Publications by Year: 2020

Hendrickson, Dean A. 2020. “UT’s Non-Digital Biodiversity Specimens Join the Global Digital Revolution.” UT Biodiversity Center Blog. Publisher's VersionAbstract
The prestigious journal BioScience just released "Natural History Collections: Advancing the Frontiers of Science," a compilation of recent natural history collection-related papers that sheds light on the importance of digitizing and publishing collections data, and the substantial obstacles confronting collections staff working on that. This comes shortly after our own Curator of Entomology, Dr. Alex Wild, posted a description of his own experiences tackling these tasks in his insect collection. All of us curators in the Biodiversity Center know these obstacles all too well, having been laboring on them for decades. As Dr. Wild pointed out, we're making progress despite major limitations, and his collection now being 1% digitized, though perhaps sounding trivial to some, is indeed a major accomplishment. Here, I'll provide a broader perspective, exploring all of our collections combined, since, at long last, I finally can! All of our data from all four primary Biodiversity Center collections are now easily explored anywhere in the world via a single online portal - the international (Global Biodiversity Information Facility).
Hendrickson, Dean A. 2020. “Species in the spotlight: Treasures of the Sierra Madre – Mexico’s little-known native trout diversity.” The status and distribution of freshwater fishes in Mexico, edited by Timothy Lyons, Laura Máiz-Tomé, Marcelo F. Tognelli, Adam Daniels, Clayton Meredith, Robert Bullock, and Ian J. Harrison, 38–41. Cambridge, UK and Albuquerque, New Mexico, USA: IUCN and ABQ BioPark, 38–41. Publisher's VersionAbstract
Few individuals on our planet do not know what trout and salmon are. They are usually recognised as highly palatable, and often colourful species, and most who know them likely visualize cold, beautiful, pristine, free flowing, alpine or forest streams and rivers as their typical habitats. Many will also know of the remarkable migrations taken by some species, moving from their birth locations in rivers to oceans and then returning to their birthplaces to spawn and die. Some may recognise their importance as prized targets of anglers, particularly fly fishers, who spare no expenses to go after these trophies. Many others who might not be so familiar with the characteristics just mentioned may likely recognise species of this family as the tasty, and usually relatively costly fish found frozen or on ice in grocery stores and fish markets, or in cans, or smoked, or served in restaurants. Their flesh, often pink or rosy-coloured, is prized worldwide. There is no doubt that fishes in this family (Salmonidae) are well known in most of the developed and developing countries of the world and that some have become extremely economically and globally important commercial species that support large-scale recreational as well as wild commercial fisheries, and are massively produced by global aquaculture. At the same time many are also imperilled to some degree. Before this project, the Red List database contained 140 species of Salmonids. Here we’ll focus on the genus Oncorhynchus, commonly known as the Pacific salmons and trout, which prior to this project was represented in the Red List by six species. Then, setting aside the many “salmon” of this genus, we’ll focus only on trout, specifically those of a large and diverse lineage, best known for one species, the famous rainbow trout (O. mykiss). Originally known only from California and other Pacific drainages of the U.S., rainbow trout have long been a prized target of anglers, and the species has been bred in captivity for at least 150 years. High demand for it for both sport fisheries, as well as wild and captive protein production, resulted in it now being established on every continent. It has become not only one of the world’s most important recreational fishing species, but also one of the planet’s most widely cultured vertebrates. It is effectively global agriculture’s “fish version” of the chicken, with global aquaculture production of the species in 2014 reaching 812,940 metric tonnes valued at nearly 4 billion US\$ (U.N. Food and Agriculture Organization (FAO) n.d.) That rainbow trout of global fishery and aquaculture fame is known to be one of about 10 closely related subspecies of what is called the “coastal rainbow” branch of the evolutionary tree of the genus. Most of those are from California, but two native Mexican taxa have long been recognised as part of this lineage, O. m. nelsoni (Nelson’s trout – recently reviewed by (Ruiz Campos, 2017)) of the northernmost mountains of Baja California, and O. chrysogaster (the Mexican golden trout – recently covered by multiple contributors (Ruiz-Luna & Garcia De León, 2016). Recent genetic studies (AbadíaCardoso et al., 2015) confirm those relationships and reveal, from specimens collected by the bi-national group of researchers known as Truchas Mexicanas (Hendrickson et al., 2003), that Mexico’s share of the diversity in this lineage is much greater. At least 10 more, still undescribed species of native trout reside in remote, rugged and isolated corners of the Sierra Madre Occidental extending as far south as the high mountains between Mazatlán and Ciudad Durango. Truchas Mexicanas’ fieldwork left no doubt that most share a need for conservation actions to help their often small and fragmented populations persist, and some are critically imperilled (Camarena-Rosales et al., 2006; Hendrickson et al., 2007; Hendrickson & Tomelleri 2019). While their formal descriptions have been delayed for various reasons, recent genetic validation of their distinctiveness, and clear need for recognition of the need for conservation actions on their behalf, led those studying them to petition the IUCN to add them to the Red List while their descriptions are being finalized. That petition was accepted and their assessments were completed as part of this project.
Contreras-MacBeath, Topiltzin, Dean A. Hendrickson, Jairo Arroyave, Norman Mercado Silva, Michael Köck, Omar Domínguez Domínguez, Arcadio Valdés González, et al. 2020. The status and distribution of freshwater fishes in Mexico. Edited by Timothy Lyons, Laura Máiz-Tomé, Marcelo F. Tognelli, Adam Daniels, Clayton Meredith, Robert Bullock, and Ian J. Harrison. 1st ed. Cambridge, UK and Albuquerque, New Mexico, USA: IUCN and ABQ BioPark. Publisher's VersionAbstract
The inland waters of Mexico support a highly diverse group of freshwater fishes with high levels of endemism that occur across a broad range of aquatic habitat types. These aquatic ecosystems provide many direct (e.g., fisheries) and indirect (e.g., agricultural irrigation) benefits to people, and support local livelihoods and economies across Mexico. Freshwater ecosystems are undervalued and receive insufficient funding, political attention and protection. Developing interests and funding for freshwater species conservation is crucial for “bending the curve” to reduce and ultimately reverse freshwater biodiversity declines. Historical disregard for the health and sustainable use of freshwater ecosystems has resulted in alarming rates of loss in the quality and availability of aquatic habitat. This report presents the most recent information on the conservation status and distribution of freshwater fishes in Mexico, and examines the stressors that are driving their declining conservation status. Important conservation actions and considerations are also presented. Five hundred and thirty-six species of freshwater fishes were assessed against the IUCN Red List Categories and Criteria, representing the most comprehensive assessment of freshwater biodiversity in Mexico to date. This assessment seeks to address the insufficient information available on freshwater fish conservation status, which has resulted in their inadequate representation in environmental planning and management. The full data set, including all species distribution maps, is freely available through the IUCN Red List website ( Forty percent of all extant species assessed are threatened with extinction, assuming all Data Deficient species are threatened in the same proportion as those for which enough information was available. The most pervasive threats are related to habitat loss and degradation, which is driven primarily by unsustainable water use and widespread agricultural activity. Excessive extraction of groundwater and diversion of surface water for human consumption, industrial processes, and plantation agriculture has led to widespread flow reductions, reduced water tables, and subsequent drying of aquatic habitat, which is especially prevalent in the arid, endorheic spring systems of northern and central Mexico. Mexico’s vast hydroelectric infrastructure has altered the historical flow regime of many major rivers, blocking natural migration routes and fragmenting subpopulations of native fishes. Agricultural runoff, inadequate wastewater treatment, and industrial discharges have also resulted in increased levels of pollution. A number of non-native fish species have been introduced both intentionally and unintentionally throughout many of Mexico’s natural and artificial surface waters, with profound impacts on native species distribution and abundance. Given the high connectivity of riverine surface waters and underlying aquifers, the impacts of these threats spread rapidly throughout freshwater ecosystems. Future conservation efforts must place greater emphasis on upstream, downstream, and lateral connectivity within water catchments. Systematic conservation planning approaches should be implemented to develop an integrated conservation action plan for freshwater fishes in Mexico, including broad stakeholder participation, environmental monitoring schemes, and the development of protected areas designed to maintain high levels of aquatic connectivity. Another priority is to direct additional research effort towards the high proportion of species assessed as Data Deficient due to insufficient information on their conservation status and distributions. This lack of information presents a significant bottleneck to the effective management and conservation of Mexico’s freshwater habitats and ichthyofauna. From a policy perspective, the information presented in this report will help support the implementation of multilateral environmental agreements in Mexico, guide conservation planning and priority setting at the national and international level, and provide a baseline of conservation success in subsequent assessments of extinction risk. In addition, this new information will help efforts to achieve the targets of the UN Sustainable Development Goals (SDGs), such as: Target 6.6 for protecting and restoring water-related ecosystems; Target 6.5 on implementing integrated water resources management at all levels; Target 15.1 for conservation, restoration and sustainable use of terrestrial and inland freshwater ecosystems and their services; and Target 15.5 focused on urgent and significant action to reduce the degradation of natural habitats, halt the loss of biodiversity and, protect and prevent the extinction of threatened species. The IUCN Red List is one of the most authoritative global standards supporting policy and action to conserve biodiversity. The analysis presented in this report, based on an assessment of species Red List status, will provide new information to help guide conservation actions and development planning to safeguard the diversity of freshwater ichthyofauna in Mexico. Periodic update of IUCN Red List species assessments will enable calculation of a Red List Index of change in freshwater species extinction risk over time, which will inform managers on the conservation effectiveness of any management interventions.
Hendrickson, Dean A., and Adam E. Cohen. 2020. “Fishes of Texas Project (FoTX) Database - Darwin Core.” University of Texas at Austin, Biodiversity Collections accessed via Occurrence dataset. Publisher's VersionAbstract
The Fishes of Texas Project aims to provide reliable occurrences of fishes from Texas and shared drainage basins. Starting with the database of specimens held in the University of Texas' Ichthyology Collection (TNHCi) we added specimen data collected from our study area from all of the museums we could find to create the Fishes of Texas database, which can be queried via our search tools alongside documentation and other resources online ( At the time of this writing the database includes data from 44 specimen holding collections, but the project has grown and will soon include data from non-specimen sources as well. The data, having come from many disparate sources, all with various formatting, were previously difficult to access and analyze as a whole. After extensive compilation, formatting, standardization, georeferencing, and specimen examining the database is a verified and specimen supported dataset for researchers interested in Texas fishes.
Cohen, Adam E., Dean A. Hendrickson, and Gary P Garrett. 2020. “The Value of Specimen Collections for Conserving Biodiversity.” Standing between Life and Extinction, edited by David Propst, Jack Williams, Kevin Bestgen, and Christopher Hoagstrom. University of Chicago Press. Publisher's Version
Hendrickson, Dean A. 2020. “Fish Collection Expands with TPWD.” UT Biodivesity Center News. Publisher's VersionAbstract
A quick overview of 15 years of UT Fish Collection growth and collaborations with Texas Parks and Wildlife by Dean A. Hendrickson, Adam E. Cohen, Gary P. Garrett As stated in the Biodiversity Center’s Collections webpage, the challenges for our collections are to: 1) “document biodiversity,” 2) “understand how biological processes generate and maintain it,” and 3) “communicate those findings and their relevance to a broader community”. Some readers may have seen our recent post about the space issue in UT’s Fish Collection. If not, in a nutshell - we now house 73,047 cataloged jars of preserved fishes containing more than 1.5 million specimens of 871 species, and our continuing growth has us now very close to our facility’s capacity. We thus worry that we will soon be unable to continue addressing challenge 1, and will be lacking up-to-date data needed to continue to evaluate the status of our regional biodiversity (2 and 3).
Curtis, Stephen, Melissa Casarez, and Sarah Robertson. 2020. “The Value of Citizen Scientists: Data Collection for American Eel Using Non-Traditional Field Gear & Social Media”. Publisher's VersionAbstract
American Eel (Anguilla rostrata) is a facultative catadromous species with a unique and complex life history. After hatching, larval eel begin their journey as leptocephalus in the Sargasso Sea and drift on ocean currents along the Atlantic coast, Gulf of Mexico, and Central and South America. They transform into glass eel as they approach shore and begin to develop pigment as they settle in estuaries or move upstream into rivers as elvers. American Eel then spend 3-40+ years in these habitats as yellow eel until they sexually mature into silver eel and return to the Sargasso Sea where they spawn and presumably die. State and federal agencies, multiple universities and numerous citizen science volunteers are working to better understand their movement patterns and recruitment window in Texas. Citizen scientists with coastal chapters of the Texas Master Naturalists (TMN) have taken a lead role in assisting with this effort. Since February of 2018, TMN have established a network of monitoring sites across the mid to upper Texas Coast to sample for juvenile American Eel using eel mops. Eel mops have been deployed for various lengths of time at 29 sites throughout the past two years and checked routinely for glass and elver eel. Volunteers have conducted approximately 250 eel mop checks and provided record of their catch by category (e.g., eel, shrimp, crab, other fish, etc.) based on occurrence or abundance. TMN have documented close to 7,000 individuals across all categories with various species of crab, shrimp, and fish being the most common groups collected. While no glass or elver eel have been collected in an eel mop, TMN have provide valuable data for this project by testing a common gear type that is often used to monitor for American Eel on the Atlantic Coast.
Mayes, Kevin, Stephen Curtis, Grace McCoy, Dean A. Hendrickson, Adam E. Cohen, Melissa Casarez, George Guillen, Jenny Oakley, and Justin Hansen. 2020. “Preliminary Results of American Eel Sampling Efforts in Gulf of Mexico Drainages of Texas”. Publisher's VersionAbstract
American Eel Anguilla rostrata has a unique and complex life history that is fairly well-studied on the eastern coast of the United States, but few studies have been done on Gulf of Mexico drainages. To inform conservation and management decisions, efforts to better understand the population structure, seasonal dynamics, and life history of American Eel are underway. The primary objectives of our efforts are to assess the current and historical distribution and abundance, habitat use, movement patterns, parasite occurrence, diet and population structure of American Eel across all life stages in Gulf of Mexico drainages of Texas. (poster presented at annual meeting of Southern Division of American Fisheries Society, Little Rock, Arkansas, February 2020)