Migration route familiarity and homing of transplanted Atlantic cod (Gadus morhua)

To investigate migration route familiarity and homing success of Atlantic cod (Gadus morhua L.), acoustically tagged spawning cod caught at the Bar Haven spawning ground, Placentia Bay, Newfoundland, were transplanted 21 km along their migratory pathway and 21 km in the opposing direction. A control group was released where caught. Transplanted groups included fish of both sexes and two size classes (58-60 cm and >70 cm). Tagged cod were then relocated using biotelemetry. All 16 control fishes were relocated at Bar Haven. Twelve of 32 transplanted fishes had known fates (seven returned to Bar Haven, the earliest 12 days after release, and five died). Significantly more cod returned from the migratory pathway (adjusted rate of 51%) compared to cod released outside of this area (13%). Small males showed the highest same year homing rates (88%): large females the poorest (0%). After one year at large, significantly more cod released in the migratory pathway returned to Bar Haven during the spawning season, suggesting that cod may repeat the migratory behaviour of previous years.