Abstract

The greater amberjack (GAJ), Seriola dumerili is a popular recreational fish also exploited commercially in waters of the Gulf of Mexico and South Atlantic regions of the US. Current information on population genetic structure of greater amberjack is limited to two studies based on mitochondrial DNA variation and microsatellite markers, respectively. Some weak support for divergence between Atlantic and Gulf of Mexico stocks was revealed by both studies but the delineation of these two stocks and patterns of mixing between them are not clearly understood due to limitations of the sampling designs of the two initial studies. This study will address these limitations by applying genome scans generated by the double digest RAD (dd-RAD) sequencing protocol and a comprehensive sampling from the Carolinas to the Western Gulf of Mexico to describe stock structure of the species in the region. Samples were collected between 2021 and 2023 during tagging and fishery-dependent and independent sampling surveys along the US East coast (North Carolina and Southeast Florida) and the Southeastern, Northeastern, Southwestern, and Northwestern Gulf of Mexico. Sampling was repeated over two years to allow testing the temporal stability of inferred patterns. Genomic resources needed to interpret genome scans are being developed in a first project component by sequencing the genome of one GAJ specimen using PACBIO Hifi and Illumina Novaseq sequencing. Initial assembly efforts yielded a 660Mb reference in 414 contigs with an N50 over 10 Mb. Geographic samples will be assayed using the dd-RAD sequencing protocol and analyzed using the reference genome. Current status of the project and initial results will be presented.