ORCID ID

0000-0002-4671-0206

Date Awarded

Summer 2020

Document Type

Thesis

Degree Name

Master of Science (M.Sc.)

Department

Virginia Institute of Marine Science

Advisor

Jan R McDowell

Committee Member

Robert A Fisher

Committee Member

Mary C Fabrizio

Committee Member

Emily B Rivest

Abstract

Channeled whelk (Busycotypus canaliculatus Linnaeus, 1758) are predatory marine gastropods that are found in intertidal regions of the continental slope along the U.S. Atlantic coast from Cape Cod, Massachusetts to Cape Canaveral, Florida. The channeled whelk is a commercially important species that supports a fishery along the Atlantic coast of the United States. The resource is managed at the state level with minimum landing size (MLS) varying by state. Biological assessments of channeled whelk in the mid-Atlantic and Massachusetts have indicated that females have a low probability of being mature when they enter the fishery. The life history characteristics of channeled whelk including slow growth, late maturation, and direct development paired with unsuitable MLS make this species vulnerable to overexploitation. Currently, the population genetic structure of channeled whelk is unknown, impeding the creation of appropriate management strategies. This study aimed to delineate the population genetic structure of channeled whelk using genotyping-by-sequencing of 252 samples from 10 resource areas from Massachusetts to South Carolina, with fine-scale sampling in the mid-Atlantic region. A total of 2,570 single nucleotide polymorphisms (SNPs) were used to estimate genetic diversity and delineate population structure among resource areas. Analysis of all 10 resource areas revealed four major genetic groups: 1) North and mid-Atlantic resource areas, 2) Pamlico Sound, North Carolina, 3) Wilmington, North Carolina, and 4) Charleston, South Carolina with additional structuring within the north and mid-Atlantic. Analysis North and mid-Atlantic resource samples indicated that Virginia Beach, Virginia was significantly different from all other mid-Atlantic resource areas (FST = 0.001 – 0.016, p < 0.001). Massachusetts and Rhode Island were also significantly different from each other (FST = 0.084, p < 0.001) and from mid-Atlantic samples (FST = 0.031 – 0.128, p < 0.001). Overall, data indicate 7 genetically distinct populations along US East Coast. Estimates of genetic divergence (FST) spanned several orders of magnitude with elevated divergence levels observed when comparing samples from across known biogeographic barriers along the Atlantic coast. FST values were highest (0.150 – 0.465, p <0.001) when comparing samples off Pamlico Sound, North Carolina, off Wilmington, North Carolina, and off Charleston, South Carolina to samples from all other resource areas. The complex population genetic structure revealed by this study underscores the need for further study and for new management strategies for the channeled whelk fishery in resource areas along the Atlantic coast. Results from this study can be used to assess alternative decisions about the appropriate scale for management of the channeled whelk resource in the mid-Atlantic region, which is threatened by overharvest and removal of whelk before they are sexually mature.

DOI

https://doi.org/10.25773/t9hf-0h81

Rights

© The Author

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