Date of Award:

8-2026

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Watershed Sciences

Committee Chair(s)

Chad N. Teal

Committee

Chad N. Teal

Committee

Timothy Walsworth

Committee

Matthew Zeigler

Abstract

Aquatic invasive species are one of the leading causes of native fish declines in the Southwestern United States. Channel Catfish Ictalurus punctatus were introduced into the Colorado River Basin, including the San Juan River, New Mexico, Colorado, and Utah for fishery enhancement during the 20th century. This introduction has contributed to the decline of native species and despite intensive mechanical removal efforts, the Channel Catfish population has persisted in the San Juan River. The Trojan Sex Chromosome approach is a promising eradication strategy that proposes the production and release of Trojan sex chromosome carriers (YY) to skew a targeted population’s sex ratio toward males, leading to population collapse. Before YY individuals could be produced and released into the San Juan River, regulatory approval (FDA) and a scalable YY production protocol are required. The goal of this project was to enhance the understanding of YY Channel Catfish production methods by evaluating the effects of exogenous hormone and heat treatments to feminize Channel Catfish along with developing Channel Catfish sex identification markers capable of discriminating among XX, XY, and YY genotypes. To accomplish these objectives, we first conducted a literature review to synthesize current information on Channel Catfish reproductive biology and tools for sex ratio manipulation. Secondly, we conducted a systematic investigation of hormone treatments (17β-estradiol and 17α-methyltestosterone) and heat treatments (36°C water temperatures) administered to Channel Catfish fry during early development (12-60 days post-fertilization). We assessed several health metrics across treatment groups, including survival, growth, feminization, and growth defects. We then developed genetic sex identification markers and tested the markers on genomic DNA samples from the San Juan River, displaying 98.9% concordance with sex. The results collected in this project can support regulatory approval for YY Channel Catfish production and the future implementation of the Trojan Sex Chromosome approach on the San Juan River.

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