Document Type
Poster
Journal/Book Title/Conference
Utah Annual American Fisheries Society
Publisher
Utah State University
Publication Date
2-10-2025
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Abstract
Introduced species are one of the leading causes of native fish population declines globally, and predation by introduced species can impact native fish abundance, growth, and survival. In Utah Lake, many nonnative predators have been intentionally introduced over the past century to promote recreational fishing, including White Bass (Morone chrysops), one of the most abundant species in the system. June Suckers (Chasmistes liorus) are endemic to Utah Lake, but have experienced severe declines in abundance due to a combination of historical overexploitation, habitat degradation, and the introduction of nonnative fishes. Previous studies have indicated that first-year survivorship of June Suckers less than 100 mm is effectively zero, but survivorship increases to 50% by 300mm, suggesting the presence of high predation mortality for smaller individuals. Here, we examine the relative vulnerability of juvenile June Suckers to White Bass predation to determine if White Bass could be contributing to the high mortality of June Suckers at sizes less than 300mm. We used White Bass diet data collected via gastric lavage and dissection from 1983 to 2021 to fit quantile regressions of predator length to fish prey length. From these regressions, we determined the distributions of prey fish lengths in diets of White Bass of a given length, across all observed White Bass lengths. We used a catch-curve to estimate White bass relative abundance across all lengths observed, using commercial seine data from 2020 and accounting for gear size-selectivity. We then simulated the length and number of fish prey consumed by all White Bass using the abundance of White Bass at each length and the quantile regressions of prey length to predator length. We found the distribution of the length of prey items consumed to be unimodal and right-skewed with a median prey length of 39.306 mm (95% simulation confidence interval: 14.017 mm – 91.842 mm). The upper limit of the distribution of White Bass simulated prey item lengths was less than the length of June Suckers at first annulus (111 mm), suggesting that White bass predation on June Suckers would be limited to their first year. Given the high densities of White Bass in Utah Lake, predation on larval June Suckers may present a significant barrier to survival past the first annulus and could impede the establishment of a robust naturally reproducing June Sucker population in Utah Lake. Further research is needed to understand the possible impacts of other nonnative predators, such as Walleye (Sander vitreus) and Channel Catfish (Ictalurus punctatus). Our results establish a valuable predator-prey model that management agencies and stakeholders can use to inform effective management plan(s) and potentially mitigate the impact of non-native White Bass on June Sucker recruitment in Utah Lake.
Recommended Citation
Garner, Austin; Landom, Kevin; Fadlovich, Rae; and Walsworth, Timothy E., "Relative Vulnerability of Juvenile June Sucker to White Bass Predation in Utah Lake" (2025). Watershed Sciences Student Research. Paper 57.
https://digitalcommons.usu.edu/wats_stures/57