Tanner L. Carlson | Geology Reports

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↗