Migration pattern and evidence of homing in Atlantic wolffish (Anarhichas lupus)

Homing and site fidelity of Atlantic wolffish Anarhichas lupus was studied at the main spawning ground and four different feeding grounds in Icelandic waters. A total of 883 fish were tagged with T-bar anchor tags, whereof 349 fish also received an internally implanted data storage tag (DST). The DSTs data revealed consistent year-to-year migrations between spawning grounds and feeding grounds. Arrival time at the main spawning ground was similar for males and females, but males departed two months later, suggesting that peak of hatching of larvae was in late February. Homing was estimated to be 93% for the main spawning ground and 87% for feeding grounds. Fish tagged at the main spawning ground did not exclusively migrate to one feeding ground during the feeding season, and fish tagged at each feeding ground migrated to more than one potential spawning ground. Fish tagged at the southeast feeding ground appear to be isolated from the other areas investigated. Atlantic wolffish in Icelandic waters is currently managed as one single stock, hence the single stock management approach might need to be reconsidered.