ABSTRACT. Desert fish populations are declining and disappearing throughout the Southwest United States and Mexico. Over millennia, desert fishes have adapted to extreme and highly variable climate, ecological, and geomorphologic conditions. However, in recent decades native desert fish populations have significantly declined due to increased anthropogenic impacts, including water consumption, fragmentation, non-native species interactions, and habitat degradation. As the climate crisis accelerates, it is no surprise that we are witnessing severe declines of our water dependent desert ecosystems. Without directed and sustained species conservation efforts there will be a continued decline in these unique and ecologically valuable fish species. Some of the most vulnerable ecosystems and species in the current catastrophe continue to decline and their long-term survival will rely heavily on consistent dedication of technical, social, and political resources on local and national scales. However, we rarely see consistent attention or public support (e.g., from local communities, policymakers, environmental organizations) in terms of desert fish conservation. Too frequently have desert fish biologists heard the question, “There are fish in the desert?”. Previous pursuits of recognition for desert fishes, such as the Devil’s Hole pupfish (Cyprinodon diabolis) or the Owens Pupfish (Cyprinodon radiosus), have been successful, but many others have fallen short of securing this crucial support. Here, we aim to investigate outreach, opinions, and the theoretical foundation for greater desert fish engagement while identifying methods for lasting support. We distributed a survey through several professional fisheries organizations asking for thoughts on fisheries outreach and potential methods of success. With 307 responses, we gained insight from scientists from regions across the United States on public outreach importance, successes, and barriers. We compared responses among regions and species to investigate the role of geographic influence on public recognition. Responses have indicated individuals highly value outreach, but many would like to have the same level of involvement as they currently do. With these results taken directly from scientists and researchers, we hope to begin a deeper investigation into successful outreach and support with an in-depth literature review and continued conversation. As a nation and society, we must provide increased recognition for these species, as they continue the battle against extinction.

ABSTRACT. Catfishes of the genus Ictalurus (Ictaluridae) range geographically from southern Canada to northern Guatemala and Belize. The systematics of this genus remain unresolved, with recent studies suggesting the presence of cryptic diversity. This is the case for a potentially undescribed catfish species distributed in the Nazas River basin, which has been recorded to date as a population of Ictalurus pricei. Recent phylogenetic studies suggest that it represents an independently evolving lineage that is distinct from I. pricei. This study aimed to determine the diagnostic characters that differentiate the Nazas River basin lineage and to describe this lineage as a new taxon. Morphological comparisons were made using meristic and morphometric characters. The study identified useful meristic and morphometric characters for diagnosing Ictalurus nazas sp. nov., which differentiate it from I. pricei.

ABSTRACT. The Candela River is located within the Salado River, a tributary of the Río Grande basin, in Coahuila, Mexico. In addition to its surface aquatic ecosystems, the Candela River includes a cave system that represents a hypogean ecosystem, where three species of freshwater fish have been recorded, each belonging to the genera Ictalurus, Astyanax, and Herichthys. The present study focused on the taxonomic identification to species level of specimens belonging to Ictalurus. Within the native ichthyofauna of the Río Grande basin, the species Ictalurus punctatus, Ictalurus lupus, and Ictalurus furcatus are known to occur. Herein, taxonomic identification was performed using both morphological and molecular characters from seven sampled specimes, including mitocondrial and nuclear loci. The morphological assessment included linear measurenments (e.g. head length vs. anal fin base length), meristic counts (e.g. number of anal fin rays), and other distinctive traits such as the shape of the distal margin and tips of the caudal fin. For the molecular analysis, sequences from both loci were aligned with a broad dataset retrieved from GenBank. A Maximun Likelihood phylogenetic reconstruction, conducted separately for each locus, was then employed to assess the taxonomic assignment of the cave population. Results revealed a discrepancy between morphological, mitocondrial and nuclear data what suggests a complex evolutionary history for the Ictalurus population inhabiting the Candela River cave system. Morphological characters were ambiguos, exhibiting a combination of traits typical of both I. punctatus and I. lupus. Meanwhile, phylogentic reconstruction based on mitochondrial locus placed all cave specimens within I. punctatus, whereas the nuclear locus grouped them within I. lupus. Such observed discrepancy has important evolutionary implications. First, this pattern may indicate historical or recent hybridization between the two species, with the mitochondrial signal reflecting maternal ancestry from I. punctatus and the nuclear signal revealing biparental contributions from I. lupus. Second, the mitocondrial assignment to I. punctatus may suggest a case of complete mitochondrial introgression, meaning that sufficient time has passed for the mitochondrial genoma to become fixed within the population. Finally, the morphological ambiguity may be driven by local adaptation to the hypogean environment, leading to phenotypic convergence or reduction of diagnostic traits due to relaxed selective pressures. Nevertheless, further studies including genome-wide nuclear markers and broader sampling across both surface and cave populations are necessary to clarify the taxonomic status and evolutionary dynamics of this unique population.

ABSTRACT. The fish fauna of the Ciénega de Santa Clara is almost entirely composed of exotic species, and only one location in the southeast of the marsh maintains a healthy population of the desert pupfish,(Cyprinodon macularius). During 2022 and 2023, an ecosystem restoration project was carried out under the Program for the Protection and Restoration of Ecosystems (PROREST) of the National Commission of Natural Protected Areas in México (CONANP). The purpose of this project was to know about the distribution of invasive species in the wetland, as well as their interactions with the desert pupfish and the impacts they have on wetland ecosystems in the Upper Gulf of California and Colorado River Delta Reserve, especially the plecos (Pterygoplichthys sp). Additionally, 10 ejido members were trained in the use and operation of fish trapping methods to promote the permanent implementation of a protocol for the removal of exotic fishes for its population control, especially in the Ciénega de Santa Clara and the El Doctor wetlands, which are critical habitat for the desert pupfish. For 63 days, work was carried out on trapping exotic species and rehabilitating 35 hectares of wetland areas to reactivate water flow through feeder channels to a pond specifically constructed to serve as a potential reservoir for desert pupfish within an interpretive trail at the Ciénega Santa Clara. A total of 65 kilograms of biomass from exotic species were collected and composted in designated compost pits. At the end of the project, 900 meters of channels were improved to better supply water to the aforementioned reservoir.

ABSTRACT. The Sonoyta pupfish (Cyprinodon eremus) is an endemic species of the Sonoyta River basin (Sonora) and the Quitobaquito springs (Arizona). The population faces problems of anthropogenic origin. As conservation strategies, five refuges were built in Sonora for the species. However, recent studies at the refuge at Sonora Ecological Center (CES) in Hermosillo indicate that they present a genetic imbalance caused by a heterozygote deficit. Fixation indices indicate little genetic differentiation and a high coefficient of inbreeding. In contrast, population sampling has recently been carried out in the CES pond, indicating that it is the refuge with the largest number of individuals. The refuge was created in 1988 and has remained intact since then, except for the genetic analysis that was carried out in 2023. The pond has been slowly silting up, and exotic species (pond slider turtles and mosquitofish) have appeared. Although species control measures have been implemented, the silting requires further attention. In addition, we are remodeling the pond to create a stream and include pools, rocks, and native plants from the Sonoyta River. With the refuge's renovation, we expect the genetic health of the Sonoyta pupfish will improve, due to the diversity of environments we will create: pond, stream, pools, and the presence of native plants. This will make it the largest refuge in Sonora, with the largest number of individuals, ideal for exchanges with other refuges.

ABSTRACT. Desert fish populations are declining and disappearing throughout the Southwest United States and Mexico. Over millennia, desert fishes have adapted to extreme and highly variable climate, ecological, and geomorphologic conditions. However, in recent decades native desert fish populations have significantly declined due to increased anthropogenic impacts, including water consumption, fragmentation, non-native species interactions, and habitat degradation. As the climate crisis accelerates, it is no surprise that we are witnessing severe declines of our water dependent desert ecosystems. Without directed and sustained species conservation efforts there will be a continued decline in these unique and ecologically valuable fish species. Some of the most vulnerable ecosystems and species in the current catastrophe continue to decline and their long-term survival will rely heavily on consistent dedication of technical, social, and political resources on local and national scales. However, we rarely see consistent attention or public support (e.g., from local communities, policymakers, environmental organizations) in terms of desert fish conservation. Too frequently have desert fish biologists heard the question, “There are fish in the desert?”. Previous pursuits of recognition for desert fishes, such as the Devil’s Hole pupfish (Cyprinodon diabolis) or the Owens Pupfish (Cyprinodon radiosus), have been successful, but many others have fallen short of securing this crucial support. Here, we aim to investigate outreach, opinions, and the theoretical foundation for greater desert fish engagement while identifying methods for lasting support. We distributed a survey through several professional fisheries organizations asking for thoughts on fisheries outreach and potential methods of success. With 307 responses, we gained insight from scientists from regions across the United States on public outreach importance, successes, and barriers. We compared responses among regions and species to investigate the role of geographic influence on public recognition. Responses have indicated individuals highly value outreach, but many would like to have the same level of involvement as they currently do. With these results taken directly from scientists and researchers, we hope to begin a deeper investigation into successful outreach and support with an in-depth literature review and continued conversation. As a nation and society, we must provide increased recognition for these species, as they continue the battle against extinction.

ABSTRACT. The Yaqui catfish, Ictalurus pricei, is native to northwestern Mexico and southwestern United States and is endangered by habitat alteration, water over-extraction, and the introduction of non-native species. Among these, competition and hybridization with the introduced channel catfish, Ictalurus punctatus, represent a major threat to remaining Yaqui catfish populations. Here, Ecological Niche Modeling (ENM) was used based on historical and contemporary occurrence records of both species to assess niche overlap and potential geographical areas of co-ocurrence. Due to hybridization risks, only pure Yaqui catfish individuals previously identified through mitochondrial and nuclear genes were considered in recent records. The ENMs were calibrated considering fifteen uncorrelated environmental variables in the natural distribution areas of the species. Minimum Volume Ellipsoid (MVE) approach was used to characterize each species’ niche and project those niches geographically. The MVE showed a broader ecological niche for channel catfish than for Yaqui catfish. Significant niche overlap between Yaqui and channel catfish (p < 0.05) was found, and geographical projection in the Yaqui catfish distribution, revealed multiple areas of suitable habitats shared by both species. These results reflect the niche similarity between both species, which is expected due to its close phylogenetic relationship, highlighting the risk of extirpation of the remnant Yaqui catfish populations due to competition and hybridization with channel catfish. We recommend expanded sampling across the Yaqui catfish range and integrated use of genetics, genomics and niche modeling to guide conservation and management actions aimed at preserving the genetic integrity and persistence of Yaqui catfish.

ABSTRACT. Bonita Creek, a tributary of the Gila River near Safford in southeastern Arizona, supports a diverse assemblage of native fish species and is managed by the Bureau of Land Management to promote native fish conservation. Approximately 15 miles of the creek, downstream of the boundary with the San Carlos Apache Indian Reservation, are mostly perennial and currently provide habitat for native species, including Gila Chub Gila intermedia, Sonora Sucker Catostomus insignis, Longfin Dace Agosia chrysogaster, Speckled Dace Rhinichthys osculus, Desert Sucker Pantosteus clarkii, and Gila Topminnow Poeciliopsis occidentalis. A key management goal is the establishment and recovery of other imperiled species: Spikedace Meda fulgida, Loach Minnow Tiaroga cobitis, and Desert Pupfish Cyprinodon macularius. However, the presence of the invasive Yellow Bullhead Ameiurus natalis, first detected in 2011 in lower Bonita Creek, poses a significant threat to native fish through predation and competition. In response, mechanical removal efforts using backpack electrofishing and baited trapping have been implemented. These efforts aim to fully extirpate Yellow Bullhead from Bonita Creek by the end of 2025, thereby enhancing conditions for native fish restoration and long-term ecosystem resilience.

ABSTRACT. La reciente evaluación de los peces de agua dulce mexicanos utilizando los criterios de la Lista Roja de la UICN (Lyons et al. 2020), identificó 44 especies en peligro crítico de extinción, y entre estas se encuentra la Platilla de Tamazulapam (Astyanax salvatoris). Un estudio reciente que tuvo como objetivo definir las prioridades de conservación de los peces de agua dulce mexicanos y el desarrollo de un modelo de intervención (Contreras-MacBeath et al. 2022), mostró que existen al menos 8 especies, entre ellas A. salvatoris, que habitan en manantiales que son utilizados como parques acuáticos y que es necesario implementar modelos de conservación que permitan el desarrollo sostenible de esta actividad económica, pero con la protección de especies en riesgo. La Platilla de Tamazulapam se ajusta precisamente a este escenario, ya que es una especie que vive únicamente en una serie de manantiales en las inmediaciones de la comunidad Tamazulapan, Oaxaca, que son usados como Balnearios. Con base en lo anterior, este proyecto tiene como objetivo mejorar el conocimiento de la abundancia, distribución, amenazas actuales y potenciales a las que está sujeta la especie; realizar un proceso de planificación participativa con los miembros de la comunidad local que gestiona y administra los manantiales para desarrollar una estrategia de conservación que permita, por un lado, mejorar su manejo sustentable y, por el otro, asegurar la protección a largo plazo la Platilla de Tamazulapam. Gracias a las primeras fases del trabajo en campo ha sido posible establecer una muy productiva relación de trabajo con las autoridades ejidales quiénes son los responsables de los manantiales y del manejo del agua. Eso es permitido realizar trabajo de campo dónde se obtuvieron los primeros registros fotográficos y videográficos del especie. Los datos preliminares indican que la especie se distribuye en un área de tan solo cuatro hectáreas y se han identificado como amenazas perturbaciones al hábitat por parte de los operadores de los manantiales y de los visitantes, la presencia, aunque no en toda el área de especies invasoras como Poecilia reticulata, Pseudoxiphophorus bimaculatus, Xiphophorus helleri y Tilapia sp. Ahora, en colaboración con la comunidad, se está trabajando en el diseño de una estrategia para la conservación de la especie. Esperamos que este proyecto pueda convertirse en un modelo de intervención que pueda ser aplicado a otros parques acuáticos en México.

ABSTRACT. The Santa Cruz River is a major tributary of the Gila River in southern Arizona that has experienced dramatic habitat loss and alteration over the last 120 years. Historically, there were multiple perennial reaches on the mainstem of the river, interspersed with intermittent and ephemeral reaches, the combination of which supported a rich aquatic vertebrate fauna. Our goal here is to document historical records of fish, amphibian, and reptile species from the mainstem Santa Cruz River and contrast those records with modern-day species distributions. The historical (pre-1940) fauna included 6 native and 1 non-native species of fishes, 8 amphibian species, and 3 aquatic reptile species. With the exception of small parts of its headwaters, all perennial reaches of the river were dry by 1940 due to water withdrawals. However, treated effluent from wastewater treatment plants has restored flow in some of these reaches since the 1970s. Additionally, Tucson city managers have added flow to two additional reaches since 2019. Currently, 1 of the historical fish species is extinct (Santa Cruz Pupfish [Cyprinodon arcuatus]), 3 are likely extirpated from the mainstem river in Arizona, and 2 are extant (Gila Topminnow [Poeciliopsis occidentalis] and Longfin Dace [Agosia chrysogaster]). Amphibians and reptiles have fared better, with 7 of 8 amphibians and all 3 aquatic reptiles extant, but with greatly reduced distributions. The modern fauna of the river also includes 7 non-native fish species, 1 hybridogenetic fish species of unknown origin (Poeciliopsis monacha-occidentalis), and at least 3 non-native amphibians and reptile species. Additional surveys are needed in the headwaters of the river, where other native species may yet persist, and annual surveys should continue to monitor for non-native species in the rest of the mainstem. Recent reintroduction efforts (e.g. Gila Topminnow and Sonora Mud Turtle [Kinosternon sonoriense]) in downtown Tucson) have proven successful, and continued close collaboration between biologists and water managers could create additional restoration opportunities.

ABSTRACT. Gila Topminnow, Poeciliopsis occidentalis, a USFWS Listed Endangered Species, was rediscovered in the main stem of the Santa Cruz River in 2015. Genetic analyses (Mussman et al. 2023) revealed the presence of an exotic Poeciliopsis species, the hybridogenic Poeciliopsis monacha–occidentalis, also in the Santa Cruz main stem. We examined demographics among P. occidentalis, P. monacha-occidentalis and Mosquitofish (Gambisua affinis) in the river across eight geographic localities in the United States from annual collections made from 2016 to 2024. Sites are located from Nogales, Arizona where the Santa Cruz River reenters the United States to Marana north of Tucson. Subsamples were originally collected during an annual fall fish survey in the Santa Cruz River to determine Mosquitofish and Topminnow populations given difficulty in field identification of these species. These collections are part of the Sonoran Institute annual Living River Reports. They provide an invaluable opportunity to determine geographic and temporal changes in the distributions of the three species during this period of changing ichthyofauna composition in the Santa Cruz River. Currently we have completed an analysis regarding abundance and sex ratios of both Topminnow and Mosquitofish across the sites and years. The faunal composition shows a decreasing number of Mosquitofish, an increasing abundance of female Poeciliopsis species across sites and time. We demonstrate that P. occidentalis and P. monacha-occidentalis can be distinguished by examining dentition. The P. monacha-occidentalis is present in samples 2016 and becomes the prevalent Poeciliopsis over time. This suggests that the recovery of Poeciliopsis in the Santa Cruz River is not solely due to the upgrade of the water treatment facilities prior to the rediscovery. We suggest that the hybridogenetic species played an important role in the return of P. occidentalis to the Santa Cruz by out-competing G. affinis but requires P. occidentalis males for reproductive success.

ABSTRACT. The genus Agosia ranges from the Gila River basin in the southwestern United States to the Sinaloa River in northwestern Mexico. Currently, two forms are recognized based on morphometric analysis, without genetic evidence, the longfin dace (Agosia chrysogaster), with a northern distribution (Gila, Sonoyta, and de La Concepción river basins), and an undescribed form, from the Sonora River southward. As a monotypic genus, its populations were considered threatened in 2010, however, A. chrysogaster is now considered endangered under PROY-NOM-059-2025. The objective of this study is to use mitochondrial (COXI, Cyt-b, and ND2) and nuclear (RAG1) genes to evaluate the species identity and phylogenetic relationships. To date, the results from both mitochondrial and nuclear DNA analyses have identified four phylogenetic lineages, the A. chrysogaster clade, the Sonora River clade, the Yaqui and Mayo Rivers clade, and the Sinaloa River clade.

ABSTRACT. Our primary goal was to evaluate the status of the Rio Concepcion Topminnow, Poeciliopsis jackschultzi, an endangered cienega-specialist and microendemic that historically occupied ca. 30 km stretch of the Rio De La Concepcion, Sonora, Mexico. Survey efforts are hampered by the inability to use external morphology to distinguish P. jackschultzi from its co-occurring congeners: Poeciliopsis occidentalis and Poeciliopsis asexual hybrids. We used environmental (e)DNA analyses (metabarcoding with the “MiFish” primer set) to document fish taxa in the known range of P. jackschultzi, and in nearby localities and tributaries in 2022 and 2023.

Unfortunately, we did not detect a single eDNA sequence derived from P. jackschultzi, suggesting that it was absent or at an abundance below our detection ability. Multiple former freshwater fish habitat sites were completely dry.

Overall, eDNA from the native leuciscids Agosia chrysogaster and Gila ditaenia was most abundant. eDNA from the asexual hybrid and P. occidentalis was the 5th and 6th highest. We detected eDNA from the following previously documented non-native taxa: Lepomis cyanellus (3rd highest); Tilapia (4th highest); Ameiurus melas; Gambusia affinis; Lepomis macrochirus; and Micropterus salmoides. We document a recent introduction (Xiphophorus helleri) and the likely extirpation of Poeciliopsis spp. from above the Presa Comaquito (Arroyo Cocospera).

A secondary goal was to survey the Mexican side of the nearby Rio Santa Cruz (Gila River), where we confirmed the presence of the natives A. chrysogaster and P. occidentalis, and of the asexual hybrid (considered non-native). We also detected eDNA from a sucker and a chub, which surprisingly did not match the sequences of the respective native Santa Cruz taxa (i.e., Pantosteous clarkii or Catostomus insignis, and the Gila robusta complex). Instead, they perfectly matched, respectively, Catostomus bernardini and Gila minacae; native to other rivers.

ABSTRACT. Research on North America’s desert fishes spans more than a century, from studies of their ecology in extreme aridland environments to investigations of their evolutionary origins and the mounting challenges to their persistence under human pressures. Yet, few quantitative syntheses have examined their history, diversity, and conservation. We compiled occurrence records for North American freshwater fishes and intersected them with the boundaries of the Baja California, Great Basin, Mojave, Sonoran, and Chihuahuan deserts. Integrating these data with phylogenetic relationships and conservation assessments, we: (1) generated an inventory of desert fish species and compared taxonomic composition among regions; (2) analyzed colonization, speciation, and extinction dynamics using phylogenetic comparative approaches; (3) identified levels of endemism and biodiversity hotspots across the regions; and (4) summarized conservation status, threats, and urgent needs. Our synthesis revealed a bimodal pattern of desert occupancy, with 118 species from 12 families primarily inhabiting desert habitats. Most belong to Leuciscidae, Cyprinodontidae, and Poeciliidae. Phylogenetic comparative analyses indicated that desert species are more clumped than expected under Brownian motion, with a median transition from non-desert to desert lineages occurring ~15 million years ago. Hidden-state speciation and extinction models further showed elevated net diversification rates in desert fishes, driven by increased speciation and extinction. Spatial analyses highlighted hotspots in the Cuatro Ciénegas valley, portions of the Conchos basin, and tributaries of the lower Rio Grande. More than half of desert fishes are threatened or endangered—disproportionately higher than for non-desert taxa—primarily due to water extraction, non-native species, agricultural and urban pollution, and intensifying drought. Together, these findings underscore both the evolutionary distinctiveness and precarious conservation status of desert fishes across North America.

ABSTRACT. The Devils Hole pupfish is an icon of desert fishes conservation and management in the United States. Nonetheless, after over 50 years of management, the wild population remains critically endangered due to its very small, nutrient-limited, and seiche-prone habitat in combination with its long-term small population size leading to reduced genetic health of the population. There remains a diabolical tension in understanding how the rapidly changing infernal environment of Devils Hole and the fiendishly low genetic diversity of this species are impacting its long-term prospects of survival. Here we directly assess the genetic health of this species by constructing the first de novo genome assembly and sequencing 186 whole genomes of Death Valley pupfishes, including over 50 Devils Hole pupfish. We also reconstructed a historical timeline of genetic diversity from museum samples and sequenced embryos that prematurely died during development. We estimated genetic diversity in Devils Hole pupfish to be among the lowest measured in any wild species which has persisted at this low level since at least the 1940’s before the most intense periods of anthropogenic disturbance. The wild population contained about twice the genetic diversity of the Ash Meadows Fish Conservation Facility refuge population in 2020, despite annual introductions of wild fish to the refuge. We also show that the most inbred individuals in the population with approximately half of their DNA in runs of homozygosity inherited from a recent common ancestor due to inbreeding are 9 times more likely to die prematurely during embryonic development than individuals with only 10% in identical runs. Finally, in support of the drift barrier hypothesis, we estimate the mutation rate for the Devils Hole pupfish to be 2 times higher than other fishes, 1.16 x 10-8 per base pair per generation, and find evidence that the breakdown of DNA repair pathways in this species is driving higher rates. Our comprehensive analyses of genomic health in this species should provide a strong foundation for future management actions in addition to highlighting the ability of this iconic endangered species to provide insights into broader evolutionary theory.

ABSTRACT. 'The Jewel of the Gila' is a short film that describes the Loach Minnow in its extant habitats of Eastern Arizona. This film details the life history, morphology, habitat, conservation, and threats to the Loach Minnow using underwater videography and storytelling from several Arizona fisheries professionals. The creation of this film was funded by a DFC conservation grant. This film can be viewed on YouTube via this link: https://www.youtube.com/watch?v=JOrhCMuaz9g&t=305s

ABSTRACT. Gambusia nobilis is a federally Endangered species found across a fragmented distribution within the Pecos River Drainage of Texas and New Mexico. Drought, human water usage, and potential hybridization with the introduced congeneric G. affinis and G geiseri threaten species persistence. Therefore, a conservation genomics study was conducted to provide information about levels of standing variation and to characterize levels of hybridization and admixture. A total of 12 admixed individuals were found across 12 distinct geographic samples, with nearly half of those collected at Phantom Spring, which had receded into the cave mouth. Unsupervised clustering suggested hierarchical structure, with a primary K =3 and deep divergences were detected among samples grouped into the Leon Creek watershed, the Toyah Creek watershed, and water bodies within the Bitter Lake National Wildlife Refuge (F’ST = 0.55-0.76). Phylogenetic analyses showed three distinct clades corresponding to the identified groups, with split times estimated to be in the last 50,000 years. Subsequent analyses detected a number of phenotypic differences among the three groups, including male color pattern in life and number of caudal-fin rays in both sexes. Taken as a whole, the data indicated that there are three distinct evolutionary units (species) present that likely require individualized conservation planning.

ABSTRACT. Texas Parks and Wildlife Department (TPWD) continues to advance a wide range of research and management initiatives focused on understanding, conserving, and restoring arid aquatic ecosystems across Texas. This presentation provides an integrated update from TPWD’s water and aquatic resource conservation and management initiatives, highlighting ongoing projects that address hydrologic alteration, groundwater-surface water interactions, spring and riverine ecosystem monitoring, and habitat restoration for native and imperiled fishes. Key topics will include updates on current research, monitoring, and conservation initiatives addressing aquatic ecosystems and water resources across Texas. In addition, a state-wide overview will summarize current water resource conditions, including drought status, surface- and groundwater trends, and recent policy or infrastructure developments influencing aquatic habitats. Collectively, these updates reflect TPWD’s expanding efforts to integrate ecological science with water management and to promote interagency collaboration to sustain Texas’s diverse desert and spring-dependent fishes under changing hydrologic and climatic conditions.

ABSTRACT. In this presentation we provide an overview of contemporary understanding of the ecohydrogeology of springs. Spring ecosystems develop where groundwater reaches the planetary surface, on land and under water. Springs are patchily distributed but abundant, perhaps with 20 million on Earth, and are distinctively individualistic ecosystems that provide the baseflow of most rivers in non-glaciated landscapes. Despite their generally small size, springs often support elevated within-site biodiversity of listed, endemic, rare, and poorly known taxa, as well as many undescribed lineages, adding substantially to regional gamma-diversity. Although springs account for less than 0.001% of terrestrial landscapes in the USA they support approximately 15% of the nation’s endangered species. Preliminarily, we documented more than 330 species of springs-dependent aquatic and riparian macro-taxa in the Colorado River basin in the seven southwestern basin states. Springs function as keystone ecosystems – often isolated habitat patches that are highly ecologically interactive as keystone ecosystems, supporting complex intrinsic assemblages as well as a great many upland species. In addition to their ecological significance, springs are cultural hotspots, holding deep significance for indigenous and dominant societies, and globally providing hundreds of billions of dollars in essential goods and services to billions of people worldwide. Despite their obvious significance and the well-studied field of groundwater hydrogeology, the characteristics, processes, and roles of spring ecosystems remain egregiously neglected and lack adequate stewardship and protection policies. Springs are threatened everywhere by groundwater withdrawal, under-informed land use practices, and climate change and, as throughout the world, the biota and conservation status of most North American springs remains largely unknown. Analysis of several thousand springs in the Basin and Range province of Nevada (USA’s driest state) revealed that >85% of springs there are impaired, more than two thirds of them seriously so. Declines in springs discharge align with recent findings on the dramatic depletion of groundwater levels across the nation over the past century. Although monitoring data are rare, analyses of long-term USGS streamflow data shows that 56% of gauged springs across the country, and nearly all large springs in the southwestern USA, have significantly declined in discharge over the past several decades. For example, central Arizona’s Del Rio Springs are the headwaters of the Wild and Scenic Verde River, but mean annual discharge decreased from 57 to <1 L/sec from 1996-2024 due to unregulated groundwater pumping of the Big Chino Aquifer and failing infiltration due to climate change. Declines in springs discharge have direct impacts on stream discharge and the diverse biota supported in these groundwater-fed habitats. From 2008-2022 Verde River baseflow decreased by 16% compared to 1993-2007. Only three of the 13 native fish species populations (including two listed species) remain in the middle reaches of that river. Now, as throughout our evolutionary history, springs serve as critical habitat for humanity, and their socio-ecological importance is increasing as current population and climate trends continue, not only in arid and semi-arid regions, but globally. On-going groundwater exploitation and climate warming are reducing infiltration and, consequently springs discharge and populations of the biota they support. The springs biome is everywhere undergoing a profound but largely ignored biodiversity crisis, one that warrants significant scientific, public, and governmental attention and action. Although the loss of springs is a dire issue, multiple restoration projects have demonstrated that, if the supporting aquifer is relatively intact, spring ecosystems can be relatively easily rehabilitated and managed to better balance ecological and economic values.

ABSTRACT. Springs are among the most biologically diverse and socio-ecologically significant ecosystems on Earth. Despite their small footprint, they serve as global hotspots of biodiversity, often supporting endemic species found nowhere else. Yet despite their extraordinary importance, springs have long been overlooked in conservation planning and policy. At the recent 2025 IUCN World Conservation Congress, Motion 016 on the conservation of springs was adopted as a formal resolution, marking an important milestone in bringing international recognition, visibility, and coordination to these critical ecosystems. Building from this success, we are spearheading two complementary global initiatives to advance science, policy, and action to safeguard springs. The IUCN Springs Task Force will serve as a scientific and policy working group under the IUCN framework, dedicated to identifying research priorities, establishing global guidelines for springs protection, and promoting policy mechanisms that formally recognize springs as essential ecosystems. In parallel, the Global Springs Alliance will unite Indigenous people and local communities, land managers, funders, and conservation practitioners to mobilize investments and coordinated actions that promote on-the-ground restoration, monitoring, and protection of springs across regions and continents. At this year’s Desert Fishes Council meeting, we will present the vision, scope, and structure of these initiatives, invite participation from the springs and freshwater science community, and outline next steps for collaborative research and conservation action. Together, these efforts aim to build a global movement that ensures the long-term protection of springs and the extraordinary life they sustain.

ABSTRACT. Springs are biodiversity hotspots that harbor unique assemblages of endemic species, sustain river baseflows, and support surrounding terrestrial ecosystems. They also hold economic, cultural, and spiritual significance for people worldwide. Despite their importance, spring ecosystems face mounting threats from groundwater extraction, land development, invasive species, pollution, and climate change. While numerous local and regional initiatives address spring conservation, a coordinated global effort remains absent. Momentum is growing to change this. Recently, a coalition of conservation NGOs and zoos advanced a motion at the IUCN World Conservation Congress calling for urgent action to safeguard neglected spring ecosystems. Building on this momentum, there is increasing interest in developing a global alliance dedicated to spring conservation—an alliance that could foster collaboration, close knowledge gaps, standardize research approaches, influence policy, and amplify awareness. This roundtable will invite Desert Fishes Council participants to share their experiences, insights, and ideas toward shaping such an initiative. Discussion will focus on identifying critical conservation challenges, exploring strategies for capacity building, and outlining priorities for a coordinated global effort to ensure the persistence of springs and their unique biota.

ABSTRACT. Animals continuously shed DNA into their environment, creating trace genetic material known as environmental DNA (eDNA). This material can be used to non-destructively infer the presence and relative abundance of organisms through molecular detection methods such as quantitative PCR (qPCR) and metabarcoding. Here, we describe experiments designed to optimize eDNA sampling efficiency using a combined qPCR–metabarcoding approach. Fieldwork was conducted at the headwaters of the Amargosa River in Nevada, within the former 7J Ranch (Atwood Preserve). We tested a range of sampling variables, including filter pore sizes (0.45, 0.7, 1.2, and 5 µm), filter materials (polyethersulfone and glass fiber), and water column depth (surface neuston vs. midwater). Most experiments were conducted at Dace Spring, a high-quality spring believed to host only the endemic speckled dace (Rhinichthys osculus nevadensis). Results indicated that while finer pore-sized filters produced higher total DNA yields, larger pore sizes preferentially enriched for target fish DNA despite lower overall concentrations. Neuston samples consistently yielded less DNA, and qPCR detection rates of fish were correspondingly lower, using an adaptation of MiFish 12S rRNA gene primers. Our assays confirmed the absence of invasive mosquitofish (Gambusia affinis) and the presence of pure speckled dace in Dace Spring, while also verifying a cryptic population of dace in a small, previously unconfirmed spring. Additionally, metabarcoding revealed Micropterus salmoides (largemouth bass) in a nearby farm pond, though its DNA signal was absent in the pond’s anoxic hypolimnion. These findings demonstrate how eDNA sampling design, particularly filter selection and water-layer targeting can critically influence detection outcomes in desert spring ecosystems.

ABSTRACT. Protection of the desert pupfish (Cyprinodon eremus) in the Sonoyta River, as an educational project at the Sonoyta State High School. In response to this need, the conservation project emerged, creating a network of refuges (ponds) for the protection, recovery, and reintroduction of native freshwater species of the Sonoyta River. These refuges are recognized as ex situ conservation sites. The decision to build a pond at the Sonoyta COBACH was based on its permanent protection, its location in the species' natural range (near the Sonoyta River), and its role as an educational space to raise awareness about the value of these native species. Initially, the pond housed three endemic species: the desert pupfish (C. eremus), the green-bellied turtle (Agosia chrysogaster), and the sandhill turtle (Kinosternon sonorense); however, the only species that survived over the years was the desert pupfish. The project aims to ensure its protection, conservation, and publicity, so that it is known, respected, and creates pride in the community. It demonstrates its sustainability, as for more than 17 years, its population has remained stable and increased considerably without undergoing any morphological or apparent genetic changes. The project is a clear example that the only way to transform society is through education.

ABSTRACT. For the last 30 years three Extinct in the Wild Mexican pupfish species (Cyprinodon alvarezi, C. longidorsalis and C. veronicae) have existed in precariously small numbers, cared for in a small number of dedicated ex situ facilities including zoos and aquariums, outside of México. These three species, once occurred in relatively close proximity in the Nuevo León State in México, in small spring habitats, and suffered the similar threats that resulted in their extinction from the wild by the early- to mid-1990s. Following the species conservation cycle implemented by the IUCN/SSC in recent years, efforts in Mexico to address the freshwater fish extinction crisis have intensified, including the development of action plans aimed at critically endangered species as well as the development of strategies for the return of species kept in captivity to the wild. It is within this framework that with the leadership of the Zoological Society of London, this proposal was developed, which seeks to revitalize the ex situ populations of each species to guard against extinction, to establish ex situ populations in Mexico, as well as provide numbers of pupfish for upcoming planned releases over the next five years, establishing the first wild populations for each species in nearly three decades. As part of the activities carried out to date, captive populations have increased and new populations have been established in other aquariums such as San Antonio Zoo and Vienna. A facility has also been established at the Inbursa Aquarium in Mexico City for the maintenance and reproduction of these species in Mexico and we are awaiting permits for their importation. A hydrogeological and hydrological evaluation was also carried out to see the feasibility of recovering the water flows necessary for habitat restoration. To this end, Environmental Systems (HS) were defined that delimit each spring of interest, the behavior of the system was analyzed through hydrography, geological units, aquifers, climatology (historical records of 40 years) and elaboration of hydrological balances. Based on this information, participatory planning work has been carried out with the ejidos of the region to establish the necessary agreements for the reintroduction of the species. Preliminary results show that there is the possibility of establishing populations in situ, in addition to working on the maintenance and recovery of some flows, but the most important thing has been the positive response of the ejidos, as well as their interest in the return of the species that were once part of their natural heritage and that the elderly people of the community still remember. We are clear that there is still a lot to do before we are able to return these species to the wild, but we believe that we will be able to reach our goal of recovering some in the next five years.

ABSTRACT. Small desert streams that are tributaries to larger rivers can be important habitats. In highly altered river basins, like the Colorado River, unregulated tributaries can provide important spawning and rearing habitat for native fishes. While there are quite a few tributaries to the Colorado River within the Grand Canyon, such as the Little Colorado River, Havasu Creek, Bright Angel Creek, etc. … there is only one tributary within Glen Canyon, the Paria River. The Paria river is approximately 153 km in length, with an average flow of 0.79 m3/s (minimum 0.028 and maximum of 460 m3/s) and is known for its muddy and turbid water. The Paria River is an important source of sediment within the Colorado River downstream of Glen Canyon Dam, and it is not known for its fishes. While the Colorado River and many of its tributaries have monitoring programs in place, none occur on the Paria River. In the spring of 2025 we placed two remote PIT tag antennas in the Paria River for two months and detected 679 unique fishes during that time: 587 Flannelmouth Sucker, 8 Bluehead Sucker, 1 Rainbow Trout and 83 unassigned fish. The importance of the Paria River to populations of native fishes within Glen Canyon and Grand Canyon is unknown at this time.

Los pequeños arroyos del desierto, afluentes de ríos más grandes, pueden constituir hábitats importantes. En cuencas fluviales alteradas, como la del río Colorado, afluentes que no son regulados pueden proporcionar un hábitat importante para el desove y la crianza de peces nativos. Mientras dentro del Gran Cañón, en el Río Colorado, existen bastantes afluentes, como el río Little Colorado, el arroyo Havasu y el arroyo Bright Angel, solo se encuentra un afluente dentro del Cañón Glen: el río Paria. Este río se extiende aproximadamente 153 km en longitud, con un caudal promedio de 0,79 m³/s (mínimo de 0,028 y máximo de 460 m³/s) y es conocido por sus aguas turbias. El río Paria es una fuente importante de sedimentos dentro del río Colorado aguas abajo de la presa del Cañón Glen, y no es conocido por su pesca. El río Colorado y muchos de sus afluentes cuentan con programas de monitoreo, pero ninguno  se encuentra en el río Paria. En la primavera de 2025, instalamos dos "PIT" antenas de etiquetas remotas en el río Paria durante dos meses y detectamos 679 peces únicos: 587 matalotes de boca de franela, 8 matalotes de cabeza azul, 1 trucha arcoíris y 83 peces sin asignar. Actualmente, se desconoce la importancia del río Paria para las poblaciones de peces nativos del Cañón de Glen y el Gran Cañón.

ABSTRACT. New standards for digital data about specimen- and occurrence-related data, which are rapidly being adopted by the museum collections community, are relevant far beyond collections. Extended Specimens and FAIR (Findable, Accessible, Interoperable, and Reusable) are concepts based on the broad use of Digital  Persistent Identifiers (PIDs) to implement linkages across the internet to diverse data related to both specimens and geography, timing, and other details of species occurrence. These new standards provide easy ways to link to original documentation deposited along with specimens (imagery of live specimens, habitats, collectors, fieldnotes, etc.) as well as linkages to subsequent derivatives from specimens (e.g. data sets, xrays, CT scans, tissue samples, sequences, publications) even if those derivatives are deposited or published on diverse digital platforms (e.g. Genbank, BOLD, Morphobase). Such linkages greatly increase the value of specimens and the data associated with them and ensure that that value persists into the future, avoiding the linkage rot (broken links) typical of many web-based publications.

While it can take immense effort to compile retrospectively, publish, and link resources related to legacy specimens, effort is often worth the investment. As the value of these new protocols is now widely recognized in the global collections world, many collections are starting to obtain significant funding to allow such improvements. If these standards are recognized and implemented early in the design phase of sampling protocols for new projects, linkages across all derivatives can be immensely facilitated, as can open data publication (which is starting to require at least the primary basics of these new protocols.

We encourage early adoption of these standards for all biological research (whether specimens are preserved or not) as a way to assure that all organism collections are quickly made available to the rapidly increasing communities of researchers and managers striving to save endangered species and implement sustainable management practices. We describe our experiences working with legacy specimens that exemplify the obstacles confronted when such protocols are not used, often resulting in specimen occurrence data never being published or used in future research. Historical organismal occurrence data are critical for establishing baselines for any kind of attempts to implement susstainable management, and ideally all data ever collected should be made openly and freely available in readily usable formats, Here we provide links to key resources to help people familiarize themselves with the benefits and processes related to Extended Specimens and FAIR (Findable, Accessible, Interoperable, and Reusable) data to help assure that their efforts produce lasting ability to support these goals.

ABSTRACT. Independence Valley speckled dace, Rhinichthys osculus lethoporus, face numerous threats to their existence, including habitat degradation, ground water extraction, and climate change. Developing and evaluating optimal sampling designs to assess the status of R. o. lethoporus is critical to ensure conservation and recovery actions are effective. This is particularly important in arid desert environments, where systems are often difficult to sample and can exhibit high environmental heterogeneity, hindering accurate species status assessments. Addressing these challenges requires sampling designs that balance statistical precision with logistical feasibility and cost constraints. Such optimized approaches are particularly critical for monitoring rare desert aquatic species, where traditional intensive sampling may be prohibitively expensive or logistically impractical. In this study, we assessed the current population status for R. o. lethoporus to better understand population dynamics within the Independence Valley Warm Springs system in northeastern Nevada. We sampled dace using minnow traps at multiple locations within the wetland complex over two years and estimated abundance with the Huggins closed capture model. Each site was paired with environmental DNA (eDNA) samples, records of non-native species presence, and standard water chemistry parameters. Preliminary results suggest that eDNA may be useful for assessing the status of R. o. lethoporus, and non-native species presence may negatively influence dace occupancy within the Independence Valley Warm Springs system.

ABSTRACT. Spring-fed systems of the US Great Basin are home to an extraordinary diversity of endemic and/or threatened aquatic organisms — animals whose fortunes are tied to societal and hydrologic variables and competition/predation from invasive species. Aquatic organisms continuously shed DNA into their surroundings. This “environmental DNA (eDNA)” is detectable with exquisite sensitivity through quantitative Polymerase Chain Reaction (qPCR) and metabarcoding. Here we report on optimized sampling and DNA extraction protocols (e.g. high-volume filtration) and validation of published and custom-designed molecular probes (qPCR primer sets) utilizing mitogenome targets for a range of endemic and invasive species in spring-fed environments of the Mojave Desert.

Published Metabarcoding fish primers (e.g. MiFish (12S rRNA gene)) were used to quantitatively document an ongoing mosquitofish (Gambusia affinis) invasion at the Shoshone pupfish refugium (Cyprinodon nevadensis shoshone) in Shoshone, CA. This sequence-based assay was also used to verify known and cryptic populations of Amargosa speckled dace (Rhinichthys osculus navadensis) in Amargosa River headwater springs and explore diversity of endemic and invasive fish assemblages on the Muddy and Virgin Rivers in Nevada. The river work established many species, but some highlights include the detection of strong populations of Virgin River Chub (Gila seminuda) in the Muddy and Virgin Rivers and chub, desert sucker (Catostomus clarkii) and speckled dace (Rinichthys osculus) in the Virgin. A rogue’s gallery of invasives was also present in both, especially the Virgin River below Mesquite, NV, where red shiner (Cyprinella lutrensis)), common carp (Cyprinus carpio), channel catfish (Ictalurus punctatus), largemouth bass (Micropterus salmoides) and green sunfish (Lepomis cyanellus) dominated. Conversely, blue tilapia (Oreochromis aureus), which have been eradicated from the Muddy and have been detected sporadically in the middle Virgin, were not detected, although they were easily detected in the Las Vegas Wash.

Specialty assays developed by the lab included a sensitive and specific qPCR assay for endangered Moapa dace (Moapa coriacea) and new qCPR and metabarcoding primers for super-invasive red swamp crayfish (Procambarus clarkii), which have been tested at Ash Meadows, the largest oasis in the Mojave. Other work includes eDNA surveillance of an Australian redclaw crayfish invasion (Cherax quadricarinatus) at ponds associated with the Las Vegas Wash and a study of the microbiome of Devils Hole pupfish (Cyprinodon diabolis). This work illustrated that captive pupfish microbiomes were dependent upon aquaculture techniques, with only recirculating tanks (vs. flow-through) establishing populations of a commensal bacterium (Cetobacterium spp.) which is thought to assist the fish with ethanol metabolism, an adaptation of the fish for survival under low-dissolved oxygen.

ABSTRACT. The Monterrey Metropolitan Zone (MMZ) in the state of Nuevo León faces a severe water crisis that impacts its water bodies. These ecosystems host freshwater fish that provide key ecosystem services, but their diversity and functionality are threatened by habitat alteration and the introduction of exotic species. Given the lack of information, the study proposes using the functional diversity approach, which examines the aspects of the ecological roles of species in their environment, and quantify the traits of the fish and evaluate their ecological roles in this anthropized environment. This approach is useful for understanding the response of communities to disturbances, predicting invasions, and designing conservation strategies. It is hypothesized that there are differences in ecological functionalities among the sites within the MMZ. The main objective is to evaluate this functional ecology based on the characterization of taxonomy, geometric morphometric analysis, functional attributes, and dispersion. Understanding the diversity and ecological functions of fishes in the MMZ is essential to assess the services they provide to ecosystems and to establishing the health of the regions waters bodies.