IPHC Seminar Series 22-01 High-quality genomics toward improving fishery management of Greenland Halibut in the North Atlantic. Anne-Laure Ferchaud, Normandeau E, Babin C, Audet C, Morgan J, Treble M, Walkusz W, Lambert Y & Bernatchez L. - Département de Biologie, Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, QuébecAbstract - The Greenland Halibut is one of the main demersal fish species commercially exploited in Eastern Canada, and accurate information on geographic population structure and local adaptation are thus required to contribute to maintain the long-term sustainability of this species. We de novo assembled the reference genome by combining long read sequencing technology with scaffolding, containing more than 95% of gene completeness and identified the 2 sex chromosomes and subsequently demonstrated the importance of considering sex-linked markers in such studies. We then generated high-quality whole-genome libraries from 1297 Greenland Halibut sampled from 32 localities across the Northwest Atlantic (from Arctic Canadian and Greenlandic coasts to the Gulf of St Lawrence). Our analysis resolution allowed identifying population genetic structure throughout the species range and notably revealing the high connectivity between Canadian and Greenland coasts and the specificity of Gulf of St Lawrence. We identified genomic regions associated with environmental variables and implied in high differentiation between the Gulf of St Lawrence and the rest of the Atlantic. Altogether, our results revealed a pattern of spatial selection in a marine fish species with high dispersal potential, and will help supporting the management of this important exploited species.