Cohen, Adam E., Melissa J. Casarez, and Ryan Rash. 2018. “Fish Collection Finishes Survey of the Little River.” University of Texas Austin Biodiversity Blog. Publisher's VersionAbstract
Staff from the Biodiversity Center’s fish collection (home of the Fishes of Texas Project) recently teamed up with Texas Parks and Wildlife Department’s River Studies Program (TPWD) to conduct a fish survey of the Little River in Central Texas. The Little River is little in name only and covers nearly 3% of the state of Texas, from Eastland southeast to Hearne, and includes well-known tributaries such as the Leon, San Gabriel, and the Lampasas Rivers. We collected fish at 63 sites from March to July of this year. All fish have been identified, counted, measured, and cataloged and are soon to be shelved and made available to the world’s taxonomists, ecologists, and researchers in general. We collected 52 species altogether, including 12 non-native species (see full list below). This survey is part of a larger on-going project which targets undersampled watersheds throughout the state, filling in critical research needs to aid in conservation efforts of native species and restoration of the rivers they inhabit. Other participants in this survey include Austin Youth River Watch, a non-profit focusing on environmental education of underserved youth, and Dr. Michael Collins of the Gault School of Archaeological Research, who provided access to Buttermilk Creek, a perennially flowing creek that runs through the Gault archeological site.
Birdsong, Timothy W., Daniel C. Dauwalter, Gary P. Garrett, Benjamin J. Labay, Megan G. Bean, James Broska, Jessica Graham, et al. 2018. “Native Fish Conservation Areas of the Southwestern USA: Facilitating Landscape-Scale Conservation of Aquatic Habitats and Freshwater Fishes..” Wildlife Management Institute, 147.Abstract
Native Fish Conservation Areas of the southwestern USA consist of springs, ciénegas, creeks, rivers, and associated watersheds uniquely valued in preservation of freshwater fish diversity. These freshwater systems were identified through a spatial prioritization approach that identifies areas critically important to the long-term persistence of focal fish species. Through a shared mission of collaborative stewardship, conservation partnerships have formed among non-governmental organizations, universities, and state and federal agencies to plan and deliver actions to restore and preserve native freshwater fishes and aquatic habitats within the Native Fish Conservation Areas. Furthermore, the Native Fish Conservation Areas have increased awareness of the ecological, recreational, and economic values of freshwater systems in the region, and helped increase interest and capacity of local landowners, communities, and recreational users (e.g., paddlers, anglers) to act as advocates and local stewards of these systems. By facilitating partnership development, coordinating multi-species, watershed-based conservation planning, and leveraging technical and financial resources toward strategic conservation investments, Native Fish Conservation Areas have served as a catalyst for collaborative, science-based stewardship of native freshwater fishes and aquatic habitats in the southwestern USA. Efforts described herein to prioritize and deliver a network of Native Fish Conservation Areas in the southwestern USA offer a successful case study in multi-species and watershed approaches to freshwater fish conservation transferrable to other states and regions of the USA. This report offers a synthesis of recent (2011-2018) multi-species aquatic assessments, Native Fish Conservation Area prioritizations, conservation planning, and conservation delivery within the southwestern USA explicitly focused on implementation of the Native Fish Conservation Areas approach.
Gluesenkamp, Andrew, Dean A. Hendrickson, and Peter Sprouse. 2018. “The Mexican Blindcat Project: new discoveries and future efforts.” ARPHA Conference Abstracts 1: e29391. Publisher's VersionAbstract
The endangered Mexican blindcat (Prietella phreatophila, Carranza 1954) is one of only four described stygobitic ictalurid catfish in North America. Members of two monotypic genera (Satan eurystomus and Trogloglanis pattersoni) are known from the Edwards Aquifer in Texas and, until recently, Prietella (represented by P. lundbergi and P. phreatophila) was only known to occur in Mexico (northern Coahuila to southern Tamaulipas). The recent discovery of P. phreatophila in a cave on the Amistad National Recreation Area in Val Verde County, Texas is the result of decades of sporadic effort on both sides of the US/Mexican border and has stimulated a renewed effort to investigate the distribution, ecology, evolutionary history, and conservation status of this species. Collaborative efforts among The San Antonio Zoo, The University of Texas at Austin, Zara Environmental, and The National Park Service are currently focused on habitat surveys in Texas as well as captive husbandry and propagation. Ongoing efforts with collaborators from the Comisión Nacional de Áreas Naturales Protegidas, Área de Protección de Recursos Naturales Sabinas and the Laboratorio de Genética para la Conservación, Centro de Investigaciones Biológicas del Noroeste, La Paz include expanded fieldwork in Mexico, hydrogeologic studies, and surveys using environmental DNA.
Cohen, Adam E., Gary P. Garrett, Melissa J. Casarez, Dean A. Hendrickson, Benjamin J. Labay, Tomislav Urban, John Gentle, Dennis Wylie, and David Walling. 2018. “Conserving Texas Biodiversity: Status, Trends, and Conservation Planning for Fishes of Greatest Conservation Need.” Texas Parks and Wildlife Department - U.S. Fish and Wildlife Service State Wildlife Grant Program grant TX T-106-1 (CFDA\# 15.634)): 355. Publisher's VersionAbstract
The primary aim of this grant was to work with Texas Parks and Wildlife (TPWD), Texas Advanced Computing Center (University of Texas at Austin), and other collaborators to (1) utilize Fishes of Texas Project (FoTX) data to aid in conservation of Texas fishes, (2) conduct field surveys in under-sampled areas of conservation interest, and (3) further develop the FoTX database and website as a research and management tool. While much of our work focused on Species of Greatest Conservation Need (SGCN), almost everything we did was applied to all species, or affected data for all species. This report documents how FoTX’s specimen-based data were used to produce species distribution models that, in turn, fed into prioritization analyses that led to official creation of Native Fish Conservation Areas (NFCAs) that are now becoming the foundation of aquatic resource conservation prioritization and management in Texas. Our data were also used by TPWD staff to update the Texas Natural Diversity Database, previously depauperate for fish data, and to develop state and global conservation rankings for fishes using NatureServe’s standard methodology. Using FoTX data, we also developed recommendations for updating TPWD’s SGCN list, which will inform conservation in Texas for many years. We also expanded the scope of FoTX beyond Texas, throughout entire drainages, thus reducing biases and analytical complications related to our previous political boundary that lacked a biogeographical basis. We also added many new records from new types of data sources, especially agency databases that complement the museum specimen data to provide a more thorough, updated and unbiased dataset for analyzing temporal and spatial trends in fish faunas. The FoTX website’s checklists were improved in many ways to increase their utility to resource managers, and the site also now accesses occurrence data held in formerly inaccessible, but now digitized and easily accessed documents. We used diverse resources and our occurrence data to determine native ranges for all Texas fishes, and now visualize them in our website's maps, so when viewed alongside occurrence data, users can more easily recognize and explore spatial and temporal trends. We focused another effort at understanding range changes through time, and produced dynamic graphs, that when fully implemented will update automatically as underlying data evolve, depicting and statistically describing locational and general range size changes through time. In addition to database and website work, we were also in the field alongside, and in close coordination with, TPWD staff, focusing on collecting areas previously lacking data, or where there were other conservation-related reasons for sampling. The resultant thousands of new specimens and tissue samples deposited and permanently housed in the University of Texas Biodiversity Collections now provide new, modern data points for ongoing conservation actions. In summary, this project allowed FoTX to continue to grow and diversify, moving away from focusing solely on archiving and improving the data to applying those data in diverse ways that maximize their value for conservation. The project also greatly increased collaborations between FoTX and TPWD staff, and inspired a Herps of Texas Project templated on the FoTX database schema and website, thus providing an efficient pathway for getting that project to a similar state, with the added advantage of a high level of inter-compatibility of most improvements across both sites. Our hope is that other projects, focusing on other taxa, continue to follow in our footsteps, allowing mutual benefit, and eventually query interfaces that provide users access to high quality data for entire ecological communities.
Cohen, Adam, Dean Hendrickson, and Robert Edwards. 2018. “Temporal Changes in the Fishes of Waller Creek and Invasion of the Variable Platyfish”. Publisher's VersionAbstract
Waller Creek is an entirely urban creek flowing 11km through Austin, Travis County, Texas into Ladybird Lake. We gather the historic fish data, all held in our own Fishes of Texas Project database (Hendrickson and Cohen, 2018), for the creek and attempt to describe temporal change in the fauna of the creek. Minimal samples exist from the 1940’s and ’50s, but its fish fauna is rigorously sampled in the 1970’s when Edwards (1976) first formally surveyed the creek. It was uncollected in the 1980s. The Hendrickson lab, working with the public, local schools and universities, began sampling the creek in the 1990’s and continues to do so. These two sources (Edwards and Hendrickson Lab) are the main generators of data and we compared pre- and post-1980s data largely generated by these two sources. The fish fauna remains dominated by the same seven species Edwards collected in the 1970s (Gambusia affinis, Campostoma anomalum, Astyanax mexicanus, Lepomis megalotis, Lepomis cyanellus, Cyprinella lutrensis, and Herichthys cyanoguttatus), with the exception of an invasive species (Xiphophorus variatus), first detected in 2004, that is now the dominant species in the creek. Two of these seven species are firmly established non-natives (Astyanax mexicanus and Herichthys cyanoguttatus). Most of the less common native species collected in the 1970’s are no longer present (Ameiurus melas, Dionda flavipinnis, Fundulus zebrinus, Lepomis humilis, Lepomis macrochirus) or rare (Cyprinella venusta, Micropterus salmoides, Pimephales promelas) based on the data.
Platania, Steven P., Dean A. Hendrickson, and Adam E. Cohen. 2018. “Documentation Related to a 1991 Observation of Sturgeon in the Rio Grande – Río Bravo, USA (Texas) and Mexico (Coahuila)”. Publisher's VersionAbstract
This digital archive provides a compilation of previously unpublished information regarding a 1991 observation of a live sturgeon (Family Acipenseridae) in the Rio Grande-Río Bravo of the USA and Mexico. Though a few specimens collected in the 19th century support occurrence of sturgeon in this river basin, lack of credible, recent records has often led to this species not being recognized as part of the basin’s native fish fauna, and certainly not part of its modern fish community. The second and third authors of this document manage the Fishes of Texas Project (Hendrickson, Dean A., & Cohen, Adam E. (2015). Fishes of Texas Project Database (version 2.0). Texas Advanced Computing Center, University of Texas at Austin. and knew of the unpublished 1991 observation of sturgeon reported here. They requested the content provided here from first author (Platania) who provided what follows below (verbatim as received in April 2018) and permission to archive it for public access.
Hendrickson, Dean A. 2018. “Fishes of Texas and the Colorado River, with Special Attention to American Eel”. Publisher's VersionAbstract
The Fishes of Texas Project is briefly described, selected species known from the Colorado River basin (Texas) are discussed, and the life cycle of the American Eel is outlined with special attention to the distribution and status of the species in Texas. Files here include the original PowerPoint, a PDF version of the slides only, and a PDF version of the slides and all notes covering most of what was presented orally at the Barstow Speaker Series of the Colorado River Alliance on March 5, 2018 in Austin, Texas (see
Williams, J.E., Daniel J. Isaak, J. Imhof, Dean A. Hendrickson, and J.R. McMillan. 2018. “Cold-Water Fishes and Climate Change in North America, 2018.” The Encyclopedia of the Anthropocene, 2: 103–111. Oxford, UK: Elsevier, 2, 103–111.
Hendrickson, Dean A. 2017. “American Eels in Texas – a review of what is known, what is being done to learn more, and how you can help.” Texas Commission for Environmental Quality's Annual Surface Water Quality Monitoring (SWQM) workshop. Bandera, Texas, USA. Publisher's VersionAbstract
This presentation reviews the current status of knowledge about the American Eel, its conservation status and distribution in Texas, and work in progress to learn more about the species in Texas.
Lundberg, John G., Dean A. Hendrickson, Kyle R. Luckenbill, and Mariangeles Arce H. 2017. “SUPPLEMENTARY ANIMATIONS & DATA FOR: Satan’s skeleton revealed: a tomographic and comparative osteology of Satan eurystomus, the subterranean Widemouth Blindcat (Siluriformes, Ictaluridae). Proceedings of the Academy of Natural Sciences of Philadelphia ”. Publisher's VersionAbstract
The Widemouth Blindcat, Satan eurystomus Hubbs and Bailey 1947, was the second of four stygobitic species of Ictaluridae discovered in the subterranean waters of southern Texas and northeastern Mexico. The skeletal anatomy of Satan has been scarcely known from a few, dated radiographs. Using additional radiographs and high resolution CT-datasets for two well-ossified specimens, we applied high-resolution X-ray computed tomography (HRXCT) to visualize, illustrate and describe the bony skeleton of Satan. We also provide an online archive of still and animated tomographic images of the skeletal anatomy of this little-known species. The skeleton and soft anatomy of Satan are distinctive. Twelve skeletal autapomorphies are described that singularly distinguish Satan within Ictaluridae and, probably in combination, from all other catfishes. Some of these are reductive losses or simplifications of skull bones (e.g. loss of one infraorbital bone; reduced ornamentation of the pterotic bone) and joint complexity (e.g. simple overlapping frontal-lateral ethmoid articulation; loosely ligamentous interopercle-posterior ceratohyal joint). Some of the autapomorphies are anatomically and perhaps developmentally complex (e.g. a novel series of three midline joints closing a middle span of the posterior cranial fontanel; a deeply excavated temporal fossa and an unusually enlarged interhyal bone). The tiny dorsal-fin spinelet (first lepidotrich) of Satan has a novel peaked and twisted shape. Ten apparent and exclusive synapomorphies within Ictaluridae gathered from this and previous studies suggest that Satan and Pylodictis are closest relatives. Most of these are functionally related to prey detection and suction feeding: fusion of the symphyseal mandibular sensory pores and increase in the number of preoperculo-mandibular canal pores; depressed, flattened heads and wide transverse mouths; prominent posterior process of the lateral ethmoid alongside and below the frontal bone margin; vertical and blade-like supraoccipital posterior process; unique arrangement of the parasagittal and occipital muscle-attachment crests on the skull roof; large triangular panel of integument within the operculum framed by the opercle, preopercle and interopercle bones; elongated posterior ceratohyal; and, form of the fourth supraneural and loss of its anterior nuchal plate. In contrast, fifteen synapomorphies recovered by Arce-H. et al. 2016, are confirmed suggesting that Satan is one of the four stygobitic ictalurids comprising a “Troglobites” subclade within the family: (Trogloglanis, Satan, Prietella phreatophila, P. lundbergi). These features include three stygomorphic and reduction apomorphies that are exclusive within Ictaluridae: loss of fully developed eyes and pigmentation, and simplification of the fifth vertebra and its joint with the Weberian apparatus. Twelve other synapomorphies shown by the Troglobites are also apparent homoplasies of character states shared with various other ictalurids. These include reductive characters such as shortened lateral line canal, reduced infraorbitals and underdeveloped or incomplete ossifications of the pterotic, supraoccipital, hyoid arch bones and transcapular ligament. Also, the Troglobites and various other ictalurids have: an adnate adipose-caudal fin, foreshortened anterior cranial fontanelle, reduced ventral wings of the frontal bone, replacement of bone by cartilage in hypohyal joints; incompletely ossified transcapular ligament, and consolidation of some hypural bones. Completing a full morphological character dataset across the Troglobites has been impeded by incomplete specimen preparations and study of P. lundbergi and to a lesser extent, P. phreatophila and Trogloglanis.
Beal, Andria P., F. Douglas Martin, and Matthew C. Hale. 2017. “Using RNA-seq to determine patterns of sex-bias in gene expression in the brain of the sex-role reversed Gulf Pipefish (Syngnathus scovelli).” Marine Genomics. Publisher's VersionAbstract
Sex-bias in gene expression is a widespread mechanism for controlling the development of phenotypes that differ between males and females. Most studies on sex-bias in gene expression have focused on species that exhibit traditional sex-roles (male-male competition and female parental care). By contrast the Syngnathid fishes (sea horses, pipefish, and sea dragons) are a group of organisms where many species exhibit male brooding and sex-role reversal (female-female competition for mates and paternal parental care), and little is known about how patterns of sex-bias in gene expression vary in species with sex-role reversal. Here we utilize RNA-seq technology to investigate patterns of sex-bias in gene expression in the brain tissue of the Gulf Pipefish (Syngnathus scovelli) a species that exhibits sex-role reversal. Gene expression analysis identified 73 sex-biased genes, 26 genes upregulated in females and 47 genes upregulated in males. Gene ontology analysis found 52 terms enriched for the sex-biased genes in a wide range of pathways suggesting that multiple functions and processes differ between the sexes. We focused on two areas of interest: sex steroids/hormones and circadian rhythms, both of which exhibited sex-bias in gene expression, and are known to influence sexual development in other species. Lastly, the work presented herein contributes to a growing body of genome data available for the Syngnathids, increasing our knowledge on patterns of gene expression in these unusual fishes.
Garrett, Gary, Megan Bean, Robert Edwards, and Dean Hendrickson. 2017. “Declines and Losses of Spring/Ciénega Ecosystems in the Chihuahuan Desert of Texas”. Publisher's VersionAbstract
Desert ecosystems are particularly susceptible to anthropogenic influences. This is especially true for desert aquatic systems where limited water resources can be easily impaired by excessive water mining depleting the underlying aquifers. Although the aquatic environments and their associated native fishes are declining throughout the Chihuahuan Desert, we will focus on examples from the Big Bend region, the Balmorhea Springs Complex, the Pecos River region, and the Devils River region. Ongoing and impending land use and water consumption patterns suggest even further reductions in the near future. Even though numerous conservation activities are underway, archaic Texas water laws must be revisited and reformulated if the desert aquatic systems are to be truly conserved for more than the immediate future.
Dugan, Laura E., Dean A. Hendrickson, Antonio Hernández-Espriú, Gary P. Garrett, Adam E. Cohen, Brad Wolaver, and Ryan Smith. 2017. “Conservation status assessment of the endangered Mexican Blindcat, Prietella phreatophila”. Publisher's VersionAbstract
Discovery of the Mexican blindcat, Prietella phreatophila, in Texas in 2016 generated interest in the species, which had previously only been known from Mexico but is listed as a foreign endangered species in the US. Consequently, an effort was undertaken to conduct a conservation status assessment of the fish using standardized methods developed by NatureServe. These assessments aim to determine the extinction risk of species and produce conservation ranks, which can be used to inform listing statuses and policy decisions and to determine conservation priorities. The rank is determined by assessing factors in three main categories: rarity, threats, and trends. Here we used three rarity and one threat factor in the NatureServe rank calculator to determine the global conservation rank of P. phreatophila. Known occurrences were compiled, and the online tool GeoCAT (geospatial conservation assessment tool) was used to determine range extent and area of occupancy. Number of occurrences (e.g., populations) was estimated based on the spatial distribution of observations and their proximity to one another. Threat comprised scope, which was assessed in ArcGIS by intersecting the total area covered by a given threat with the known occurrence area of P. phreatophila, and severity, which was estimated based on expert opinion. The resulting conservation rank was G2 (globally imperiled; roughly equivalent to IUCN’s Vulnerable rank); however, complete data were not available for any factor thus motivating the need for further study. When new data are available, the rank can be easily updated with this new information using the rank calculator.
Hendrickson, Dean A., Antonio Hernández-Espriú, Laura Dugan, Peter Sprouse, José Antonio Dávila Paulín, Jean Krejca, Andrew Gluesenkamp, et al. 2017. “Discovery of Endangered Mexican Blindcat, Prietella phreatophila, in Texas: Implications for International Groundwater Management and Evolution of the Regional Karst Aquifer Biota”. Publisher's VersionAbstract
Mexican blindcat, Prietella phreatophila, described in 1954 from a cave system near the town of Múzquiz in central Coahuila state, and considered a Mexican endemic, was listed by the U.S. Fish and Wildlife Service as a foreign endangered species (protected "wherever found") in 1970. Explorations in the 1990s discovered many new localities extending nearly to the international border, and in 2016 the species was discovered in Amistad National Recreation Area (ANRA) in Texas, just north of the international border near Del Rio. Not only does the discovery support the aquifer of this fish being an internationally shared resource, but the stygobitic invertebrate biota found with the fish indicates a potentially large extent of the aquifer, and thus possibly the fish, in Texas. Invertebrate faunal connections (historic or current) extend from the Amistad Lake area of the new occurrence west into the Trans-Pecos region and east into the Edwards Aquifer of central Texas. We explore implications of this for both water management and evolutionary history of this and other blind ictalurids, and suggest that population genetic studies of both stygobitic fishes and invertebrates could help hydrogeologists better define often difficult to map aquifer extents and interconnections. While NPS is continuing to support the cave explorations of ANRA that produced the Texas discovery, we propose a broader bi-national sampling effort for both the fish and invertebrates extending well beyond the current known distribution of P. phreatophila. We also pointed out questions about phylogenetic relatedness of P. phreatophila and P. lundbergi further south, as well as the possibility of a monophyletic clade of blindcats, including those of the Edwards Aquifer, Satan and Trogloglanis. If substantiated, that evolutionary history would imply broader historic inter-aquifer connections ranging from the San Antonio area as far south as southernmost Tamaulipas. Finally, we report establishment of a small captive population of Prietella phreatophila at San Antonio Zoo for research and possibly eventual conservation applications.
Gluesenkamp, Andrew, Dean A. Hendrickson, and Peter Sprouse. 2017. “The Mexican Blindcat Project: new discoveries and future efforts”. Publisher's VersionAbstract
The endangered Mexican blindcat (Prietella phreatophila, Carranza 1954) is one of only fourstygobitic ictalurid catfish in North America. Members of two monotypic genera (Satan eurystomus and Trogloglanis pattersoni) are known from the Edwards Aquifer in Texas and, until recently, Prietella (represented by P. lundbergi and P. phreatophila) was only known to occur in Mexico (northern Coahuila to southern Tamaulipas). The recent discovery of P. phreatophila in a cave on the Amistad National Recreation Area in Val Verde County, Texas is the result of decades of sporadic effort on both sides of the US/Mexican border and has stimulated a renewed effort to investigate the distribution, ecology, evolutionary history, and conservation status of this species. Collaborative efforts among The San Antonio Zoo, The University of Texas at Austin, Zara Environmental and The National Park Service are currently focused on habitat surveys in Texas as well as captive husbandry and propagation. Future efforts will include collaborators from the Comisión Nacional de Áreas Naturales Protegidas, Área de Protección de Recursos Naturales Sabinas, and the Laboratorio de Genética para la Conservación, Centro de Investigaciones Biológicas del Noroeste, La Paz to conduct expanded fieldwork in Mexico, hydrogeologic studies, and surveys using environmental DNA.
Lundberg, John G., Dean A. Hendrickson, Kyle Luckenbill, and Mariangeles Arce H. 2017. “Satan’s Skeleton Revealed”. Publisher's VersionAbstract
Satan eurystomus Hubbs & Bailey 1947, the widemouth blindcat, is endemic to the deep Edwards Aquifer below San Antonio, TX. Monotypic Satan is one of four subterranean ictalurids, Trogloglanis pattersoni, Prietella pheatophila and P. lundbergi, that all exhibit common features of stygomorphs: loss of eyes and pigmentation, hypertrophy of some chemo and mechanosensory systems, small size, and variously reduced musculoskeletal system. Each species is distinctive in its own ways, and hypotheses about their phylogenetic positions range from separate ancestries of each scattered among the lineages of epigean ictalurids to exclusive monophyly of a strictly subterranean clade. Specimens of Satan are rare, thus we used highresolution CT scans to develop the first detailed, richly illustrated descriptive and comparative study of its skeleton. Satan exhibits typical and singular reductive features plus complex structures, e.g. 3 novel symphyses closing the posterior cranial fontanel; an unusually deep temporal fossa; and an ornately shaped dorsal fin locking spinelet. Satan shares 15 synapomorphies with other ictalurid troglobites: the stygomorphisms plus bone and joint reductions. Satan shares 11 synapomorphies with Pylodictis, including increased numbers of cephalic sensory pores and paired fin rays, and several features associated with predatory suction feeding: wide gape, depressed head, expanded branchiostegal and opercular membranes and anterior extension of epaxial muscle. Incomplete character information, including lack of molecular data for Satan and Trogloglanis, poor quality of available skeletal preparations for Trogloglanis and Prietella, and uncertain identifications of some specimens of Prietella impede construction of a complete dataset for phylogenetic analysis.
Hendrickson, Dean A., Jack Johnson, Peter Sprouse, Sarah Howard, Gary P. Garrett, Jean K. Krejca, Andrew Gluesenkamp, et al. 2017. “Discovery of the Mexican Blindcat, Prietella phreatophila, in the U.S., and an update on its rangewide conservation status.” Proceedings of the Texas Academy of Sciences. Mary Hardin Baylor University, Belton, Texas. Publisher's VersionAbstract
Mexican blindcat, Prietella phreatophila, was described in 1954 from a single locality in Northern Coahuila, México. Long listed as endangered by the Mexican federal government, it was listed by the U.S. Fish and Wildlife Service as a foreign endangered species in 1970, and the most recent (1996) update of its assessment for the IUCN Red List considers it endangered as well. Explorations in the late 1990s discovered many new localities extending nearly to the international border, and a captive population established provided insights into the species’ basic biology and behavior. In 2016 the species was discovered in a cave in the Amistad National Recreation Area (ANRA), just north of the Río Grande in Texas. The 1970 listing instantly gave the TX population full protection under the U.S. Endangered Species Act. The species’ subterranean and mostly inaccessible habitat endows it with extremely low detectability and its actual range is likely broader than physical sampling of specimens has revealed. We review all prior and new knowledge of the species and its habitat to provide an updated international reassessment of its overall conservation status and threats, which most notably include aquifer depletion and contamination in both the Mexican and U.S. portions of its known range. A live captive population of two specimens collected in 1997 in Coahuila and one Texas specimen is now at the San Antonio Zoo, we are working with NPS to further explore ANRA caves and hope eventually to return to Coahuila to more fully update the species’ conservation status.
Pine, W. E., K. Limburg, B. Gerig, C. Finch, D. Chagaris, L. Coggins, D. Speas, and D.a. Hendrickson. 2017. “Growth of Endangered Humpback Chub in Relation to Temperature and Discharge in the Lower Colorado River.” Journal of Fish and Wildlife Management 8 (1): 322–332. Publisher's VersionAbstract
Assessments of growth can provide information needed to understand how fish populations respond to changing environmental conditions and management actions, including ecosystem experimentation. We estimated growth rates and parameter uncertainty from otoliths of endangered Humpback Chub Gila cypha from the Colorado River in Grand Canyon, Arizona. We then compared growth of Humpback Chub \textless age 2 that were 1) occupying the mainstem Colorado River during a period of variable discharge and cooler water temperatures (1980–1998; epoch 1), 2) occupying the Colorado River during a period of moderate discharge variability and warmer water (2001–2011; epoch 2), and 3) occupying the unregulated Little Colorado River. Because growth rates of juvenile Humpback Chub (\textless age 2) may be more sensitive to changes in environmental conditions than adult fish, we used analysis of covariance and linear models to compare growth of juvenile fish (slopes) between epochs and capture sites (mainstem Colorado River vs. Little Colorado River). Our analysis of covariance results were ambiguous (age × epoch × site interaction; P = 0.06). However, individual linear regressions of size and age by epoch and site suggest biologically important differences in growth, as evidenced by slower growth in the Colorado River in epoch 1 than in epoch 2, and slower growth in the Colorado River compared with the Little Colorado River for all time periods. Overall our results 1) provide information on growth and growth variability useful for parameterizing models to assess population viability and 2) provide empirical information on how growth of juvenile and adult Humpback Chub growth may respond to changing environmental conditions.
Hendrickson, Dean A. 2017. “Utility of Mining of Diverse Historic and Current Data Sources for Insights into Distribution and Ecology ofAmerican Eels in the Gulf of Mexico and Its Tributaries.” F1000Research 6. Publisher's VersionAbstract
Compilation of basic occurrence records of American Eel in Texas revealed not only a general paucity of data, but also biases of different sources, and overall, inaccessibility of many different sources of useful records. Methodical searching, mining, normailization and basic data cleaning across a diversity of resources provided a much better picture of temporal and spatial occurrences of the species than had readily available sources. Similar data mining and sharing by all researchers and managers could greatly improve overall understanding of the species in the GoM and its tributaries, and help focus monitoring and research efforts.
Hendrickson, Dean A. 2016. “Prologo.” La Trucha Dorada Mexicana, 1st ed., v–vii. México: Arturo Ruiz Luna and Francisco García de León, v–vii. Publisher's Version