Scholarly Works, Fish and Wildlife Conservation

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Research articles, presentations, and other scholarship

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A Unionid Mussel Biodiversity Hotspot Experiencing Unexplained Declines: Evaluating the Influence of Chemical Stressors Using Caged Juveniles
Wilson, W. Aaron; Bergeron, Christine; Archambault, Jennifer; Unrine, Jason; Jones, Jess; Beaty, Braven; Shea, Damian; Lazaro, Peter R.; Callihan, Jody L.; Rogers, Jennifer J.; Cope, W. Gregory (MDPI, 2025-07-22)
Unionid mussel populations in a section of the Clinch River in Virginia, USA, has declined substantially, but the causes of the decline remain unknown. To investigate this zone of decline (ZOD), we deployed juvenile freshwater mussels (Villosa iris in 2012 and Lampsilis fasciola in 2013) in both cages and silos at sites within the Clinch River System. We analyzed mussel tissues for trace element and organic contaminant concentrations, shells for trace elements, and environmental media (total water, dissolved water, particulate sediment, and bedload sediment) for both inorganic and organic contaminants. We found a few differences between mussels deployed in cages and those deployed in silos: survival was slightly lower in cages due to periodic sedimentation. Our results identified the ZOD based on the accumulation of trace elements (notably As, Cu, Fe, Mn, Ni, and Sr), polycyclic aromatic hydrocarbons (PAHs), and δ¹⁵N enrichment, with especially high concentrations found in the human-impacted tributaries, Dumps Creek and Guest River. Some correlations were found between environmental media and both mussel tissues and shells. In particular, PAHs and Mn had several significant relationships between bioaccumulated concentrations and environmental concentrations. Finally, Co, Cu, Fe, and V in soft tissues negatively correlated with mussel growth, whereas bioaccumulated PAH concentrations correlated negatively with resident mussel densities.
The Bat Signal: An Ultraviolet Light Lure to Increase Acoustic Detection of Bats
Freeze, Samuel R.; Deeley, Sabrina M.; Litterer, Amber S.; Freeze, J. Mark; Ford, W. Mark (MDPI, 2025-08-21)
Bats are a taxa of high conservation concern and are facing numerous threats including widespread mortality due to White-Nose Syndrome (WNS) in North America. With this decline comes increasing difficulty in monitoring imperiled bat species due to lower detection probabilities of both mist-netting and acoustic surveys. Lure technology shows promise to increase detection while decreasing sampling effort; however, to date research has primarily focused on increasing physical captures during mist-net surveys using sound lures. Because much bat monitoring is now performed using acoustic detection, there is a similar need to increase detection probabilities during acoustic surveys. Ultraviolet (UV) lights anecdotally have been shown to attract insects and thereby attract foraging bats for observational studies and to experimentally provide a food source for WNS-impacted bats before and after hibernation. Therefore, we constructed a field-portable and programmable UV lure device to determine the value of lures for increasing acoustic detection of bats. We tested if the lure device increased both the echolocation passes and feeding activity (feeding buzzes) across a transect of bat detectors. There was an increase in feeding activity around the UV light, with a nuanced, species-specific and positionally dependent effect on echolocation passes received. The UV light lure increased echolocation passes for the eastern red bat (Lasiurus borealis), little brown bat (Myotis lucifugus), and evening bat (Nycticeius humeralis), but decreased passes of the North American hoary bat (Lasiurus cinereus). The northern long-eared bat (Myotis septentrionalis) showed a negative response within the illuminated area but increased echolocation activity outside the illuminated area during lure treatment and activity was elevated at all positions after the lure was deactivated. Our study demonstrates some potential utility of UV lures in increasing the feeding activity and acoustic detection of bats. Additional research and development of UV lure technology may be beneficial, including alternating on and off periods to improve detection of light-averse species, and improving echolocation call quality along with the increase in received passes.
Home range size and resource use of male eastern wild turkeys in West Virginia
De La Cruz, Jesse L.; Rauch, Steven E.; Anderson, James T. (2025)
Age-related differences in habitat use are commonly observed among eastern wild turkeys (Meleagris gallopavo silvestris). We investigated home range size and within home range habitat (third-order) selection of 55 radio-tracked adult and juvenile male wild turkeys across five ecological regions of West Virginia from September 2004 to August 2007. Mean core (50% fixed-kernel density estimates [KDE]; adult = 363.2 ha; juvenile = 447.6 ha) and peripheral (95% KDE; adult = 1635.4 ha; juvenile = 2105.8 ha) home range size estimates were large, but comparable to both historical and contemporary published estimates, particularly from forest-dominated areas. Resource use differed between age classes, particularly in relation to forest fragmentation metrics. Both adults and juveniles preferentially selected for deciduous forests, while avoiding developed land and open water. However, adults selected for forest edges and avoided non-forest areas and non-core forest patches. In contrast, juveniles utilized most fragmentation classes in proportion to their availability but avoided large core (>200 ha) forest areas. To benefit eastern wild turkey populations in West Virginia, management efforts should prioritize the creation and maintenance of forest edges in deciduous stands <200 ha, particularly in regions with minimal anthropogenic influence.
Assessing tricolored bat acoustic monitoring for regulatory purposes in relation to reproductive period, cover type, and presence of eastern red bats
Ford, W. Mark; Thorne, Emily D.; De La Cruz, Jesse L.; Silvis, Alexander; Kuczynska, Vona; Armstrong, Michael P.; King, R. Andrew (2025)
The U.S. Fish and Wildlife Service (USFWS) allows use of acoustical surveys and automated identification software to determine the presence of the proposed endangered tricolored bat (Perimyotis subflavus). Analytical software is required to assess the probability of species absence on a sitenight basis using a maximum likelihood estimator (MLE) that accounts for interspecific misclassification rates. The current standard for occupancy determination is a returned MLE P-value ≤0.05 at the nightly level irrespective of the number of files identified as tricolored bats. For this species, MLE P-values can vary based on presence and proportion of other bat species with similar echolocation characteristics such as the eastern red bats (Lasiurus borealis). Large numbers of eastern red bat echolocation passes may lead to a swamping effect, causing false-negative tricolored bat determinations. Therefore, we investigated the relationship between MLE values returned by Kaleidoscope Pro automated software and nightly tricolored bat counts, along with count proportion relative to eastern red bat detections, for various summer reproductive stages (e.g., pregnancy, lactation, and volancy) and vegetation cover types. We also examined the effectiveness of using the 14-site-night level of effort (LOE) set by USFWS for the endangered northern long-eared bat (Myotis septentrionalis) for determining how many cumulative nights of tricolored bat presence would occur under that LOE standard. Automated identification software identified tricolored bat echolocation pass presence at the file level. However, software returned nightly MLE values that were not significant when tricolored bat passes were infrequent (<20 passes) and proportionally low relative to eastern red bat passes, suggesting an acoustic swamping effect. The probability of a significant MLE for tricolored bats was greatest during the late summer when juvenile bats were volant and actively foraging on the landscape. Cumulative nights of tricolored bat presence based on significant MLE values were greatest during the late summer and in riparian cover types.
From Data Deficient to Big Data in Shark Conservation
Ferretti, Francesco; Jenrette, J.; Moro, S.; Butner, C.; Fox, Edward A.; Haddock, S.H.D.; Jorgensen, S.J.; Hastie, T. (Wiley, 2025-08-01)
Citizen science is increasingly harnessed worldwide to gather data otherwise requiring a prohibitive investment of funding and time. Meanwhile, the revolution in digital communication offers opportunities from crowdsourcing, big data approaches and social network mining to quickly and cost-effectively fill major gaps in knowledge necessary to protect endangered populations. Sharks are among the most endangered and data-poor vertebrates in the ocean. Mainly due to overfishing, many shark populations are declining worldwide, while most species lack basic abundance, distribution and life-history data. Hence, filling knowledge gaps across taxa, ecosystems, and regions is urgently needed to increase our understanding of their ecology, develop effective conservation actions and reverse their loss. Here, we introduce a novel citizen science and crowdsourcing approach for conservation through sharkPulse, a new platform automating data ingestion and organisation to build the largest database of shark occurrence records to date. Designed to complement and extend similar biodiversity monitoring tools relying heavily on user submissions, sharkPulse aims to source large streams of online shark images and transform them into occurrence records, filling knowledge gaps in shark ecology and biology. This platform offers a blueprint to leverage AI and big data approaches, social network data mining and participatory science to efficiently and continuously source visual media materials and transform the monitoring of data-limited marine and terrestrial animal populations.
Who welcomes the bear: Evidence for a disconnect between attitudes and acceptability of killing brown bears
Rastgoo, Reyhane; Nayeri, Danial; Mohammadi, Alireza; Bath, Alistair J.; Farhadinia, Mohammad S. (Wiley, 2025-07-23)
1. Acceptability of large carnivores is influenced by socio‐psychological factors and is crucial to coexistence. When large carnivores cause real or perceived threats such as damage to local economy or safety, people may engage in lethal control. However, in the presence of legal protection for the species and associated penalties, lethal retaliation can diminish or happen elusively. Therefore, it is helpful for managers to understand people's attitudes and acceptability associated with support for killing large carnivores in conflict situations and the demographics of those involved in lethal retaliation. 2. We interviewed 390 respondents living in 26 villages in northern Iran, where communities are largely dependent on agriculture and livestock for their livelihood and conflicts with brown bears (Ursus arctos) are common. Our goal was to assess the acceptability of killing bears in four different scenarios, from low‐intensity to high‐intensity interaction. 3. The results showed that although respondents generally had a slightly positive attitude towards bears, those with negative attitudes were associated with higher acceptability of killing bears. The mean acceptability of killing bears increased as human–bear interaction intensified. Younger, less educated and female respondents were more supportive of killing bears, while respondents with an alternative source of income were less accepting of killing them. 4. We provide five recommendations to foster coexistence, including leveraging positive attitudes through strategies like building advocacy networks, promoting inclusive outreach programmes, particularly for female and younger respondents. Also, we recommend emergency conflict mitigation teams take immediate action for conflict mitigation in areas with higher acceptance of killing bears to prevent retaliatory behaviour. Furthermore, providing an alternative source of income and focusing on preventive methods and effective strategies are recommended.
A Practitioner’s Guide to Landowner Participation in the Longleaf Pine Restoration and the Conservation Reserve Program
Rastgoo, Reyhane; Oppong, Kingsley; Allred, Shorna; Holland, Katie; Dayer, Ashley A. (2025-07)
At the beginning of the 17th century, the southeastern United States was home to an estimated 90 million acres of longleaf pine forests, which supported nearly 900 plant species. However, due to extensive logging, land conversion, and fire suppression, these forests were drastically reduced. Efforts to restore this critical ecosystem on private lands have been significantly supported by cost-share programs, including the Conservation Reserve Program (CRP). CRP was first authorized in the 1985 Farm Bill and designed to encourage private landowners and agricultural producers to convert marginal cropland to conservation covers, including longleaf pine. Approximately 400,000 acres of longleaf pine have been restored through the program. In addition, the USDA Natural Resources Conservation Service (NRCS) Longleaf Pine Initiative (LLPI), launched in 2010, has supported producers in restoring over 870,000 acres of longleaf pine on private lands. Combined with other conservation efforts, these initiatives have increased the total area of longleaf pine forests from approximately 3.4 million acres to 5.2 million acres over the past 40 years. This literature review was conducted by members of the Dayer Human Dimensions Lab in the Department of Fish and Wildlife Conservation at Virginia Tech, in collaboration with Professor Shorna Allred and Kingsley Oppong (research assistant) from the Department of Geography and Environment at the University of North Carolina at Chapel Hill. This literature review is part of a larger study examining motivations and challenges to participation in the Conservation Reserve Program and was funded by the USDA (grant #FSA23CPT0013578). The purpose of this document is to support practitioners who aim to promote landowner participation in longleaf pine restoration conservation programs. It provides an overview of the longleaf pine ecosystem and the role of conservation programs in its restoration, with particular focus on CRP’s contributions to longleaf pine restoration. The review also explores landowners’ motivations and obstacles to participation in conservation programs and examines post-CRP land use options, including the persistence of longleaf pine forests through CRP.
Supporting Participation of Disabled Wildlife Viewers: Recommendations from focus groups
Sinkular, Emily N.; McGregor, Freya A.; Dayer, Ashley A. (2025-05)
Wildlife viewing, defined as “intentionally observing, feeding, or photographing wildlife; or traveling to parks or natural areas to observe, feed, or photograph wildlife” (U.S. DOI & U.S. FWS, 2023) is one of the most popular wildlife-associated recreation activities in the United States, with more than half of all Americans participating in 2022 (U.S. DOI & U.S. FWS, 2023). One in four Americans has a disability – a proportion anticipated to rise with the aging population (Centers for Disease Control and Prevention, 2018). Globally, 15% of the population is neurodivergent. In 2021, with the support of a Multistate Conservation Grant, Virginia Tech found that 39% of wildlife viewers reported experiencing accessibility challenges, defined as “the difficulties someone experiences in interacting with or while using the physical or social environment while trying to engage in a meaningful activity (such as wildlife viewing). This may be a result of a mobility challenge, blindness or low vision, intellectual or developmental disabilities (including Autism), mental illness, being Deaf or hard of hearing, or other health concerns” (Sinkular et al., 2024.). Despite the large number of Americans and wildlife viewers with accessibility challenges, many likely due to disabilities, little is known about best practices to support their participation in wildlife viewing. Additionally, state wildlife agencies are required by the Americans with Disabilities Act to ensure people with disabilities have equal opportunities to participate in the programs they offer U.S. Department of Justice (1990). Many state fish and wildlife agencies do not have the capacity to explore best practices for Universal Design (principles used when designing environments, products or communications to be usable by all and as user-friendly as possible; Aslaksen et al., 1997), the resources to conduct focus groups to hear from disabled constituents about their needs and experiences, or the training or expertise around disability or accessibility. This project is a collaboration between the Dayer Human Dimensions Lab at Virginia Tech and the Association of Fish and Wildlife Agencies’ Wildlife Viewing and Nature Tourism Group, designed to answer these questions relevant to state agencies and their partners: 1. What motivates people who are disabled and neurodivergent to participate in wildlife viewing? 2. Which people and groups support disabled and neurodivergent wildlife viewers? 3. What features do wildlife viewing programs have that make them inclusive to disabled and neurodivergent participants? 4. What makes wildlife viewing locations accessible to disabled and neurodivergent participants? 5. How can staff and volunteers at wildlife viewing locations, and state wildlife agencies, practice individual and organization allyship to disabled and neurodivergent wildlife viewers? Our hope is that this report will enable wildlife viewing staff and volunteers nationwide to more effectively serve all members of the wildlife viewing community interested in viewing and engaging with state wildlife agencies.
The Quantification of Morphological Variation and Development of Morphology-Based Keys to Identify Species of Fusconaia and Pleurobema (Unionidae) in the Green River, Kentucky, USA
Olivera-Hyde, Miluska; Jones, Jess W.; Hallerman, Eric M. (MDPI, 2025-04-21)
We quantified morphological variation among genetically identified specimens of Fusconaia flava, F. subrotunda, Pleurobema cordatum, P. plenum, P. sintoxia, and P. rubrum inhabiting the Green River, Kentucky, species with shells that are morphologically similar to each other and thus difficult to identify. Molecular identifications then were compared with phenotype-based identifications by experts, who on average correctly identified 70% of the specimens. Expert identification of the putative species P. rubrum and P. sintoxia resulted in them usually being identified as the latter. Multi-variable decision tree analysis was conducted to determine the best suite of morphological variables for identifying live mussels and shells to species. Cross-validation error rates for these analyses were 12.6% and 4.14% for live mussels and shells, respectively. Both random forest and decision tree analyses showed the most important variables to be the presence/absence of a sulcus and shell shape (trapezoidal, circular, oval, equilateral triangle, or isosceles triangle). Dichotomous keys for identifying shells and live mussels were developed based on key morphological characteristics readily identifiable in the field, including foot color, beak direction, and beak position relative to the anterior margin. However, a definitive identification of these species may still need to rely on molecular methods, especially for endangered species.
Prescribed fire promotes colonization by the Florida bog frog
Brooks, George C.; Gorman, Thomas A.; Proctor, Christine M.; Rincon, Brandon K.; Haas, Carola A. (2025-04-09)
Background: Understanding the link between prescribed fire and occupancy dynamics can aid in managing at-risk species. Knowledge of how fire return interval influences rates of colonization and persistence is essential to effectively mitigate extinction risk, particularly for species endemic to fire-maintained habitats with restricted geographic ranges. The current geographic range of the Florida bog frog (Rana okaloosae, hereafter bog frog) is largely restricted to one military installation in the Florida panhandle. The bog frog is currently listed as a state species of special concern owing to its inherent rarity and habitat loss across its limited range. We conducted call surveys for bog frogs at 151 stream-associated sites on Eglin Air Force Base from 2006 to 2022 to map their distribution and evaluate the effectiveness of habitat management. We constructed a spatially explicit, dynamic occupancy model to identify habitat characteristics associated with bog frog presence and quantify the effect of prescribed fire on turnover dynamics. Results: Historical fire return interval was the only predictor of initial site occupancy; sites that burnt every 2 years on average from 1985 to 2005 were twice as likely to be occupied in 2006 as sites that burnt once every 10 years in that time period. Additionally, we found that colonization rates were a function of proximity to neighboring sites and burn frequency. Most dispersal events occurred between sites less than 0.33 km apart and unoccupied sites more than 2 km from their nearest neighbors were never colonized. Colonization rates were higher at sites that had seen an increase in burn frequency during the study period compared to the preceding two decades. Conclusions: The bog frog benefits from frequent fire in its native stream habitat. Conservation activities should focus on protecting high-quality sites and targeted burns to restore fire-suppressed sites near occupied sites. More broadly, our study highlights the value of long-term monitoring to ensure management activities for at-risk species match the scale of dynamic biological processes.
Hantavirus in rodents in the United States: Temporal and spatial trends and report of new hosts
Astorga, Francisca; Alkishe, Abdelghafar; Paansri, Paanwaris; Mantilla, Gabriel; Escobar, Luis E. (Wiley, 2025-03-16)
In North America, the rodent-borne hantavirus pulmonary syndrome ispredominantly caused by the Sin Nombre virus, typically associated with the deer mouse Peromyscus maniculatus. Utilizing data from the National Ecological Observatory Network (NEON) hantavirus program, we assessed factors that may influence the spatial and temporal distribution of hantavirus inrodent populations across the United States. Between 2014 and 2019, the NEON hantavirus program conducted 104,379 small mammal captures and collected 14,004 blood samples from 49 species at 45 field sites. Our study identified 296 seropositive samples across 15 rodent species, including 8 Peromyscusspecies. We describe six new species with hantavirus seropositive samples not previously reported as hantavirus hosts. The highest number of seropositivesamples was obtained from Pe. maniculatus (n = 116; 2.9% seroprevalence),followed by Peromyscus leucopus (n = 96; 2.8%) and Microtus pennsylvanicus(n = 33; 4.2%). Hantavirus seroprevalence showed an uneven spatial distribution, with the highest seroprevalence found in Virginia (7.8%, 99 seropositivesamples), Colorado (5.7%, n = 37), and Texas (4.8%, n = 19). Hantavirus sero-positive samples were obtained from 32 sites, 10 of which presented seropositive samples in species other than Pe. maniculatus or Pe. leucopus. Seroprevalence was inconsistent across years but showed intra-annual bimodal trends, and in Pe. maniculatus and Pe. leucopus, the number of captures correlated with sero-prevalence in the following months. Seroprevalence was higher in adult males, with only one seropositive sample obtained from a juvenile Peromyscus truei. Higher body mass, presence of scrotal testes, and nonpregnant status were associated with higher seropositivity. The NEON dataset, derived from a multiyear and structured surveillance system, revealed the extensive distribution of hantavirus across broad taxonomic and environmental ranges. Future research should consider winter season surveillance and continued analyses of stored samples for a comprehensive spatiotemporal study of hantavirus circulation in wildlife. Global changes are expected to affect the dynamics of rodent populations by affecting their availability of resources and demography and, consequently, may modify transmission rates of rodent-borne zoonotic pathogens such as hantavi-rus. This study can be considered a baseline to assess hantavirus patterns across host taxa, geographies, and seasons in the United States.
Spatial epidemiology of Tabanus (Diptera: Tabanidae) vectors of Trypanosoma
Marques, Roberta; Jiménez-García, Daniel; Escobar, Luis E.; Krolow, Tiago K.; Krüger, Rodrigo F. (2025-04-03)
Background: Trypanosoma are protozoa parasites that infect animals and can cause economic losses in cattle production. Trypanosoma live in the blood and are transmitted by hematophagous insects, such as flies in the genus Tabanus. Using ecological niche models, we explored the current geography of six common Tabanus species in Brazil, which are considered vectors of Trypanosoma vivax and Tr. evansi in the Neotropics. Methods: We used georeferenced data and biotic and abiotic variables integrated using a fundamental ecological niche modeling approach. Modeling results from six Tabanus species were used to identify risk areas of Trypanosoma transmission in Latin America accounting for area predicted, landscape conditions, and density of livestock. We performed Jaccard, Schoener, and Hellinger metrics to indicate the ecological niche similarities of pairs of Tabanus species to identify known and likely vectors overlapping in distribution across geographies. Results: Our results revealed significant ecological niche similarities for two Tabanus species (T. pungens and T. sorbillans), whereas T. triangulum and T. importunus have low ecological similarity. Ecological niche models predicted risk of Trypanosoma transmission across Neotropical countries, with the highest risk in southern South America, Venezuela, and central Mexico. Conclusions: More than 1.6 billion cattle and 38 million horses are under a threat category for infection risk. Furthermore, we identified specific areas and livestock populations at high risk of trypanosomiasis in Latin America. This study reveals the areas, landscapes, and populations at risk of Trypanosoma infections in livestock in the Americas.
Assessment of 18 Years of Genetic Marker-Assisted Selection and Augmentation of Native Walleye in the Upper New River, Virginia, USA
Harris, Sheila; Palmer, George; Copeland, John R.; Williams, Joe; Hallerman, Eric M. (MDPI, 2025-03-06)
Walleye Sander vitreus is a valued sportfish in eastern North America, including the upper New River of Virginia, where individuals can grow to a large size (>7 kg). After construction of dams, especially Claytor Dam in 1939, the population declined and non-native walleye were stocked. Stocking of non-native walleye was stopped in 1997, and molecular marker data showed that the presumptive native population had persisted. To restore the native stock, selection of broodstock candidates bearing native marker alleles and hatchery-based augmentation have been practiced over a 20-year period. We evaluated the success of the marker-assisted selection and hatchery-based augmentation program. Marker-assisted selection of native New River walleye began with mean frequencies of marker alleles at microsatellite loci Svi17 and Svi33 of ~30%, and continuing selection has driven marker allele frequencies to ~65–70%. Numbers of walleye collected in fall gillnet and spring electrofishing surveys were responsive to augmentations with hatchery fish 2–3 years earlier. Stocking was not practiced in 2012–2013, and a decrease in walleye catch rates was noted in 2016, suggesting that the native New River walleye population still depends upon hatchery-based augmentation. We recommend the development of a small panel of single nucleotide polymorphism markers for more rigorous selection of broodstock representative of the native walleye population.
Environmental stress reduces shark residency to coral reefs
Williamson, Michael J.; Tebbs, Emma J.; Curnick, David J.; Ferretti, Francesco; Carlisle, Aaron B.; Chapple, Taylor K.; Schallert, Robert J.; Tickler, David M.; Block, Barbara A.; Jacoby, David M. P. (Nature Portfolio, 2024-09-09)
Coral reef ecosystems are highly threatened and can be extremely sensitive to the effects of climate change. Multiple shark species rely on coral reefs as important habitat and, as such, play a number of significant ecological roles in these ecosystems. How environmental stress impacts routine, site-attached reef shark behavior, remains relatively unexplored. Here, we combine 8 years of acoustic tracking data (2013-2020) from grey reef sharks resident to the remote coral reefs of the Chagos Archipelago in the Central Indian Ocean, with a satellite-based index of coral reef environmental stress exposure. We show that on average across the region, increased stress on the reefs significantly reduces grey reef shark residency, promoting more diffuse space use and increasing time away from shallow forereefs. Importantly, this impact has a lagged effect for up to 16 months. This may have important physiological and conservation consequences for reef sharks, as well as broader implications for reef ecosystem functioning. As climate change is predicted to increase environmental stress on coral reef ecosystems, understanding how site-attached predators respond to stress will be crucial for forecasting the functional significance of altering predator behavior and the potential impacts on conservation for both reef sharks and coral reefs themselves.
Ecological interactions between 19 shark species in the Indian Ocean
Gee, Emma; Romanov, Evgeny V.; Curnick, David; Block, Barbara; Ferretti, Francesco (IOTC, 2024-09-07)
Apex predators such as sharks are a critical component of ocean ecosystems. Yet the ecosystem consequences of shark declines remain poorly understood, primarily because of a lack of population and community baselines. The Indian Ocean is especially data-poor in ecological data, and even moreso in historical data. We utilized a longline survey dataset from 1966 through 1989 that spanned the majority of the Indian Ocean and recorded 19 shark species. This time period corresponds to the start of large-scale industrial fishing in the region. Trends across the species were highly variable; life history and fishing pressure metrics were not able to explain differences in responses between species, suggesting that changes in ecological interactions such as competition and predation had a prevalent role historically. To further explore ecological interactions between the species, we conducted a literature review of the study species’ diets with a focus on intra-guild predation. We constructed an interaction web to identify keystone species. Several species were neither predator nor prey of other sharks, suggesting that competition may be the more salient relationship to other sharks. Overall, species with broader habitat preferences and smaller individuals are now a larger part of the pelagic shark community, whereas open-ocean species have declined. These results suggest that industrial fishing restructured shark communities and diminished the top-down control of sharks in pelagic ecosystems.
SharkTrack: an accurate, generalisable software for streamlining shark and ray underwater video analysis
Varini, Filippo; Gayford, Joel H.; Jenrette, Jeremy; Witt, Matthew J.; Garzon, Francesco; Ferretti, Francesco; Wilday, Sophie; Bond, Mark E.; Heithaus, Michael; Robinson, Danielle; Carter, Devon; Gumbs, Najee; Webster, Vincent; Glocker, Ben (2024-11-30)
Elasmobranchs (shark sand rays) are critical components of coral reef ecosystems and are often considered indicators of reef health (Roff et al., 2016). Yet, they are experiencing global population declines and effective monitoring of these populations is essential to their protection. Underwater stationary videos, such as those from Baited Remote Underwater Video Stations (BRUVS), are critical for understanding elasmobranch spatial ecology and abundance. However, processing these videos requires time-consuming manual analysis. To address these challenges, we developed SharkTrack, a semi-automatic underwater video analysis software.SharkTrack uses Convolutional Neural Networks and Multi-Object Tracking to automatically detect and track elasmobranchs and provides an annotation pipeline to manually classify elasmobranch species and compute MaxN, the standard metric of relative abundance. We tested SharkTrack on BRUVS footage collected from threecoral reef locations unseen by the model during training, to demonstrate the model’sadaptability and effectiveness in different reef environments. SharkTrack computedMaxN with 89% accuracy over 207 hours of footage. The semi-automatic SharkTrackpipeline required two minutes of manual classification per hour of video, a 95%reduction of manual analysis time compared to traditional methods, estimated conservatively at 42 minutes per hour of video. These results suggest thatSharkTrack can be utilised to monitor elasmobranch populations across diverse coral reef ecosystems. Furthermore, the software’s flexible pipeline could serve as a blueprint for the development of species classifiers beyond elasmobranchs, enabling more comprehensive monitoring of coral reef biodiversity. We provide public access to SharkTrack, aiming to support future research in coral reef and marine conservation.
Position Statement on Shark Control Programs and Shark Culls
IUCN SSC Shark Specialist Group; Ferretti, Francesco (IUCN SSG. Shark Specialist Group, 2024-01-15)
The IUCN Species Survival Commission (SSC) is aware that lethal approaches to reducing the risk of human-shark interactions are increasingly being adopted around the world. Several governments either have active shark control programs (i.e., bather protection programs) or frequently implement shark culls in response to actual or perceived risk to humans. Hereby, the SSC outlines its position in relation to existing shark control programs and culls and provides context to allow managers and governments to make informed decisions when faced with delicate situations. We strongly encourage non-lethal approaches as a response and management option.
Morphological and Genetic Assessments of Coyote Diet in Qualla Boundary, North Carolina, Show Interaction with Humans
Miller, Caitlin M.; Linzey, Donald; Hallerman, Eric M. (MDPI, 2025-03-05)
Throughout the 20th century, coyotes (Canis latrans) expanded from their historical geographic range west of the Mississippi River to a current range of almost all of North America. Over the course of this expansion, coyotes have demonstrated diverse and variable omnivorous diets that change with the food resources available. This study examined the stomach contents of 25 coyotes in an area where they are relatively new, the Qualla Boundary in North Carolina, to better understand the diets of coyotes in this area. A combination of morphological identification and DNA barcoding was used to characterize the stomach contents of coyotes. Both plant and animal material were identified from anthropogenic and natural sources, the latter including native mammals. This study provides one example of the breadth and flexibility of coyote diets and helps build an understanding of how coyotes can adapt to new conditions.
How expectations of reciprocity impact donation and volunteer behavior to Nongame Wildlife Programs: a case study in Minnesota
Jennings, Kelsey K.; Dayer, Ashley A.; Chaves, Willandia A.; Osmundson, Cynthia L. (Taylor & Francis, 2025-01-11)
Our research examines motivations behind support for wildlife conservation efforts, primarily through volunteering and donations. Using the Minnesota Nongame Wildlife Program as a case study, we focus on nature-based support motivations. Using novel applications of two theoretical frameworks, we surveyed 763 respondents and found significant links between motivations and volunteer and donor behaviors. Biodiversity and ecological reciprocity were key drivers of donor behavior, while perks and natural place-based motivations strongly influenced volunteering. These findings suggest broad interests in wildlife conservation beyond organized events, extending to local communities and private lands. Our results underscore the importance of aligning volunteer experiences with preferred motivations to sustain engagement. Integrating community science programs, which activate volunteer motivations, could enhance engagement and support for wildlife conservation efforts. By focusing on supporters’ conservation impact and broadening engagement strategies for donors and volunteers, conservation organizations can adapt to changing landscapes and foster long-term support for wildlife conservation.
Demographic feedbacks during evolutionary rescue can slow or speed adaptive evolution
Draghi, Jeremy A.; McGlothlin, Joel W.; Kindsvater, Holly K. (The Royal Society, 2024-02-14)
Populations declining toward extinction can persist via genetic adaptation in a process called evolutionary rescue. Predicting evolutionary rescue has applications ranging from conservation biology to medicine, but requires understanding and integrating the multiple effects of a stressful environmental change on population processes. Here we derive a simple expression for how generation time, a key determinant of the rate of evolution, varies with population size during evolutionary rescue. Change in generation time is quantitatively predicted by comparing how intraspecific competition and the source of maladaptation each affect the rates of births and deaths in the population. Depending on the difference between two parameters quantifying these effects, the model predicts that populations may experience substantial changes in their rate of adaptation in both positive and negative directions, or adapt consistently despite severe stress. These predictions were then tested by comparison to the results of individual-based simulations of evolutionary rescue, which validated that the tolerable rate of environmental change varied considerably as described by analytical results. We discuss how these results inform efforts to understand wildlife disease and adaptation to climate change, evolution in managed populations and treatment resistance in pathogens.

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