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Factors influencing growth in the Grand Canyon Colorado River population of flannelmouth sucker (Catostomus latippinis)

Hansen, Lindsay Erika (2021) Factors influencing growth in the Grand Canyon Colorado River population of flannelmouth sucker (Catostomus latippinis). Masters thesis, Northern Arizona University.

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The flannelmouth sucker (Catostomus latipinnis) (hereafter FMS) is currently the most abundant native fish in the Grand Canyon reaches of the Colorado River. Because it has a more stable population than other native fish in this river system, limited research has been conducted to assess its population stability, abundance, and growth. In this research, I have determined the environmental variables that affect flannelmouth sucker growth. I assessed the effects of monthly temperature, turbidity, and gross primary productivity stratified by reach in a Bayesian growth-in-length model, and use an inclusion approach operationalized by slab and spike priors for variable selection. Over a six year time series I found that gross primary productivity and temperature have positive impacts on FMS mean monthly growth rates, while higher turbidity causes a decrease in FMS monthly growth. This study shows one of the first connections between freshwater fish growth and gross primary productivity. These variables did not interact with initial fish length to influence growth rate. FMS growth rate in Grand Canyon also varied by time and location, because the environmental variables considered in this research vary across time and location. Growth is highest in reaches farther downstream from Glen Canyon Dam than in reaches nearest to the dam. Across all reaches, FMS have a higher mean monthly growth rate during summer months than winter months, and the yearly growth rate has increased between 2012 and 2018. This research is a step toward developing a better understanding of the drivers of population recovery of FMS in Grand Canyon, creating management plans that promote conservation of FMS and similar species, and predicting how the population of FMS will change in future conditions.

Item Type: Thesis (Masters)
Publisher’s Statement: © Copyright is held by the author. Digital access to this material is made possible by the Cline Library, Northern Arizona University. Further transmission, reproduction or presentation of protected items is prohibited except with permission of the author.
Keywords: Bayesian modelling; Flannelmouth sucker; freshwater fish; Grand Canyon; growth; Colorado River; Habitat
Subjects: Q Science > QL Zoology
NAU Depositing Author Academic Status: Student
Department/Unit: Graduate College > Theses and Dissertations
College of the Environment, Forestry, and Natural Sciences > School of Earth Sciences and Environmental Sustainability
Date Deposited: 09 Feb 2022 17:16
Last Modified: 09 Feb 2022 17:16
URI: https://openknowledge.nau.edu/id/eprint/5675

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