Sibship Analysis of Fall and Spring Spawn Gulf Sturgeon Eggs in the Choctawhatchee River, Florida

Author

Lyric McCullouch

Date of Award

5-2025

Degree Type

Honors College Thesis

Academic Program

Biological Sciences BS

Department

Biological Sciences

First Advisor

Brian Kreiser, Ph.D.

Advisor Department

Biological Sciences

Abstract

The Gulf sturgeon (Acipenser oxyrinchus desotoi) is an anadromous species that inhabits rivers along the northern Gulf of Mexico. Facing challenges from overfishing and habitat alteration, the Gulf sturgeon is listed as threatened under the Endangered Species Act. This study investigated the genetic distinctiveness of fall and spring spawning groups of Gulf sturgeon in the Choctawhatchee River, a critical habitat for the species. In this study, I used microsatellite loci to analyze Gulf sturgeon eggs previously collected in the fall and spring of 2019 and 2020. The goals of this study were to verify the genetic identity of eggs sampled in the fall and spring as belonging to appropriate spawning groups and to estimate the effective number of breeders (N_b) for each spawning season. STRUCTURE analysis was used to determine the presence of two genetic clusters. Genetic diversity metrics such as observed heterozygosity (H_O), expected heterozygosity (H_E), and allelic richness (A_R) were calculated to assess genetic health. Additionally, the effective number of breeders (N_b) was estimated using COLONY. The results confirmed the existence of two genetically distinct spawning groups corresponding to the fall and spring seasons. High average membership coefficients (q) supported this genetic distinction. Genetic diversity metrics were similar across all four cohorts. Four full-sibling pairs were identified across three cohorts, all originating from the same sampling pads. Estimates of N_b were generally similar across cohorts and had overlapping confidence intervals, suggesting relatively similar numbers of reproductive adults in both fall and spring.

Copyright

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Recommended Citation

McCullouch, Lyric, "Sibship Analysis of Fall and Spring Spawn Gulf Sturgeon Eggs in the Choctawhatchee River, Florida" (2025). Honors Theses. 1022.
https://aquila.usm.edu/honors_theses/1022