About

Don Orth is a faculty member at Virginia Tech in the Department of Fish and Wildlife Conservation. The page indicates he is a Professor, but does not provide specific details about his research focus, background, or key contributions. The available information is limited to his title and contact details, with no additional biographical or professional summary provided.

Research topics

• Biology
• Fishery
• Geography
• Environmental science
• Ecology
• Linguistics

Selected publications

• Management strategy evaluation to assess trade-offs associated with invasive Blue Catfish fisheries and predation impacts

  Marine and Coastal Fisheries · 2025-01-01 · 1 citations

  articleOpen accessSenior author

  ABSTRACT Objective Many species are intentionally introduced beyond their native range to provide benefits to humans (e.g., food, recreation, or biocontrol). However, introduced species can become invasive and can harm native species, prompting resource managers to explore options to simultaneously conserve native biota and enhance fishing opportunities. Management of Chesapeake Bay Blue Catfish Ictalurus furcatus is complicated because the species supports a renowned trophy fishery and commercial and recreational harvest but also negatively affects native species. Consequently, there is uncertainty and disagreement on how to balance trade-offs associated with varying stakeholder interests. Methods We used a management strategy evaluation to project Blue Catfish population dynamics into the future under different fishery policies to understand whether fishery yield, trophy fishing opportunities, and predation on the economically and ecologically important blue crab Callinectes sapidus could be optimized in the James River, a Chesapeake Bay subestuary. Results Simulated population trajectories indicated that objectives related to maintaining fisheries and conserving prey populations were in conflict. Policies that increased the yield and abundance of trophy-size Blue Catfish (≥100 cm total length) generally increased predation on the blue crab, which supports a valuable fishery. Intense harvest of smaller length-classes and protection of larger Blue Catfish yielded outcomes in which trophy fish abundance increased and blue crab predation declined compared to baseline conditions. However, these outcomes were generally associated with lower Blue Catfish yields after 25 years. There were zero scenarios in which the fishery yield increased and blue crab predation decreased after 25 years. Policies limiting the harvest of small Blue Catfish resulted in large population abundances, suggesting that reducing the abundance of small fish could be important for reducing impacts on native species. Conclusions This study supports the importance of management planning to develop objectives and performance measures based on an improved understanding of trade-offs associated with harvest management for a nonnative fish with economic value.

  PublisherDOI

• Migratory Ecology of Pseudoplatystoma fasciatum in the Amazon Basin Revealed by Otolith Microchemistry

  Diversity · 2024-06-29

  articleOpen access

  Fish migrate for varied reasons, including to avoid predators and to access feeding, spawning, and nursery habitats, behaviors that enhance their survival and reproductive rates. However, the migratory ecology of many important fishes, especially those in river–floodplain ecosystems, remains poorly understood. One fish of the Amazon Basin whose migratory behavior is poorly understood is the catfish Pseudoplatystoma fasciatum. Here, we used otolith elemental microchemistry to characterize the migration ecology of P. fasciatum in the Amazon Basin. The main research questions of this study were: (1) does P. fasciatum move between waters with different Sr isotopic signatures (87Sr/86Sr) and chemical compositions? (2) What distance do they migrate? (3) Is the migration of P. fasciatum related to age? And (4) does P. fasciatum migrate mainly upstream, downstream, or in both directions? We assessed whether P. fasciatum migrates between waters with different 87Sr/86Sr values, comparing the Sr isotopic signature of otolith transects of each individual with the range of Sr isotopic signatures within the respective rivers. We found that 34% of the 71 fish analyzed migrated between rivers with different Sr isotopic signatures and 66% did not. The mean migration distance migrated was 126 km, with most specimens migrating between 72 and 237 km. Apparently, no fish of age one or age six or older migrated. All fish that migrated were between two and five years of age, with 20% of the specimens that migrated being two years old, 40% three years old, 30% four years old, and 20% five years old. Sixty-six percent of all individuals that migrated between rivers with different Sr signatures did so bidirectionally, while 33% moved unidirectionally. According to our definition of homing behavior in which fish migrated back to the same river where they were born, 41% of all fish that migrated displayed apparent homing behavior. Our findings provide insights into the migratory ecology of P. fasciatum, corroborating and refining knowledge reported in the literature. Our results on the migratory ecology of P. fasciatum have implications for sustainable fisheries conservation and management: conserving P. fasciatum requires habitat maintenance and suitable fishing practices in spawning and nursery habitats, and managers must consider large geographic areas for effective fishery management and conservation.

  PublisherOA PDFDOI

• Conservation Genetics of Clinch Dace Chrosomus sp. cf. saylori

  Fishes · 2023-07-13

  articleOpen access

  Clinch Dace (Chrosomus sp. cf. saylori) is a newly recognized and yet-undescribed species of minnow with a restricted and fragmented distribution in the upper Tennessee River basin in southwestern Virginia, USA. We collected Clinch Dace from seven streams and observed variations at nine selectively neutral microsatellite DNA loci to infer population genetic processes and identify units for conservation management. Bayesian cluster analysis showed that three of the seven surveyed populations were genetically distinct, while the other four populations showed signs of recent admixture. Estimated effective population sizes and m-ratios were low within most populations, suggesting loss of alleles due to recent genetic drift. Positive FIS values, high average individual inbreeding coefficients, and high degrees of inferred relatedness among individuals suggested that inbreeding is taking place in some populations. FST values were high, and analysis of molecular variance indicated genetic divergence among populations. These indicators suggest that Clinch Dace populations are subject to the genetic processes that are characteristic of small and isolated populations.

  PublisherOA PDFDOI

• Predatory impacts of invasive Blue Catfish in an Atlantic coast estuary

  Marine and Coastal Fisheries · 2023-10-01 · 13 citations

  articleOpen accessSenior author

  Abstract Objective Predatory invasive fishes may consume species of management interest and alter food webs. Blue Catfish Ictalurus furcatus is a large-bodied, salinity-tolerant species that exhibits broad diet breadth and preys on species of both conservation concern and fisheries management interest. To better understand the ecological consequences of the establishment of Blue Catfish fisheries, estimates of predatory impacts are needed. Methods Using a Monte Carlo simulation, we integrated abundance estimates, diet information, and consumption-to-biomass ratios to estimate population-level Blue Catfish predation for a large Chesapeake Bay tributary along the mid-Atlantic coast of the United States, the James River. Result Population-level annual predation estimates by Blue Catfish exceeded 100 metric tons for several species or taxa of interest, including an estimated 400.7 metric tons (95% CI = 272.6–613.2) of blue crab Callinectes sapidus. Prey species abundances were unknown and thus limited opportunities to evaluate prey population responses. For instance, effects of Blue Catfish on blue crab populations remain unknown without tributary-specific estimates of blue crab abundance, but comparisons to landings data suggests that Blue Catfish predation on blue crab in the James River may be low compared with harvest. Conclusion Estimation of Blue Catfish predatory effects may inform development of management goals and objectives that balance diverse stakeholder interests. This work provides beneficial information to assess trade-offs of Blue Catfish fisheries and their effects on coastal aquatic resources.

  PublisherOA PDFDOI

• A Synthesis of the Ecology and Conservation of Pseudoplatystoma Catfishes in the Neotropics

  Fishes · 2023-06-07 · 5 citations

  articleOpen access

  Species of the genus Pseudoplatystoma, the long-whiskered catfishes, are important in commercial and recreational fisheries in South America, and some species have become key to regional aquaculture. Some species of the genus are under pressure due to overfishing and the negative impacts of dams. Six questions are asked in this review: (i) What species are in the genus, and where are they distributed? (ii) What are the life histories and ecologies of Pseudoplatystoma species? (iii) What are the patterns of somatic growth for these species? (iv) What is known about the biomass, production, and population dynamics of Pseudoplatystoma? (v) What is the geographic distribution of genetic variation within Pseudoplatystoma species? (vi) What are the threats to the conservation of these species? The taxonomy of the genus currently includes eight species, respectively, distributed over the Orinoco, Amazon, Paraná, and São Francisco basins. Pseudoplatystoma catfishes typically exhibit longitudinal migrations for reproduction and lateral migration for feeding, but these patterns may vary among populations. The size of the first maturation of these catfishes varies between 57 cm to 82 cm in total length. Five of the eight species spawn during the rising water season. Pseudoplatystoma species can grow to about 130 cm in total length and 100 Kg in weight and live until 30 years of age, depending upon the species. Biomass production and population dynamics of these catfishes have not yet been fully described. Their life-history characteristics indicate that they are periodic strategists with associated population recruitment dynamics. Population genetic patterning varies among Pseudoplatystoma species, with some degree of homing behavior and genetic differentiation among populations, indicating the need for management by applying the Management Unit and perhaps Evolutionary Significant Unit concepts. The main threats to the persistence of these catfishes are overfishing and alterations in and obstruction of river flow due to the construction of hydropower dams. After synthesizing existing information on species of the genus Pseudoplatystoma, we offer suggestions for future research to fill critical gaps in the knowledge of this group.

  PublisherOA PDFDOI

• My Life in Fish: One Scientist's Journey Gary D. Grossman. Illustrated by Ryan Tavarez. Published by Impspired Press. 2023. US$17.99 (Paperback).

  Fisheries · 2023-11-27

  articleOpen access1st authorCorresponding

  FisheriesEarly View Book Review My Life in Fish: One Scientist's Journey Gary D. Grossman. Illustrated by Ryan Tavarez. Published by Impspired Press. 2023. US$17.99 (Paperback). Donald J. Orth, Donald J. Orth [email protected] orcid.org/0000-0002-9236-0147 Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USASearch for more papers by this author Donald J. Orth, Donald J. Orth [email protected] orcid.org/0000-0002-9236-0147 Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USASearch for more papers by this author First published: 27 November 2023 https://doi.org/10.1002/fsh.11023Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Early ViewOnline Version of Record before inclusion in an issue RelatedInformation

  PublisherOA PDFDOI

• Fish, Fishing, and Conservation

  2023 · 18 citations

  1st authorCorresponding
  • Fishery
  • Geography
  • Biology

  <br><i><b>Fish, Fishing, and Conservation</i></b> is a 389-page, peer-reviewed open textbook intended for undergraduate students who are exploring majors in Fish & Wildlife. It is also relevant to a general audience or for use in courses which explore social and ethical aspects of fish, fishing and conservation. People, places, and approaches to fishing are as varied as the diverse fish fauna that exist on the planet. As conservation planners recognize the value of substantial engagement of stakeholders in decision making and ineffectiveness of rigid top-down management approaches, <i>Fish, Fishing, and Conservation</i> asserts that all peoples must play a role in conservation. Through case studies, engaging narrative and graphics, and exercises, the text explores major motivations for fishing and non-fishing related values, responsible fisheries practices, the rights of all people to decide how to manage and conserve fish, their habitats, and how they are utilized in the context of overfishing as a pressing global problem for which appropriate solutions are not easily found nor implemented. Introductory chapters examine fish, fishing, and why fish matter and examine the role of values in driving conservation initiatives. Fish and their unique sensory capabilities are described along with a review of recent studies to examine issues of pain, sentience, and learning in fishes living in a foreign, underwater world. The text incorporates these new findings in conservation and management leading readers to evaluate and adopt suitable approaches to ethical reasoning which consider the welfare needs of wild and cultured fishes. Later chapters focus on the role of gender in fishing, conservation organizations, recreational fishing, and a focus on specific fisheries that reveal the principles of conservation and management as they play out in major controversies. Additionally, the textbook contains audio recordings of professional profiles by Virginia Tech students. These are linked at the beginning of each end-of-chapter Professional Profile. <br><a href="https://open.spotify.com/show/06SnqAigflPXUgGNIHZxAX?si=Sljj3q9NRyOcclbmEE3npA ">Audio recordings are also available on Spotify</a>. <b>Are you reviewing or adopting this book for a course?</b> <br>Please help us understand your use by filling out <b><a href="https://bit.ly/fishandconservation_interest">this form</a></b>. <b>How to access this book</b> <br>The main landing page for this book is <a href="https://doi.org/10.21061/fishandconservation">https://doi.org/10.21061/fishandconservation</a>. <br>The text is available in multiple formats, including PDF, ePub, and <a href="https://pressbooks.lib.vt.edu/fishandconservation">online Pressbooks version</a>. <br><a href="https://www.amazon.com/dp/1957213280">Click here to order a print copy</a>. <b>Teaching resources</b> <br>Additional teaching resources including a sample syllabus, course schedule, and selected assignments related to this book are available at <a href="http://hdl.handle.net/10919/115425">http://hdl.handle.net/10919/115425</a>. Individuals who wish to share their materials relevant to teaching in this subject area are encouraged to join and share their openly-licensed resources via the <a href="https://oercommons.org/groups/fish-fishing-and-conservation-instructor-group/14049">Fish, Fishing, and Conservation instructor group in OERCommons</a>. <b>ISBNs</b> <br>ISBN (PDF): 978-1-957213-27-9 <br>ISBN (print): 978-1-957213-28-6 <br><a href="https://www.amazon.com/dp/1957213280">Click here to order a print copy</a> <br>ISBN (Pressbooks): 978-1-957213-31-6 <br><a href="https://pressbooks.lib.vt.edu/fishandconservation">Online (Pressbooks)</a> <br>ISBN (EPUB): 978-1-957213-29-3 <b>Table of contents</b> 1. Fish, Fishing, and Why They Matter 2. Values Drive Fish Conservation 3. Sensory Capabilities of Fish 4. Ethical Reasoning and Conservation Planning 5. Pain, Sentience, and Animal Welfare 6. Public Aquariums and Their Role in Education, Science, and Conservation 7. Gender and Fishing 8. Angling and Conservation of Living Fishy Dinosaurs 9. Fly Fishing’s Legacy for Conservation 10. Recreational Fishing and Keep Fish Wet 11. Integrating Fishers in the Management of Arapaima 12. Conserving Tunas: The Most Commercially Valuable Fish on Earth 13. Groupers and Spawning Aggregations 14. Menhaden and Forage Fish Management 15. Takeaways for Successful Fish Conservation <b>Suggested citation</b> <br>Orth, Donald (2023). <i>Fish, Fishing, and Conservation</i>. Blacksburg: Virginia Tech Department of Fish and Wildlife Conservation. <a href="https://doi.org/10.21061/fishandconservation">https://doi.org/10.21061/fishandconservation</a>. Licensed with <a href="https://creativecommons.org/licenses/by/4.0">CC BY 4.0</a>. <b>About the author</b> <br>Donald J. Orth is the Thomas H. Jones Professor in the Department of Fish and Wildlife Conservation at Virginia Polytechnic Institute and State University. He has taught the following courses: Ichthyology, Stream Habitat Management, Fisheries Management, Fish Population Dynamics, Fish, Fishing, and Conservation, and First-Year Experience in Natural Resources. His principal interests are in population and community ecology, stream fish ecology, regulated rivers, instream flow and stream habitat assessment, fisheries management, and fish population dynamics. He has guided numerous undergraduate research projects and advised 33 graduate students during his career. Don attended Eastern Illinois University (BS) and Oklahoma State University (MS and PhD). He is a Life Member of the American Fisheries Society and a Certified Fisheries Professional. He is also a Fellow of the American Fisheries Society, the American Institute of Fisheries Research Biologists, and the Virginia Natural Resources Leadership Institute. Don has published more than 150 primary papers and 50 technical reports on fish, fisheries, and riverine management. Much of his research was also communicated with a general audience in over 180 popular articles. He has received numerous awards for his teaching and contributions to conservation and public outreach. Most recently, the Virginia Chapter of the American Fisheries Society awarded him the Eugene W. Surber Award for years of significant contributions to the field of fisheries science. <b>Selected acknowledgments</b> <br>Publication of this work was made possible in part by grants from <a href="https://vivalib.org">VIVA</a>, the Virtual Library of Virginia, and the University Libraries at Virginia Tech through its <a href="https://guides.lib.vt.edu/oer">Open Education Initiative</a>, which provides development assistance and financial support to Virginia Tech faculty who wish to use, create, or adapt openly licensed teaching materials to support student learning. The University Libraries also contributed faculty and staff support. Donald Orth’s contributions were supported in part by the U.S. Department of Agriculture through the National Institute of Food and Agriculture Program and Virginia Tech Polytechnic Institute and State University. Additional funding support was provided by the Thomas H. Jones Endowment. <b><a href="https://bit.ly/fishandconservation_errors">View errata</a> <br><a href="https://bit.ly/fishandconservation_error">Report an error</a></b> <b>Accessibility statement</b> <br>Virginia Tech is committed to making its publications accessible in accordance with the Americans with Disabilities Act of 1990. The Open Education Initiative is committed to continuous improvement regarding accessibility. The text, images, and links in the PDF versions of this text are tagged structurally and include alternative text, which allows for machine readability. Audio recordings of each profile in fish conservation are available as mp3 files via Spotify and Pressbooks. Please contact openeducation@vt.edu if you are a person with a disability and have suggestions to make this book more accessible. <b>Cover art</b>: Nora Ligus <br><b>Cover design</b>: Kindred Grey

  PublisherOA PDFDOI

• A size‐based stock assessment model for invasive blue catfish in a Chesapeake Bay sub‐estuary during 2001–2016

  Fisheries Management and Ecology · 2022-11-07 · 9 citations

  articleOpen accessSenior author

  Abstract Stock assessment modeling provides a means to estimate the population dynamics of invasive fishes and may do so despite data limitations. Blue catfish ( Ictalurus furcatus ) were introduced to the Chesapeake Bay watershed to support recreational fisheries but also consume species of conservation need and economic importance. To assess management tradeoffs, managers need to understand the current status of the population and anticipate future population abundance and trends. A Bayesian size‐based stock assessment model was used to estimate blue catfish abundance, fishing mortality, and size structure over time (2001–2016) in the tidal James River. The model estimated population size increases until around 2006, with declines in total abundance after 2011 and large blue catfish (≥80 cm total length) after 2001. These first estimates of blue catfish population dynamics in the Chesapeake Bay region provide inputs for projection models to evaluate prospective management actions and identify monitoring needs.

  PublisherOA PDFDOI

• Estimates of Food Consumption Rates for Invasive Blue Catfish

  Transactions of the American Fisheries Society · 2021-04-28 · 9 citations

  articleOpen accessSenior author

  Abstract As a prolific invasive species, Blue Catfish Ictalurus furcatus threaten native organisms in numerous estuarine and tidal freshwaters along the Atlantic coast of the United States. However, no published estimates of consumption rates are available for Blue Catfish in the scientific literature. This information is critical for development of bioenergetics models or estimation of population‐level impacts on native species. Using a combination of field and laboratory studies, we provide the first estimates of daily ration, maximum daily ration, and consumption to biomass ratios for Blue Catfish populations. Ad libitum feeding trials conducted in our laboratory reveal that maximum daily ration in Blue Catfish varies by prey type, temperature, and fish size, with maximal feeding occurring in medium‐sized Blue Catfish (500–600 mm total length) and at temperatures ≥15°C. Furthermore, estimates of daily ration were higher for fish prey (Gizzard Shad Dorosoma cepedianum ) than for crustacean prey (blue crab Callinectes sapidus ). Diel feeding chronologies based on field‐collected diet samples from 1,226 Blue Catfish demonstrated river‐specific variability in daily ration and maximum daily ration. Blue Catfish daily ration ranged between 2.27% and 5.22% bodyweight per 24 h, while maximum daily ration ranges between 8.56% and 9.37% bodyweight per 24 h. Estimates of consumption to biomass ratios varied by river and Blue Catfish size groupings but range between 2.42 and 3.39, which is similar to other benthic omnivores. This research will inform the assessment of predatory impacts of invasive Blue Catfish in the Chesapeake Bay and beyond as it will enable researchers to estimate predatory impacts through the coupling of population models, food habit information, and consumption rate information (current study).

  PublisherOA PDFDOI

• Growth Dynamics of Invasive Blue Catfish in Four Subestuaries of the Chesapeake Bay, USA

  North American Journal of Fisheries Management · 2020 · 14 citations

  Senior authorCorresponding
  • Fishery
  • Environmental science
  • Ecology

  Abstract Biological invasions occur as a multistage process, and life history traits can change during the invasion process. Blue Catfish Ictalurus furcatus were introduced in three Virginia tidal tributaries of the Chesapeake Bay during the 1970s and 1980s but have expanded their range to almost all large tributaries of the bay. An understanding of the species’ growth is important for evaluating impacts on other resident species and population dynamics. Virginia Blue Catfish exhibited wide variability in individual growth, prompting the testing of six alternative hypotheses (similar growth across space and time as well as variable growth by river system, sampling year, cohort, and both river system and time) on its growth dynamics within four Virginia tidal rivers (James, Mattaponi, Pamunkey, and Rappahannock rivers) over the period 2002–2016. Blue Catfish growth in Virginia was best explained by a model considering cohort and river as random effects. The Rappahannock River was the first in Virginia to receive Blue Catfish; growth was slower in this river than in the other systems during the observation period. Growth rates declined for all ages examined in the James, Mattaponi, and Pamunkey rivers but only for ages 7, 10, and 13 in the Rappahannock River. We did not generally observe synchronous growth responses among rivers, supporting that finer-scale factors may be influencing growth rates. This work suggests that the growth rates of nonnative species may decline over time and that comparisons of nonnative growth may be most useful when variability over space and time is considered.

  PublisherOA PDFDOI

Frequent coauthors

• Joseph D. Schmitt

  United States Geological Survey

  30 shared

• Corbin D. Hilling

  24 shared

• Ryan A. McManamay

  Baylor University

  16 shared

• Eric M. Hallerman

  Virginia Tech

  11 shared

• Fabrice Duponchelle

  Institut de Recherche pour le Développement

  10 shared

• Rebecca Beamish

  Starship Children's Health

  9 shared

• C. Andrew Dolloff

  Virginia Tech

  9 shared

• Leandro Castello

  Virginia Tech

  8 shared

Labs

• Don Orth LabPI