Date of Award

12-2025

Document Type

Thesis

Degree Name

Master of Science (MS)

Degree Statement

Master of Science in Fisheries

Department

Department of Fisheries

Committee Chair

Glass, Jessica

Committee Chair

López, Andrés

Committee Member

Dressel, Sherri

Table of Contents

Chapter 1: Introduction

Chapter 2: Genetic diversity and population structure of Pacific Herring (Clupea pallasii) in the eastern Bering Sea

Chapter 3: Genetic basis for sex determination in Pacific Herring (Clupea pallasii)

Chapter 4: General conclusions.

Abstract

Pacific herring (Clupea pallasii) is a critical forage fish to the marine environment, economy, and culture of Alaska. However, despite the importance of Pacific herring in Alaska and throughout the North Pacific, knowledge gaps exist for foundational genomic characteristics of the species, including genetic population structure and the basis of genetic sex determination. In this thesis, I addressed these knowledge gaps using low coverage, whole genome sequencing. I assessed population structure and genetic diversity across seven sampling sites and found three genetic populations: Unalaska, the farthest south sampling location, Kotzebue, the farthest north, and a third group unassociated with geographic location comprised of the remaining five sites. Within this mixed group, genetic signal was most strongly localized to chromosome 12, potentially indicating a chromosomal inversion. This evidence of genetic structuring supports the current spatial management of Pacific herring fisheries in the eastern Bering Sea, although further research should resolve the potential of structural variants. I also examined the basis of genetic sex determination in Pacific herring using samples from two highly diverged populations of herring: the Bering Sea and the Gulf of Alaska. I found a peak of high Fst values on chromosome 8 in the same genomic region of genetic sex determination in Atlantic herring, the sister species to Pacific herring. These results show that this sex determining region has been preserved in Pacific herring since its divergence from Atlantic herring, and between two highly diverged populations of Pacific herring in Alaska. This data will help add sex-specific aspects to studies of herring population dynamics, reproductive behavior, and the ecologic roles of each sex. Together, both research projects provide essential genetic information for Pacific herring that will inform future research and guide region-specific management strategies that will contribute to the long-term resilience of this critical forage fish.

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