Geology topics

Benjamin J. Schall

Publications and source records attributed to Benjamin J. Schall.

4 recordsLinked to original sources

USGS2026

Using eye lens stable isotopes to identify the rearing origin of fall age-0 walleye ( Sander vitreus )

Isotope values in fish eye lenses may be useful in differentiating rearing origins. We compared eye lens isotopic values of fall fingerling age-0 walleye ( Sander vitreus ) reared in a hatchery pond, a recirculating aquaculture system (RAS), and a natural lake. Using 10 fish per rearing source, we delaminated layers from one eye lens per fish to assess temporal changes in carbon (δ 13 C) and nitrogen (δ 15 N) and pulverized the whole second eye lens for δ 13 C, δ 15 N, and sulfur (δ 34 S). RAS-reared walleye values exhibited high precision among individuals and were δ 34 S enriched. Pond-reared walleye had lower δ 13 C and δ 15 N core values compared to other rearing sources. For δ 13 C and δ 15 N, values remained consistent among layers for RAS-reared walleye, δ 15 N slightly increased for pond-reared and lake-reared walleye, and δ 13 C increased substantially among subsequent layers in pond-reared walleye. Bayesian 95% ellipses did not overlap among rearing sources. These results demonstrate that eye lens stable isotope analysis may be a useful tool for differentiating hatchery-reared and wild large fingerling walleye, specifically from RAS- and pond-reared sources.

South Dakota↗

USGS2025

Predicting aquatic habitat connectivity across watershed boundaries: Implications for interbasin spread of nonindigenous aquatic species.

Understanding habitat connectivity is critical for managing nonindigenous aquatic species (NAS) spread. Dams and watershed boundaries can be impassable to NAS during typical conditions but may become temporarily passable during flooding. The goal of our project was to develop an approach for identifying locations of aquatic connectivity at a fine spatial scale along watershed boundaries using readily available data. To develop this approach, we focused on the potential for range expansion of invasive fish in the United States via possible cross-boundary habitat connections. First, we developed an index using metrics of elevation, watershed size, and geology at regular points along a watershed boundary to stratify points by likelihood of connectivity during high precipitation (>20 mm of precipitation in a 3-day period). We then used a subset of points across a gradient of connectivity likelihoods to gather Landsat-derived observed surface water data and developed a statistical model to predict surface water presence from landscape characteristics. We applied the model throughout the entire watershed boundary to identify locations of hydrologic connectivity during high-water events. The presence of surface water on watershed boundaries was predicted by the interactions between watershed boundary point elevation relative to the minimum adjacent HUC-12 elevations and watershed boundary point elevation relative to neighboring point elevations (marginal R 2 = 0.94). Our approach can be used to identify potential areas of surface water connectivity between watersheds quickly and easily at a fine spatial scale using readily available, remotely sensed data that can inform conservation and management actions across disciplines.

North Dakota, South Dakota↗

USGS2025

Reproductive characteristics and spawning potential ratio modeling of a vulnerable riverine specialist in the lower unchannelized Missouri River, USA

Reproductive characteristics for populations of imperiled, non-game species are not regularly studied but may be important for identifying factors associated with their population sustainability. Understanding reproductive traits of vulnerable species, particularly long-lived species, may provide insight for implementing management actions to respond to potential overharvest. This study aimed to assess the reproductive characteristics of a stable population of long-lived blue suckers ( Cycleptus elongatus ) in the unchannelized Missouri River in South Dakota. We obtained demographic information and gonads from 182 blue suckers collected in trammel nets in March 2021 and 2022. We used Bayesian generalized linear mixed-effects models to assess length and weight relationships with gonadosomatic index (GSI) and fecundity and used spawning potential ratios to model the influence of four minimum length limit scenarios. Total lengths of sampled fish ranged from 560 to 821 mm. Female GSI increased with length to ∼730 mm before declining, and male GSI remained consistent across lengths. Fecundity increased linearly with weight and with length to around 750 mm, after which the rate of increase slowed. Using a recent natural mortality estimate for this population, the spawning potential ratio under current no-limit regulations decreased rapidly as fishing mortality approached 0.10 but implementing a minimum length limit (e.g. 610- or 660 mm) could prevent the spawning potential ratio from falling below acceptable limits (0.2–0.3) at moderate-to-high fishing mortality values. This study provides necessary information about the reproductive characteristics of vulnerable, non-game species and demonstrates how spawning potential ratio modeling can be used for species that receive less management focus.

Nebraska, South Dakota↗

USGS2023

Receiver mount design, transmitter depth, and wind speed affect detection probability of acoustic telemetry transmitters in a Missouri River tributary

One of the most important considerations for acoustic telemetry study designs is detection probability between the transmitter and the receiver. Variation in environmental (i.e., wind and flow) and abiotic (i.e., bathymetry) conditions among aquatic systems can lead to differences in detection probability temporally or between systems. In this study we evaluate the effect of distance, receiver mount design, transmitter depth, and wind speed on detection probabilities of two models of acoustic transmitters in a mid-sized river. InnovaSea V16-6H (hereafter V16) and V13-1L (hereafter V13) tags were deployed in the James River, SD at 0.36 m (deep) and 2.29 m (V16 tag) or 1.98 m (V13 tag; shallow) above the benthic surface downstream of InnovaSea VR2W stationary receivers at distances of 100, 200, or 300 m. We used two receiver mount designs that included a fixed position within a PVC pipe on the downstream side of a bridge piling or a metal frame deployed in the middle of the river channel. Tags were deployed for 72 h at each location, and hourly detections were summarized. We evaluated downstream distance, receiver mount design, tag depth, and wind effects on tag detection using Bayesian logistic regression.

South Dakota↗