Movements of Atlantic halibut in the Gulf of Maine based on geolocation

Atlantic halibut are a “Species of Concern” in US waters and little is known about their movements and stock structure. Recent stock assessments drew attention to the paucity of information for assessing and managing this stock. To investigate movement patterns and stock structure, halibut were tagged off Massachusetts and Maine within US waters of the Gulf of Maine region using pop-up satellite archival tags and data storage tags. A hidden Markov model (HMM) geolocation method previously developed for other groundfish species was adapted to estimate the movement tracks of the tagged halibut (n = 25) based on the tag-recorded depth and temperature. Total distance travelled based on geolocation ranged from 36 to 1701 km, whereas straight line distance between tagging and end locations ranged from 0.4 to 440.7 km. Estimated movement rates varied between 2.7 and 10 km day−1. Two tagged halibut made long-distance movements to putative spawning habitat in the Northeast Channel off Georges Bank. Thirteen (13) out of 25 geolocated individuals were estimated to have reached Canadian waters. Geolocation results revealed home range, return movement, and seasonal migration movement patterns exhibited by the tagged halibut. The HMM geolocation method could be a useful tool in providing information on halibut movements that can inform stock assessment and management decisions.