Advancing Conservation Strategies for Native Eastern Highlands-Strain Walleye Sander vitreus in West Virginia: Insights from Genomic Investigations and Broodstock Screening

Abstract

Walleye, Sander vitreus, has several distinct genetic lineages throughout North America as a consequence of Pleistocene glaciation. Stocking walleye across genetic boundaries in the mid-20th century has led to the introduction of non-native strains that persist to this day. In West Virginia, the identification of the native Eastern Highlands strain led the West Virginia Division of Natural Resources (WVDNR) to employ broodstock screening to assist in the conservation of the native strain. To develop a baseline native ancestry prevalence in walleye populations throughout the state, 1532 broodstock were sampled across 17 sampling locations over a 6-year period. To evaluate the effectiveness of the current broodstock two-SNP qPCR assay protocol and identify whether more SNPs need to be implemented, 284 walleye were sequenced and ancestry-genotyped across 42 fixed SNPs between the two strains. When comparing the current protocol to the older microsatellite protocol, advancement in the ability to identify native-strain individuals was observed. Genotyping previously assigned walleye broodstock across multiple fixed SNPs revealed that the current ancestry assignment protocol, on average, assigned individuals that display 96% Eastern Highlands native ancestry to the native strain and accurately identified >93% of all pure Eastern Highlands walleye. Throughout the state of West Virginia, the New and Kanawha River systems contained a high prevalence of native ancestry, with the Ohio River and sampled impoundments displaying varying levels of ancestry. SNPs with >98% prevalence in individuals assigned to the Eastern Highlands strain were identified during the course of the study and can be implemented in future screening protocols. Our results highlight the utility of genomic approaches as tools to assist fisheries management goals and their capability to accurately identify native ancestry to assist in conservation efforts.