Migrations of Harp Seals Pagophilus groenlandicus (Erxleben) in the Northwest Atlantic

Abstract

Some 1300 harp seal pups were marked with four types of tags over 5 years from commercial sealing ships at the breeding patches off eastern Canada. Recovery rates from individual taggings ranged up to 20%. The greatest age at recovery was 4 years, 10 months. The recoveries and observational evidence show that the young seals at 4–6 weeks move out to the ice edge, drift passively with the prevailing current, and at 8–10 weeks begin to migrate northward, independently of and somewhat later than the herds of older animals. Tag recoveries in summer come from West Greenland and eastern Baffin Island. The southward migration begins in late September at high latitudes and reaches the Strait of Belle Isle by late December. Many immatures remain in arctic waters much later than the main herds, but the majority have moved south to join them in the breeding areas by April, when moulting takes place. Harp seals born in the Gulf of St. Lawrence and on the ice east of Belle Isle separate to their home areas to moult as immatures, although they mix in their summer range and on the southward migration. Probably, breeding and moulting adults remain distinct also. In the Gulf of St. Lawrence, most moulting takes place in the water, but east of Belle Isle, on ice. Moulting groups east of Belle Isle are composed at first of adult males and immatures, and are joined in the later part of April by the adult females which have given birth.