Geology topics

Dewayne Fox

Publications and source records attributed to Dewayne Fox.

5 recordsLinked to original sources

USGS2025

Cryptic life history diversity supports endangered species recovery in an ultra-urbanized landscape

Urban landscapes are often overlooked in conservation planning, allowing human activities to take precedence in ecosystem management. However, even heavily modified environments can support diverse species profiles, but continued expansion of the human footprint could transform these biodiversity hotspots into ecological traps that serve as hidden catalysts for demographic declines. In the backdrop of one of the world’s most urbanized landscapes-New York City, USA—is a federally endangered population of shortnose sturgeon ( Acipenser brevirostrum ) that has been quietly recovering for several decades despite many demographic threats. Here, we identify a unique behavioral phenotype of shortnose sturgeon that occupies habitats in New York Harbor in late spring and fall, likely using the area to optimize bioenergetic processes. As this study highlights, urbanized environments can be a nexus for cryptic phenotypic diversity which, if overlooked, can disrupt eco-evolutionary processes and contribute to population and species loss.

New York↗

USGS2025

Sounds of Atlantic sturgeon spawning: First description and opportunities for riverine endangered species conservation with passive acoustic monitoring

Effective recovery plans for endangered species rely on insights into species’ ecology to identify risks and develop population recovery strategies. Data gaps pose challenges for many species of conservation concern, particularly those with cryptic behaviors or that occupy difficult-to-access habitats. Sounds produced by these species offer an effective means of observing many such marine and aquatic species, and for this reason, passive acoustic monitoring has emerged as an important study and assessment approach in marine systems. This approach is only just beginning to be applied for aquatic species monitoring in freshwater habitats. Atlantic sturgeon Acipenser oxyrinchus , a species of conservation concern along the US East Coast, remains poorly understood due to persistent data gaps despite years of conservation efforts. While sounds have been described for other sturgeons, sounds from Atlantic sturgeon have not yet been reported. Here, we characterized acoustic cues associated with Atlantic sturgeon in the Hudson River, New York, USA, and identified a low-frequency (44 Hz peak frequency) signal strongly correlated with the occurrence of telemetry-tagged adults which enter the river to spawn. We corroborated these efforts with recordings of captive Atlantic sturgeon, in which we detected the same sound type during a spawning period. Our findings provide an opportunity to develop passive acoustic monitoring strategies for Atlantic sturgeon, offering a non-invasive tool for understanding the spatiotemporal distribution of spawning activity across their range. We demonstrate potential applications of passive acoustic monitoring to inform sturgeon conservation and management, including characterizing habitat use, identifying cross-species interactions, and providing abundance indices.

New York↗

USGS2025

Combining acoustic telemetry and side-scan sonar to estimate abundance of endangered shortnose sturgeon in the Hudson River, New York

For endangered shortnose sturgeon (Acipenser brevirostrum), the ability to estimate and monitor population size is critical for tracking species’ recovery. Yet, contemporary abundance estimates have not been completed for many shortnose sturgeon populations, largely owing to the difficulty in using traditional abundance estimators for sturgeons. Here, we estimate the adult shortnose sturgeon population size of the Hudson River, NY by integrating data from two largely passive sampling methods – acoustic telemetry and side-scan sonar – into a Bayesian hierarchical model of abundance. We estimated the adult abundance to be 69,798 individuals (95% CI = 9,207-185,666), making the Hudson River the largest extant shortnose sturgeon population. Despite this, the population remains vulnerable to localized disturbances, as over 40% of the population congregated in a small overwintering habitat that coincides with an area of high anthropogenic activity. Accordingly, recurrent demographic surveys may be beneficial for gaining insight into the relative effects of anthropogenic and naturally stochastic processes shaping shortnose sturgeon demography. Our modeling framework provides a relatively low-cost alternative for future demographic monitoring of species of conservation concern.

New York↗

USGS2025

Reconstructing relative abundance indices for Atlantic sturgeon using hierarchical ecological models

Objective The Atlantic Sturgeon Acipenser oxyrinchus is a wide-ranging, long-lived diadromous fish that is endangered in most of its range. Our objective was to develop and apply long-term, detection-corrected indices of relative abundance for juvenile and adult Atlantic Sturgeon in the Hudson River, New York, United States, to support population monitoring and stock assessment. Methods We used long-term gill-net catches to estimate relative abundances of juvenile and adult Atlantic Sturgeon while accounting for imperfect detection within an N- mixture modeling framework. We validated the model framework using a simulation–estimation framework based on mean parameter estimates from the adult Atlantic Sturgeon relative abundance index. Results Simulation testing indicated that absolute abundance estimates may be biased low due to poor characterization of detection probabilities. However, model estimates of relative abundance tracked simulated abundance trends well. Juvenile relative abundance estimates followed similar trends as raw gill-net catches but were less variable among years when corrected for detection probability. Relative abundance of juveniles increased from 2004 to 2015 prior to declining through 2022, with little evidence for change between the start and end of the survey. Detection-corrected indices for adult sturgeon indicated a consistent increase in relative abundance that was not readily apparent in raw catch indices. Conclusions Detection-corrected catch indices can provide improved characterization of Atlantic Sturgeon relative abundance dynamics over raw gill-net catches through use of N- mixture models. The approach has broad applicability to data types that are commonly collected for understanding population trends in stock assessment. Estimation of absolute abundance and other population demographics germane to management would benefit from alternative or auxiliary data collected through approaches such as side-scan sonar or acoustic telemetry, which are increasingly common for monitoring sturgeon populations.

New York↗

USGS2024

Spawning run estimates and phenology for an extremely small population of Atlantic Sturgeon in the Marshyhope Creek–Nanticoke River system, Chesapeake Bay

Objective Once thought to be extirpated from the Chesapeake Bay, fall spawning runs of Atlantic Sturgeon Acipenser oxyrinchus have been rediscovered in the Marshyhope Creek (MC)–Nanticoke River (NR) system of Maryland, United States. High recapture rates in past telemetry surveys suggested a small population in the two connected tributaries. This study aims to generate estimates of abundance and understand within system connectivity for spawning runs in 2020 and 2021. Methods Data from mobile side-scan sonar surveys and detections of acoustically tagged adults on stationary telemetry receivers were analyzed in an integrated model to estimate spawning season abundance and examine run timing and system connectivity for this population. An array of acoustic receivers was deployed throughout the MC–NR system to monitor the movement of tagged fish during the spawning run period from mid-August to late October. Side-scan sonar surveys were conducted weekly in September in an area of high spawner aggregation to generate count data on spawning run abundance. Result In 2020 and 2021, 32 (95% credible interval [CRI] = 23–47) and 70 (95% CRI = 49–105) Atlantic Sturgeon, respectively, used the MC–NR system. The lower estimate for 2020 coincided with an earlier end to the spawning run related to cooler September temperatures in that year. Conclusion In both years, high spawning run connectivity between MC and the upper NR was observed. Overall, run estimates supported previous hypotheses that the MC–NR system supports a very small population and that both MC and the upper NR serve as important areas for spawning activity.

Chesapeake Bay, Marshyhope Creek–Nanticoke River s↗