker Micropogonias undulatus. Journal of Fish Biology 84:2004-2023. DOI: 10.1111/jfb.13099

Mohan, J.A., S.D. Smith, T.L. Connelly, E.T. Attwood, J. McClelland, S.Z. Herzka, B.D. Walther. 2016. Tissue-specific isotope turnover and discrimination factors are affected by diet quality and lipid content in an omnivorous consumer. Journal of Experimental Marine Biology and Ecology 479:35-45. DOI: 10.1016/j.jembe.2016.03.002

Díaz-Gil, C., M. Palmer, I.A. Catalán, J. Alós, L. Fuiman, E. García, M. del Mar Gil, A. Grau, A. Kang, R.H. Maneja, J. Mohan, B. Morro, J.J. Schaffler, L. Buttay, B. Tolosa, B. Morales-Nin. 2015. Otolith fluctuating asymmetry: A misconception of its biological relevance? ICES Journal of Marine Science 72:2079-2089. DOI: 10.1093/icesjms/fsv067

Mohan, J.A., and B.D. Walther. 2015. Spatiotemporal variation of trace elements and stable isotopes in subtropical estuaries: II. Regional, local, and seasonal salinity-element relationships. Estuaries and Coasts 38:769-781. DOI: 10.1007/s12237-014-9876-4

Mohan, J.A., N.M Halden, and R.A. Rulifson. 2015. Habitat use of juvenile striped bass Morone saxatilis (Actinopterygii: Moronidae) in rivers spanning a salinity gradient across a shallow wind-driven estuary. Environmental Biology of Fishes 98:1105-1116. DOI: 10.1007/s10641-014-0344-6.

Limburg, K.E., B.D. Walther, Z. Lu, G. Jackman, J. Mohan, Y. Walther, A. Nissling, P.K. Weber, and A.K. Schmitt. 2015. In search of the dead zone: use of otoliths for tracking fish exposure to hypoxia. Journal of Marine Systems 141:167-178. DOI: 10.1016/j.jmarsys.2014.02.014

Mohan, J.A., M.S. Rahman, P. Thomas, B.D. Walther. 2014. Influence of constant and periodic experimental hypoxic stress on Atlantic croaker otolith chemistry. Aquatic Biology 20:1-11. DOI: 10.3354/ab00542

Mohan, J.A., R.A. Rulifson, D.R. Corbett, and N.M. Halden. 2012. Validation of oligohaline elemental otolith signatures of striped bass by use of in situ caging experiments and water chemistry. Marine and Coastal Fisheries: Dynamics, Management, and Ecosystem Science 4:57-70. DOI: 10.1080/19425120.2012.656533

Other scholarly activity

Past-president, Estuaries Section of the American Fisheries Society

Funded grants

Save Our Seas Foundation - Small Grants (PI) Conservation implications of biomineralization patterns in shark vertebrae cartilage.

NOAA Cooperative Research Program (co-PI) Life history and age validation of blacktip sharks (Carcharhinus limbatus) in the Gulf of Mexico with implications for stock assessment models

NOAA Cooperative Research Program (PI) Post-release mortality and behavior of sharks in shore-based recreational fisheries using citizen scientists and low-cost tags

Research interests

Fish ecology, life history, population connectivity, movement ecology, trophic ecology, geochemistry of biominerals, environmental hypoxia stress, recreational fishing stress and post-release mortality