Variation in abundance and hatch date of Prairie Chub Machrybopsis australis in the upper Red River basin

Understanding multi-scale population and life history relationships is key to informing management decisions. Abundance and life history relationships can provide insight on a species' status, population dynamics, recruitment requirements and guide fine scale conservation efforts. Life history strategies are often associated with a specialized habitat, connectivity and predictable flow patterns. These associations may vary across space and time. The Prairie Chub Machrybopsis australis is endemic to the upper Red River basin of Oklahoma and Texas. The Prairie Chub is of conservation interest due to uncertainty about its life history and status. Prairie Chub distributions are related to coarse scale flow metrics and are truncated by fragmentation. The goal of my thesis was to examine fine scale relationships to Prairie chub life history and abundance. For my first objective, I modeled the relationship between Prairie Chub hatch success and environmental variation. For my second objective, I estimated abundance and modelled the relationship between adult and juvenile Prairie Chub abundance and environmental variation. My findings help build upon known occurrence relationships and provide management agencies with a more complete picture of factors and potential threats influencing Prairie Chub populations and persistence

Paradigm versus paradox on the prairie: testing competing stream fish movement frameworks using an imperiled Great Plains minnow

Background: Movement information can improve conservation of imperiled species, yet movement is not quantified for many organisms in need of conservation. Prairie chub (Macrhybopsis australis) is a regionally endemic freshwater fish with unquantified movement ecology and currently considered for listing under the Endangered Species Act. The purpose of this study was to test competing ecological theories for prairie chub movement, including the colonization cycle hypothesis (CCH) that posits adults must make upstream movements to compensate for downstream drift at early life stages, and the restricted movement paradigm (RMP) that describes populations as heterogeneous mixes of mostly stationary and few mobile fish. Methods: We tagged prairie chub with visible implant elastomer during the summer (May–August) of 2019 and 2020 to estimate net distance moved (m) and movement rate (m/d). We tested the hypotheses that observed prairie chub movement would be greater than expected under the RMP and that prairie chub movement would be biased in an upstream direction as predicted by the CCH. Results: We tagged 5771 prairie chub and recaptured 213 individuals across 2019 and 2020. The stationary and mobile components of the prairie chub population moved an order of magnitude further and faster than expected under the RMP during both years. However, we found only limited evidence of upstream bias in adult prairie chub movement as would be expected under the CCH. Conclusions: Our findings are partly inconsistent with the RMP and the CCH, and instead closely follow the drift paradox (DP), in which upstream populations persist despite presumed downstream drift during early life stages and in the apparent absence of upstream bias in recolonization. Previous mathematical solutions to the DP suggest organisms that experience drift maintain upstream populations through either minimization of drift periods such that small amounts of upstream movement are needed to counter the effects of advection or increasing dispersal regardless of directionality. We conclude that the resolution to the DP for prairie chub is an increase in total dispersal and our results provide insight into the spatial scales at which prairie chub conservation and management may need to operate to maintain broad-scale habitat connectivity

A Hierarchical Approach to Fish Conservation in Semiarid Landscapes: A Need to Understand Multiscale Environmental Relationships

A multiscale perspective is essential for conservation planning of riverine fishes. Coarse-scale habitat (e.g., basis) can influence both finer-scale habitat characteristics (e.g., reaches and microhabitat) and associated species distributions. Finer-scale management and habitat rehabilitation efforts can fail without the consideration of coarser-scale constraints. We provide a conceptual hierarchical framework for multiscale fish conservation strategies in the semiarid Great Plains. The Great Plains stream network is highly fragmented due to dam construction, water withdrawals, and increased drought severity. Our framework uses relationships with basin-scale connectivity and streamflow and reach-scale physicochemical characteristics in the context of aiding species reintroduction and stream habitat improvements