Variation in Prairie Chub hatch relationships across wet and dry years in the upper Red River basin

Abstract

ObjectiveThe Prairie Chub Macrhybopsis australis is a poorly studied minnow species endemic to the upper Red River basin and is of both state and federal conservation interest due to uncertainty about its life history and potential listing status. The upper Red River basin of Oklahoma and Texas is a harsh environment where drought and extreme flow events are exacerbated by human alterations. As an assumed pelagic‐broadcast‐spawning minnow, the Prairie Chub is capable of a protracted spawning season and larval fish survival is assumed to be linked to discharge and streamflow variability.MethodsWe systematically collected 2,017 age‐0 Prairie Chub from seven sites (North Fork Red River, Salt Fork Red River, Pease River, Red River, Prairie Dog Town Fork Red River, North Wichita River, and South Wichita River) with variable flow patterns during April–September 2019 and May–August 2020. We used otolith age estimates and back calculations to determine successful spawning dates. We used a hurdle model framework to examine relationships between hatch probability and hatch frequency.ResultHatch probability had a negative relationship with calendar day and declined as calendar day increased. Hatch counts peaked in late June and early July and declined thereafter in 2019 but showed no discernible peak during the spawning season in 2020. Hatch probability during the spawning season increased with relative flow and air temperature. Increased hatch counts were also positively related to discharge variability (CV) for the 10 d prior to hatch dates.ConclusionOur findings indicated that successful hatches had considerable spatial and temporal variability, with some sites contributing minimally to the population during some years. Spatial and temporal variability of hatch probability and hatch frequencies pose a variety of considerations for future conservation and management efforts, particularly given the pending federal listing status of the species.

Why are larger fish farther upstream? Testing multiple hypotheses using Silver Chub in two Midwestern United States riverscapes

“…We used total length data from all Silver Chub collected in the field (i.e., those retained for reproductive ecology research and those released) to fit a Bhattacharya model useful for estimating cohorts defined by modes within the length‐frequency histogram. We did not use otoliths to age fish because we were interested in using fish that were retained (otoliths available) and released (otoliths not available) for age estimates, though otoliths provide greater detail when aging (Perkin et al 2023; Wedgeworth et al 2023 [both this special section]). We used the “Bhattacharya” function from the “TropFishR” package to fit the model and develop probability density functions for each cohort detected in the data (Mildenberger et al 2017).…”

Evaluating the context dependency of large river nursery habitats for fishes in the lower Red River catchment

“…We quantified water temperature (1.0°C) because as fish grow, they become more active and more susceptible to sample gears (Goffaux et al, 2005; Guy et al, 2009). We included calendar day because abundance also changes during the first summer of life via spawning events and high early life mortality and can affect detection (Wedgeworth, 2021). Water clarity (1.0 cm) was quantified using a Secchi disk (Preisendorfer, 1986) because clearer water allows fishes to evade gears more easily (Mollenhauer et al, 2018).…”

Avoiding a macabre future for Macrhybopsis—A special section on improving management and conservation of chubs

“…Perkin et al (2023b, this special section) study longitudinal variation in size distributions of Silver Chub in the Arkansas and Ohio River basins and provide implications for management of longitudinal connectivity. Wedgeworth et al (2023, this special section) and Perkin et al (2023a, this special section) study flow–recruitment relationships for the Prairie Chub and the Shoal Chub, respectively, and separately report positive correlations between streamflow variability and hatch success in regulated rivers. Nguyen et al (2023, this special section) show that drought‐mediated changes in flow regime cause reduced occurrence of pelagic‐spawning species such as the Shoal Chub, with implications for managing populations under increasingly dry conditions in southern Great Plains rivers.…”

“…Perkin et al (2023b, this special section) study longitudinal variation in size distributions of Silver Chub in the Arkansas and Ohio River basins and provide implications for management of longitudinal connectivity. Wedgeworth et al (2023, this special section) and Perkin et al (2023a, this special section) study flow-recruitment relationships for the Prairie Chub and T A B L E 1 Conservation status of chubs in the genus Macrhybopsis according to the U.S. Endangered Species Act (ESA), the Canadian Species at Risk Act (SARA), the American Fisheries Society (AFS; from Jelks et al 2008), the International Union for the Conservation of Nature (IUCN), and NatureServe.…”