Diverse migratory behaviors of Atlantic halibut (Hippoglossus hippoglossus, L.) based on the 2000–2017 Maine halibut tagging program

Accurately delineating the spatial extent of fish stocks and the degree to which stocks mix is important for understanding the effects of fisheries management and environmental change.This paper describes migratory behaviors of Atlantic halibut (Hippoglossus hippoglossus L.) tagged with conventional wire tags in the U.S. portion of the Gulf of Maine between 2000 and 2017.There were 412 recaptures reported out of 2 573 releases, a return rate of 16.0%.These returns illustrate that although most fish are recaptured close to the release point with a median distance at recapture of 38 km, Gulf of Maine Atlantic halibut also engage in dispersive behavior with some fish travelling at least 1 564 km.Returns from Canadian waters accounted for 43.2% of total recaptures.A generalized linear model found greater distances at recapture related to greater days at liberty and during winter.Fish size explained a negligible proportion (<1%) of the variability in recapture distance.Most (76%) recaptures were from waters of the Gulf of Maine and the Western Scotian Shelf off Canada, suggesting a higher level of mixing within this transnational boundary area than to elsewhere.This contrasts common assumptions about stock structure made for assessment and management purposes.