Migration patterns of Atlantic halibut captured in the southern Gulf of St. Lawrence as assessed with pop-up satellite archival and Floy tags

This study provides evidence of two subpopulations of Atlantic halibut (Hippoglossus hippoglossus) in the southern Gulf of St. Lawrence. The migrations of 20 Atlantic halibut captured in the coastal waters of Prince Edward Island, Canada, were evaluated using pop-up satellite archival tags (PSAT). Geolocation data showed that Atlantic halibut migrated north to the Laurentian Channel via distinct eastern or western routes. Floy tagging and recapture (recapture of 18.4%) showed that less than 7.0% of Atlantic halibut exhibited dispersive behaviour outside of their annual migratory route. Overwintering occurred on the slope and in the deepest waters of the Laurentian Channel. Atlantic halibut in the deepest waters of the Laurentian Channel exhibited rapid, ∼100 m rises, presumed to be associated with spawning from January to March. The eastern and western migratory cohorts exhibited this behaviour ∼350 km apart, suggesting reproductive isolation as the basis of subpopulations. The results of this study indicate a need to reconsider the management of Gulf of St. Lawrence Atlantic halibut as one continuous population.