Various Topics


  • Evaluating Genetic Diversity and Distinctiveness of Northern and Southern Idaho Ground Squirrel Populations Using Adaptive and Neutral Loci*
  • Molly J. Garrett; Soraia Barbosa; Kimberly R. Andrews; Amanda R. Goldberg; Digpal S. Gour; Paul A. Hohenlohe; Courtney J. Conway; Lisette P. Waits
    The endemic northern Idaho ground squirrel (Urocitellus brunneus, hereafter NIDGS) and southern Idaho ground squirrel (Urocitellus endemicus, hereafter SIDGS) have recently been distinguished as separate species. These two species are morphologically distinct, occupy different habitat types, and do not interbreed. NIDGS is a federally listed endangered species and SIDGS is a state listed species of conservation concern. However, recent modeling efforts have indicated SIDGS may be more susceptible to future habitat loss and fragmentation than NIDGS. Previous work on these species has suggested population persistence may be highly dependent on locally adapted genotypes. Recent work from our research group used genomic methods to provide novel information on neutral and adaptive genetic diversity and differentiation within and between populations of NIDGS and SIDGS. Genetic samples were collected from 304 Idaho ground squirrels using buccal swabs and were used for Restriction Site Associated DNA Sequencing (RADSeq) to identify 7,197 single nucleotide polymorphism (SNP) loci. A clear genetic separation between NIDGS and SIDGS for both adaptive and neutral loci was observed, with elevation being the main variable explaining adaptive differences. However, this study evaluated NIDGS and SIDGS together, limiting the scope of this research to broad-scale variation. Furthermore, this study used samples collected from a limited range of the geographic distribution of each species. To further understand which factors are influencing differentiation and connectivity at smaller scales and to estimate key demographic variables like effective population size, we plan to develop a genotyping panel from neutral and adaptive SNPs. This SNP panel will then be used to genotype archived samples of both species to expand the geographic coverage of this genetic dataset. Analyzing these species separately with increased sample sizes will provide more powerful approaches to understand gene flow, local adaption, and metapopulation dynamics in each species.

  • Genetic Rescue Or Genetic Swamping: A Long-Term Assessment of a Population Augmentation*
  • Tiffanie B. Atherton; Clayton K. Nielsen; Edward J. Heist
    Population augmentations are sometimes considered when managing populations at risk of extirpation. The eastern woodrat (Neotoma floridana) is broadly distributed throughout the southeastern U.S., with a northern edge of the distribution in southern Illinois. Following a massive reduction in range size throughout the 1900s, the eastern woodrat was added to Illinois’ endangered species list in 1977. Field surveys uncovered 3 remnant populations including one at LaRue Pine Hills (LPH) which was augmented in 2004-05 by woodrats originating from genetically distinct populations from the Ozarks (Missouri and Arkansas). The goal of our study is to determine the current conservation status of the eastern woodrat in southern Illinois and to what extent the current population are descendants of translocated animals. Our objectives are to: (1) estimate effective population sizes (Ne) of the LPH remnant population and the current population; (2) determine what fraction of the genes in the current population originated from the remnant population; and (3) determine what fraction of the remnant mitochondrial DNA has been preserved in the current population. All 3 objectives use LPH remnant woodrat samples (n = 40) and 2019 field samples (n = 83). We will assess the changes in Ne using 12 microsatellite loci and the program LDNe to estimate linkage disequilibrium. NEESTIMATOR will be used to correct for bias of single sample estimators. To determine what fraction of remnant genes persist, we will use the Bayesian clustering program STRUCTURE, which assigns individual genotypes to K populations. Cytochrome b haplotype network trees constructed using POPART will be used to evaluate distributions of remnant and introduced haplotypes. Conservation implications include a re-assessment of the LPH population following an augmentation in accordance with Objective 3 of Illinois’ Eastern Woodrat Recovery Plan, which aims to remove the eastern woodrat from state endangered status.

  • Validating the Use of a Handheld Meter for Measuring a Plasma Metabolite, Triglyceride, in the Field
  • Christopher Roelandt; Jill Witt, PhD.; Amber Roth, PhD.
    Plasma metabolite concentration analyses have been shown to be effective in predicting change in body mass and are useful as a measurement of body condition in birds. One such plasma metabolite, triglyceride (TRIG), has been shown particularly capable of predicting when birds are either in a state of fattening or fasting. These predictions can be a useful tool for wildlife and land managers interested in assessing quality of habitat as measured by its ability to provide feeding resources to individual birds using that habitat. Plasma sample collection in a field setting can be challenging and methods aimed at reducing these challenges may help to expand their use in the field. I explored the use of a small handheld meter, CardioChek PA analyzer, for measuring TRIG concentrations as a means to reduce challenges that are associated with the use of plasma metabolites. Following the CardioChek PA manufacturer’s guidelines, I tested results of TRIG against results of the same sample completed in a laboratory analysis to determine the validity of using a handheld meter in the field. I found that the handheld meter was precise in its results but not able to accurately measure TRIG in the field, possibly due to the interactions with the extreme environmental conditions in the field. I recommend further research into the limitations of this handheld meter and developing methods to reduce the effects of light, temperature, and humidity in the field.

  • Carnivore Dynamics Within the Scavenging Community Across the Central Appalachian Mountains, Virginia*
  • Darby McPhail; Robert Alonso; David McNitt; Brogan Holcombe; David Lugo; Marcella J. Kelly
    Scavenging on carrion by wildlife has ecosystem level effects, both abiotically through nutrient cycling processes and biotically through impacting population dynamics, yet there are relatively few studies on scavenging ecology, even for large predators. For example, we lack information on which predator species facultatively scavenge, and on predator behavior at carcasses. As part of the Virginia Appalachian Carnivore Study, we investigated scavenging behavior and dynamics of the three largest predators (Lynx rufus, Ursus americanus, and Canis latrans) in the Central Appalachian Mountains. From 2017 to 2020, we set up remote cameras at 60 sites directed towards deer (Odocoileus viginianus) carcasses that we obtained from vehicle collisions. Carcass sites were distributed opportunistically across all seasons a minimum of 10 km apart to avoid multiple carcasses within a single animal’s home range in one particular season. We analyzed species presence, latency to detection of the carcass, order of scavenging, time spent foraging, and examined dominance amongst guild members both when bears are present and absent (i.e. during hibernation). We found that all three top predators, and multiple small predators, found and scavenged on carcasses. From May- December, black bears were most frequently the first to find the carcasses when found by all three species, bobcats remained in the carcass vicinity the longest, while coyotes found more of the carcasses but appeared to exhibit brief yet frequent visits. From January-April, bobcats and coyotes were equally the first to find carcasses, but took longer to find them, and exhibited similar eating strategies as shown from May-December. We also found multiple carnivores feeding simultaneously with the exception of bears, which always fed alone. This preliminary analysis will aid in future research on mammalian predator scavenging ecology within multifaceted carnivore communities.

  • Contrasting Effects of Native and Invasive Bivalves on Biofilm Production*
  • Brianna Gibbons; Kiersten Youngquist; Andrea Darracq; Wendell Haag
    One way freshwater mussels modify aquatic ecosystems is through biodeposition, which ultimately influences biofilm growth. Biofilms play an important role in nutrient cycling within aquatic ecosystems and provide a food resource to aquatic organisms. Of 300 known species of North American freshwater mussels, 202 are listed as species of concern. Many of these declines are linked to invasions of other bivalves into aquatic systems, such zebra mussels (Dreissena polymorpha) and Asian clams (Corbicula fluminea). Decreases in freshwater mussels and increases in invasive bivalves globally may influence biofilms and ultimately nutrient cycling within aquatic ecosystems. The objective of our experiment was to determine if biofilm production is influenced by freshwater mussels or Asian clams. Our experiment consisted of a 2 x 3 factorial design with Asian clams or native mussels (Amblema plicata and Plectomerus dombeyanus) stocked into 0.6 m2 flow-through mesocosms at different densities (low, medium, or high). We placed four ceramic tiles within each tank and quantified the biofilm production on a single tile from each tank every two weeks. Biofilm production increased over time, but there was no effect of treatment through 6 weeks. However, by week 8 the native mussel treatments had 2.4 – 3.6 times more biofilm produced compared to the control. The Asian clam treatments did not differ from the control. Our results support previous studies demonstrating a relationship between native mussels and biofilm production. However, we did not observe a similar relationship between Asian clams and biofilm production. In the SE USA, Asian clams are often the dominant bivalve in aquatic systems where native mussels would have once been prevalent. Consequently, it is possible the loss of native mussels and invasion of Asian clams could have ecosystem level affects via reductions in biofilm production.

  • Harvesting and Sharing of Wild Meat in Texas, United States of America
  • Shane Patrick Mahoney
    Recreational hunting participation in the US and Canada has decreased significantly over the last several decades, yet public support for these activities remains high in both countries. To date, there has been very little research to determine the reasons for this persistent trend. However, it has been theorized that this support is garnered through regular positive interactions and activities that connect hunters with the broader public. One such activity is the sharing of wild harvested meat. Situated within the larger Wild Harvest Initiative® this research project was undertaken to determine the extent of these sharing practices as well as hunters’ associated underlying motivations. Using Texas as a case study, this research employed a quantitative research approach in which a random sample of Texan hunters were sent an online survey questionnaire regarding their hunting and wild meat sharing habits. A total of 2,735 completed questionnaires were used in the final analysis. The survey revealed that nearly all successful hunters (97.7%) share their wild harvested meat; on average sharing 41.3% of their harvest. While the findings revealed interesting demographic differences in terms of motivations for sharing, respondents primarily reported being motivated to share because they possessed more than they could consume in their household and they wanted to help family and friends with food stocks. The findings of this survey clearly demonstrate that the benefits of wild recreationally harvested meat in Texas extend well beyond the harvesters themselves to positively impact many others. The magnitude of wild meat sharing in Texas and the motivations for these activities reflect a tradition that serves to build and strengthen community networks, lending credence to the theory that these activities help foster broad support for hunting activities within the US and Canada. Additional surveys planned for other jurisdictions will serve to expand and strengthen these findings.

  • Surgically Implanting River Otters with Intra-Abdominal Radiotransmitters Using Reversible Non-Dea Scheduled Drugs
  • Tatiana E. Gettelman; Joseph M. Scimeca; Clayton K. Nielsen; Eric M. Schauber
    For radiotelemetry studies, river otters (Lontra canadensis) are often radiomarked with surgically implanted intra-abdominal transmitters as they are ill-suited for traditional radiocollars. However, availability of an approved surgery suite can be locally limited and transport of a river otter from the trapping location increases stress to the animal. Furthermore, constraints exist for using scheduled drugs in a field setting due to increasingly strict U.S. Drug Enforcement Agency and university Institutional Animal Care and Use Committee regulations. To address these challenges, we developed a protocol for immobilization and field surgery of river otters with non-scheduled drugs. We surgically implanted 21 river otters with intra-abdominal radiotransmitters (42 g) in southern Illinois during November 2018-March 2020 and recorded 1 mortality during surgery and 1 probable capture myopathy mortality 4 days post-surgery. River otter weights were estimated and initial sedation was achieved with a combined intramuscular injection of dexmedetomidine (0.045-0.077 mg/kg) and nalbuphine (0.818-1.543 mg/kg) and maintained with isoflurane (1-4%) via a portable vaporizer. Surgery was performed while maintaining aseptic technique in a 3×3 m tent within 200 m of capture sites. Penicillin G benzathine (1 mL) and either meloxicam (0.5 mL) or carprofen (4 mg/kg) were administered prior to the first incision and oxygen was provided continuously during sedation. River otters were reversed with atipamezole (10 mg/mg dexmedetomidine given) immediately after surgery and released as soon as a full recovery was achieved, typically 0.5-1 hr post-surgery. No signs of infection or surgery site complications were detected, and all river otters were monitored until mortality or transmitter failure. This method for radiomarking river otters minimized stress and handling time without compromising animal health and provided a less restricted source of chemical immobilization.

  • Assessing Wild Turkey Occupancy Using Autonomous Recording Units and Package Monitor*
  • Janelle Ostroski; Jay Cantrell; Charles Ruth; Beth Ross
    Wild turkey is a highly popular game species harvested primarily during the reproductive season, which has driven substantial efforts to understand patterns of springtime habitat use. Gobbling activity and associated habitat selection has been increasingly assessed through ARU deployment, yet post hoc processing of audio data has been time-intensive particularly due to false detection rates and streamlining this process would benefit future research. Gobbling activity has been studied in the South Carolina coastal plain, but data for the upstate is lacking. Our goals are to assess spring gobbler occupancy patterns using ARU data from 2019-2021 in conjunction with an alternative acoustic template finder monitoR. In 2019, we deployed 38 ARUs throughout upstate SC and collected daily 3-hour recordings from March 1 to May 30. We are using monitoR to automatically scan recordings for gobbles and incorporate detection data into single-season occupancy models using a suite of habitat covariates (e.g., distance to water, burn age of stand). We expect MonitoR to return fewer false positives than comparable software which will allow for more precise estimates of detection and spatio-temporal trends in habitat use. Our results can hopefully help direct habitat management decisions and be leveraged by upstate hunters to optimize outing quality and harvest success.

  • Hunter Behavior and Harvest Success: The Effect of Hunter Movement and Site Selection on Observation Rate of White-Tailed Deer*
  • Alyssa Meier
    Hunting is the primary tool for population control for many ungulate species across the United States, including white-tailed deer (Odocoileus virginianus). Previous research has focused primarily on the effects of hunting on prey behavior while neglecting the potential effects hunter behavior has on the probability of harvest success. Hunters make numerous active decisions while hunting that affect their probability of success, such as where to hunt on the landscape and hunting method (i.e. ground-blind, tree-stand, still hunting). Because wildlife managers rely on hunting for population control, it is important to understand and quantify hunter behavior to more confidently meet management goals. In this study, I will examine hunter movement patterns and site selection and assess how these parameters affect hunter observation rate of white-tailed deer. The information provided by my research will help educate hunters on becoming more effective and efficient, and inform wildlife managers on methods to more reliably meet harvest quotas.

  • The Effects of Prescribed Burns on White- Tailed Deer in the Pine Barrens of New Jersey*
  • Jenna L. Walker; Catherine A. Tredick
    Prescribed burns are commonly used as a forest management technique and provide various benefits to forest ecosystems. These include reducing the probability of wildfires, managing invasive species or improving wildlife habitat. Stockton University, located within the Pine Barrens of Southern New Jersey, has adopted a ten-year forest plan to be carried out on 1,522.80 acres of land, including the use of prescribed burns. To better understand the impacts of these prescribed burns on wildlife, the activity levels of white- tailed deer (Odocoileus virginianus) were analyzed both before and after four different prescribed burns on campus. We used motion-sensor wildlife cameras at four different sites to capture white- tailed deer activity. Two cameras were located directly within areas that underwent burning, while two additional cameras located within nearby, unburned forest areas were used as controls for comparison. Overall, we assessed deer activity at regular intervals post- burn and subsequently compared to the activity levels prior to burning. We will present results of changes in deer activity pre- and post- burn to determine how prescribed burning affects white- tailed deer activity in a pine- oak forest ecosystem.

  • Management of Native Wildlife and Habitat on Private Lands in Texas*
  • Cheyenne T. Holt; Thomas W. Schwertner; Heather Mathewson; Darrel Murray
    The majority of Texas lands are privately owned. This proves challenging for many aspects of conservation in the state. Landowners play a crucial role in the effort to protect native integrity of private Texas land. There are many private landowners interested in conservation, but don’t know how to properly manage for native wildlife and habitat. We are working with local landowners to improve the integrity of native wildlife and habitat on their property. We are also developing their land with the intention to create educational opportunities for other landowners. We will continuously assess and monitor existing biodiversity, restore ecosystem function, enhance native biodiversity, evaluate new management practices, and provide outreach, demonstration, education, and interpretation opportunities on their property. These goals will be achieved by conducting various surveys, developing a rotational burn plan, eradicating invasive plant species and seeding with native species, installing various bird boxes, and designing a website that will highlight these practices. We developed our goals and management practices into a 5-year management plan for the landowners. An interpretive plan will also be developed and will provide landowner outreach events, a public field day, an interactive and educational nature trail, as well as launching a website that highlights the management practices implemented on the property. We provided these local landowners with the opportunity to promote native wildlife on their land and benefit from the management practices we implemented. This project continues to present a unique opportunity to educate other private landowners with ways to benefit and support native wildlife and habitat on their properties. Projects and education opportunities such as this may be crucial for the future of successful conservation of private lands.

  • A Conservation and Economic Analysis of Birdwatchers Versus Non-Birdwatchers in Pennsylvania*
  • Ty Sharrow; Valorie Titus
    In recent years due to decreased hunting participation along with the growing need for conservation action, there is an increasing desire for supplemental funding from alternative sources towards environmental protection. Birdwatchers may serve as such a source. Before strategies for management and funding can be conceived, the economic impact that birders have, and what conservation attitudes they hold must be understood. Pennsylvania can serve as a case study to understand such a relationship. The results of this survey supports that Pennsylvania birders have a direct positive influence upon bird populations and existing conservation practices. It also shows the extent of how Pennsylvania birders engage in the economy concerning their outdoor recreational involvement.

  • The Future of Wildlife Conservation Funding: What Do College Students Think?
  • Lincoln R. Larson; Victoria Vayer; Kangjae J. Lee; M. Nils Peterson
    Funding for wildlife conservation in America has historically been fueled by contributions from hunters and anglers. Today, revenue generated by hunting and fishing license sales and equipment purchases (via federal excise taxes) continues to represent a critical funding source for state wildlife agencies. But as the population of active sportsmen and women across the county declines, the sustainability of conservation funding is uncertain. Agencies are therefore asking an increasingly urgent question: where will (and where should) future conservation funding come from? To help answer this question, our study focused on a population that will define the future of conservation: college students. From 2018-2020, we surveyed over 15,000 students at major public universities across 22 states. We found that just over 50% of the students were aware that hunting and fishing were primary sources of conservation funding. Non-hunters, non-natural science majors, and students from urban areas were more likely to believe conservation funding came from public tax dollars or park entrance fees. When asked to evaluate nine potential conservation funding options, students showed the strongest support for companies that profit from natural resource extraction (e.g., oil, gas) contributing a portion of their annual revenue to conservation (more than 80% supporting, 58% strongly supporting). Licenses sales for hunting and fishing were the second most popular alternative (80% supporting). More than 60% of students were also likely to support other conservation funding sources including state lottery proceeds and state sales taxes. Taxes associated with non-consumptive outdoor recreation equipment were the least popular option. Natural science majors displayed stronger support for nearly all funding options, but we observed few other differences among subgroups of students. Results suggest that college students, regardless of their demographic background, are likely to support innovative approaches and expansion of the traditional model of funding for wildlife conservation.

  • GPS Collar Based Evaluation of Sika Deer Management in Protected Areas of Hokkaido, Japan
  • Kohei Kobayashi; Tsuyoshi Yoshida; Rika Akamatsu
    Although many Asian nations and regions are facing the decline of deer species, Japan is an only Asian country where deer populations has drastically increased. Overabundant Sika deer (Cervus nippon) in protected areas is an emblematic ecological phenomena of Japan; however, main policy and management schemes of deer overabundant are still based on intensive doe harvesting outside of protected areas. No previous study attempted to prove an effectiveness of deer management based on harvesting mortality in/out of protected areas. We analyzed 100 GPS collared female deer at 10 capture survey sites of Hokkaido, the northernmost island of Japanese archipelago. We defined urban areas and wildlife refuges as protected area. We classified 100 deer into two population groups based on >50% or <50 % of GPS locations data in protected area, wherein groups were categorized “Protected Deer (PD) ” with > 50 % and “Hunted Deer (HD) ” with < 50%. The average ratio of protection area use by sika deer was 54%. We classified 62% deer as PD, and 38% as HD. We calculated harvesting mortality for each group. Harvesting mortality was 0% in PD, and 26.3% for HD. This result suggested that deer spending half a year in protected area was not affected by harvesting even the outside of protected area. We conclude that severe ecological and biodiversity impacts in protected areas of the study area are only possible to ameliorate through active managements of deer population inside the protected area.

  • Diet Analysis of Coyote Scat in South Carolina Through DNA Metabarcoding*
  • Jordan L. Youngmann; Stacey L. Lance; John C. Kilgo; Charles Ruth; Jay Cantrell; Gino J. D’Angelo
    Coyotes (Canis latrans) are generalist omnivores which consume a wide range of plants and animals. With their recent expansion into the Southeast, and potential impacts on endemic game and non-game species, there is considerable interest in what coyotes consume. Coyote diets have traditionally been assessed through simple visual identification of morphometric characteristics of food items within scat. This method can only broadly categorize prey and plant species and may not document the varied diet choices of coyotes due to digestion. However, through the recently developed technique of DNA metabarcoding, we hope to more fully explore the diet of coyotes. We will use fecal samples collected during the spring of 2020 and 2021 on secondary roads at 3 sites across South Carolina, USA, with the goal of 100 samples per site. We will design and optimize an array of genetic primers to detect species found within each fecal sample through DNA metabarcoding. Species of particular interest include white-tailed deer (Odocoileus virginianus), wild turkeys (Meleagris gallopavo), and other ground-nesting birds. Interestingly, there has been little documentation of coyote consumption of bird species and there is some concern that traditional diet analysis has failed to identify instances of predation. These data will provide a better understanding of coyotes’ role in this region’s food web and their place as a novel predator across the landscape.

  • The Ecology of Rehabilitated Sloths in Panamá*
  • Chelsea N. Morton; Clayton K. Nielsen; Andrew D. Carver; Nestor J. Correa; Yiscel S. Yanguez
    The field of wildlife rescue and rehabilitation continues to grow as human expansion increases the rate of deforestation in Latin America. Wild animals that are often rescued from becoming orphaned or injured are rehabilitated in captivity until considered suitable for release back into the wild. Sloths, (Bradypus spp. and Choloepus spp.) are a common species admitted to rescue centers throughout Latin America due to their poor dispersal abilities and vulnerability to anthropogenic impacts. Although post-release monitoring has been fundamental in measuring the success of wildlife rescue programs, few studies have assessed the long-term outcomes of releasing hand-reared sloths back into the wild. We are studying the post-release success of Hoffmann’s two-toed sloths (C. hoffmanni) in central Panamá during 2019-2020. Ten sloths rescued from the wild and raised in captivity have been radiomarked and placed in an outdoor 500-m2soft-release enclosure for 3 months, where behavioral observations are being conducted to quantify activity budgets. Sloths are then released in an adjacent national park and radiotracked for dispersal movements, habitat selection, and survival for a minimum of 12 months. Dispersal patterns are calculated from movement paths obtained via connecting GPS locations of individual sloths. Habitat preference is analyzed using a paired analysis approach where 7 microhabitat variables are measured at sloth radiolocations versus paired random locations. Understanding the adaptations of rehabilitated sloths will guide future assessments of the contributions made by individuals to sustain wild populations of a species with such low dispersal capacity and unknown population trends. Obtaining data from post-release monitoring will provide useful information to make improvements in current guidelines of sloth rehabilitation for rescue centers throughout Latin America.

  • The Experience of Chinese Ngos in Africa-China Animal Protection Collaboration:A Case Study of China House
  • Hongxiang Huang; Ruoqu Zhou; Yanran Lyn; Yimuxue ZHANG
    Along with the economic booms of the Belt and Road Initiative, China, as one of the largest African illegal wildlife markets, plays a controversial role on the global stage, especially in Africa. On this background, what is the relationship between animal protection and China-Africa relations? What role do Chinese NGOs play in Africa-China animal protection? How can Chinese NGOs influence IR in this way? This dissertation explores these questions by analyzing the case of China House. Founded in Kenya in 2014, China House has organized various social engagement activities related to animal protection in Africa, such as the China-Africa Wildlife Conservation Cooperation Conference in South Africa, which the Chinese Embassy has attended.
    This dissertation evaluates these activities’ effectiveness and influence on IR and makes a comparative study on non-Chinese NGOs in Africa. Adopted methods include literature research on unpublished internal reports and interviews with various stakeholders: China House’s staff and volunteers, Chinese communities and local communities in Africa.Based on the case study, this dissertation argues that: (1) As animal welfare and rights become a global issue, animal protection has become a critical factor in IR. China’s negative image of being involved in illegal wildlife trade does harm to China-Africa business and social cooperation. (2) Thanks to their deep understanding of the Chinese community in Africa, Chinese NGOs play a unique role in integrating the Chinese community into Africa’s animal protection activities. (3) The participation of Chinese NGOs in animal protection can change Africans’ perception of the Chinese and enhance the understanding between two sides, and therefore positively influence China-Africa relations.

  • Population Crash of An Endemic South African Cyprinid: The Role of Non-Native Fish, Drought and Other Environmental Factors
  • Cecilia Cerrilla; Jeremy Shelton; Bruce Paxton; Mandy Schumann; Cecile Reed
    South Africa’s Cape Fold Ecoregion (CFE) harbors exceptionally high freshwater fish endemism, yet the majority of these species are threatened with extinction. The Clanwilliam sandfish (Labeo seeberi), an endangered cyprinid, has declined across its range in the CFE and currently exists in only a handful of tributaries of the Doring River in severely fragmented populations. The last remaining recruiting sandfish population occurs in the Oorlogskloof River, making this tributary one of critical conservation value. I analyzed a six-year dataset comprising fish survey data from 38 sites along 25km of the Oorlogskloof River to characterise spatio-temporal variation in sandfish abundance and size structure and evaluate the relative influence of different environmental factors on sandfish population trends. The environmental factors considered included other fish in the system, especially three non-native fishes (banded tilapia Tilapia sparrmanii, smallmouth bass Micropterus dolomieu and bluegill sunfish Lepomis macrochirus), and various environmental factors. The results show that sandfish have experienced a 93% decline in the Oorlogskloof since 2013 and that the ongoing drought may be preventing recovery. They also suggest that banded tilapia do not adversely affect sandfish, while predation of juveniles by smallmouth bass and/or bluegill sunfish apparently reduces the abundance of sandfish, especially of juveniles, where these non-native fish are present. Management of the river’s sandfish population should focus on precautionary actions such as continued monitoring and clearing surrounding dams of smallmouth bass and bluegill sunfish in order to prevent accidental introduction of these species further upstream than where they are currently found.


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